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Early-onset forms of hereditary spastic paraplegia and inborn errors of metabolism that present with spastic diplegia are among the most common "mimics" of cerebral palsy. Early detection of these heterogenous genetic disorders can inform genetic counseling, anticipatory guidance, and improve outcomes, particularly where specific treatments exist. The diagnosis relies on clinical pattern recognition, biochemical testing, neuroimaging, and increasingly next-generation sequencing-based molecular testing. In this short review, we summarize the clinical and molecular understanding of: 1) childhood-onset and complex forms of hereditary spastic paraplegia (SPG5, SPG7, SPG11, SPG15, SPG35, SPG47, SPG48, SPG50, SPG51, SPG52) and, 2) the most common inborn errors of metabolism that present with phenotypes that resemble hereditary spastic paraplegia.

Multiple carboxylase deficiency (MCD) includes autosomal recessive holocarboxylase synthetase (HLCS) deficiency and biotinidase (BTD) deficiency, which are caused by HLCS and BTD gene mutations respectively. Neonatal screening for HLCS deficiency is based on 3-hydroxyisovaleryl carnitine in dry blood filter paper, and BTD deficiency is based on BTD activity determination. HLCS deficiency and BTD deficiency are characterized by neurocutaneous syndrome and organic aciduria, however, they are different in onset age, neurological symptoms and metabolic decompensation, which needed to be differentiated from acquired biotin deficiency or other genetic metabolic diseases. The diagnosis of the disease requires a combination of biochemical characteristics of hematuria, enzyme activity determination and genetic test. Routine biotin doses are effective for most MCD patients. This consensus is intended to benefit early screening and diagnosis of MCD.

Biotinidase deficiency (BTD) is a rare inherited metabolic disorder with predominant dermatogical and neurological manifestations, which if untreated leads to severe neurological sequelae. Early diagnosis and prompt treatment with biotin prevents further progression of neurological symptoms and resolution of cutaneous features. We report an interesting case of four and half year male child presenting with seizures, developmental delay with non resolving extensive skin lesions and alopecia, diagnosed as BTD and successfully treated.

Inherited metabolic disorders (IMDs) are a heterogeneous group of rare disorders characterized by disruption of metabolic pathways. To date, data on incidence and prevalence of IMDs are limited. Taking advantage of a functioning network within the Austrian metabolic group, our registry research aimed to update the data of the "Registry for Inherited Metabolic Disorders" started between 1985 and 1995 with retrospectively retrieved data on patients with IMDs according to the Society for the Study of Inborn Errors of Metabolism International Classification of Diseases 11 (SSIEM ICD11) catalogue. Included in this retrospective register were 2631 patients with an IMD according to the SSIEM ICD11 Classification, who were treated in Austria. Thus, a prevalence of 1.8/10 000 for 2020 and a median minimal birth prevalence of 16.9/100 000 (range 0.7/100 000-113/100 000) were calculated for the period 1921 to February 2021. We detected a male predominance (m:f = 1.2:1) and a mean age of currently alive patients of 17.6 years (range 5.16 months-100 years). Most common diagnoses were phenylketonuria (17.7%), classical galactosaemia (6.6%), and biotinidase deficiency (4.2%). The most common diagnosis categories were disorders of amino acid and peptide metabolism (819/2631; 31.1%), disorders of energy metabolism (396/2631; 15.1%), and lysosomal disorders (395/2631; 15.0%). In addition to its epidemiological relevance, the "Registry for Inherited Metabolic Disorders" is an important tool for enhancing an exchange between care providers. Moreover, by pooling expertise it prospectively improves patient treatment, similar to pediatric oncology protocols. A substantial requirement for ful filling this goal is to regularly update the registry and provide nationwide coverage with inclusion of all medical specialties.

Objectives Hypotonia, lethargy, eczema, alopecia, conjunctivitis, ataxia, hearing loss, optic atrophy, cognitive retardation, and seizures can occur in patients with biotinidase deficiency, and it is inherited as autosomal recessive. The aim of this study was to evaluate the cases followed up with the diagnosis of biotinidase deficiency in our unit, in terms of clinical, biochemical and genetic analyses. Methods A total of 112 cases followed up in our centre with the diagnosis of biotinidase deficiency between August 2018–September 2020 were included in the study. Data were collected retrospectively. Results A total of 112 cases (55.4% male, mean age: 2.2 ± 2.8 years) diagnosed with biotinidase deficiency were evaluated. Diagnoses were made by newborn screening in 90.2% of the cases, by family screening in 4.5%, and by investigating symptoms in 5.4%. The most frequently (27.5%) detected mutations were c.1330G>C (p.D444H)/c.1330G>C (p.D444H) homozygous mutation, followed by (13.0%) c.1330G>C (p.D444H)/c.470G>A (p.R157H) compound heterozygous mutation, and (13.0%) c.470G>A (p.R157H)/c.470G>A (p.R157H) homozygous mutation. Biotinidase enzyme levels were found to be higher in patients with the p.D444H homozygous mutation than patients with other mutations. Biotin treatment was started in all patients with enzyme deficiency. Conclusions Since the treatment is inexpensive and easily available, it is vital to detect this disease before symptom onset, especially findings related to the central nervous system, hearing and vision loss. In patients diagnosed with enzyme deficiency, the diagnosis should be definitively confirmed by genetic analysis.

Background: Neurometabolic disorders are inborn errors of metabolism with neurological manifestations. They are individually rare but as a group have a significant burden. They constitute 4.9% of genetic cause of moderate and severe mental retardation. Aims and objective: To explore clinical & metabolic profile of various forms of childhood Neurometabolic disorders. Methods: A hospital based retrospective study was conducted at Department of Pediatric Neurology, Bangabandhu Sheikh Mujib Medical University, and Dhaka from January 2016 to December 2020. Total 59 suspected children of Neurometabolic disorders (NMD), who admitted in hospital during the study period, were included. Among them 41 cases of NMD were diagnoses confirmed on the basis of clinical suspicion, biochemical test, and neuroimaging study and in few cases molecular genetics investigations. Results: Among 59 suspected cases, total 41 patients were diagnosed as Neurometabolic disorders. Most of the (63.2%) patients were within 0-3 years age. Male patients (70.73%) were outnumbered than female (29.26%). Male: Female ratio were 2.4:1. More than half of patients 25(60.90%) had parental consanguinity followed by Sib death 7 (17.07%), Prematurity 11 (26.82%). Common Neurometabolic disorders were aminoacidopathy 14 (34.14%) and lysosomal storage disorders 15 (36.58%) followed by mitochondrial disorders 5(12.19%), Urea cycle disorders 3(7.31%), CHO metabolism disorders 5(2.43%), Peroxisomal disorders 3(7.31%). Among aminoacidopathy, Organic acidamia 4(9.72%), MSUD 3(7.31%), PKU 2(4.86%), Gluteric Aciduria 3(7.31%), and Biotinidase deficiency disorder 1(2.43%) were common disorders. Among lysosomal storage disorders, mucopolysaccaridosis 4(9.72%) and metachromatic leukodystrophy 8(19.44%) were most common disorders. Common presentations were developmental delay 37(90.24%), developmental regression 21(51.21%), hypotonia 29(70.73) and seizures 26(63.41%). Neuroimaging changes found in about three fourth (80.49%) of cases. About 26.82% cases presented with white matter hyper intensity followed by basal ganglia hyper intensity (19.51%) and cerebral atrophy (14.63%). Abnormally high ammonia and lactate found in 6(14.63%) and 10(24.40%) cases respectively followed by Positive urinary ketones 8 (19.51%). Conclusions: Neurometabolic disorders are not uncommon. The commonest neurometabolic disorders were aminoaciduria and lysosomal storage disease in our study. Among aminoacid disorders, Organic acidamia, MSUD, Glutaric aciduria and in lysosomal storage disorders metachromatic leukodystrophy & Mucopolysaccharoidosis were common disorders. Neuroimaging changes were found in about three- forth cases in this study.

Objective To identify the biotinidase (BTD) gene mutations in patients with biotinidase deficiency in our region; and to determine the phenotype-genotype correlations in the presence of clinical findings. Study design Descriptive study. Place and duration of study Department of Medical Genetics and Pediatric Metabolism Outpatient Clinic, Faculty of Medicine, Harran University, between January 2018 and June 2020. Methodology Two hundred and nine patients, who were found positive for biotinidase deficiency in heel blood screening, were included. Genomic DNA was isolated from peripheral blood. Next-generation DNA sequencing analysis was performed using primers covering the exon regions of the BTD gene. The results were analysed by the mutation surveyor programme. Results The most common mutation was c.1330 G>C (p.D444H) and the second most common mutation was c.470 G>A (p.R157H). The majority of the mutations are missense; and they are especially located in the exon 4. The most frequent mutations were found to be D444H and R157H with a rate of 66.66% in symptomatic patients. Conclusion Common mutations in BTD deficiencies were indentified. Associating them with phenotype-genotype data will assist clinicians in better genetic counselling and management in the future by implementing prevention programmes. Key Words: Biotinidase deficiency, BTD gene, Newborn screening, Inherited metabolic disease, Newborn screening programme.

Vitamin responsive conditions can be either due to inherited defects in the metabolic pathways resulting in vitamin dependency or due to acquired deficiency states. Due to widespread malnutrition and predominantly vegetarian population in India, vitamin deficiency state is quite common and early identification is essential. Inherited defects, if treated earlier, lead to reduced morbidity and mortality and improvement in long-term neurocognitive outcomes. Various vitamin responsive conditions in pediatric neurology shall be discussed in this review. Infantile presentation of thiamine deficiency results in beriberi, and in adults, it leads to Wernicke’s encephalopathy and Korsakoff psychosis. Biotin thiamine-responsive basal ganglia disease is a defect of thiamine transporter 2, which leads to neuroregression and characteristic neuroimaging features of basal ganglia involvement, it responds to high doses of biotin and thiamine. Riboflavin is an enzyme involved in mitochondrial energy synthesis and is supplemented in various mitochondrial metabolic conditions. Brown-Vialetto-Van Laere syndrome is progressive pontobulbar palsy caused by defect in riboflavin transporters responsive to high doses of riboflavin. Pyridoxine responsive epilepsy presents with pharmacoresistant seizures in neonatal or early infantile age, biotinidase deficiency also presents with similar neurological manifestations, but typical cutaneous symptoms of rash and seborrheic dermatitis also occur. Both are epileptic encephalopathies and any infant presenting with epilepsy not responding to conventional AEDs must be given a trial of pyridoxine, biotin, and folinic acid. Vitamin B12 responsive conditions can include deficiency states, such as those manifesting with peripheral neuropathy and the syndrome of infantile tremor syndrome (developmental delay or regression, tremors, and megaloblastic anemia) as well as inherited disorders of homocysteine and cobalamin metabolism. These disorders are differentiated on the basis of clinical phenotype and laboratory parameters (serum B12, homocysteine levels, methylmalonic acid levels, etc.). Infantile tremor syndrome responds drastically to mega doses of Vitamin B12 and other multivitamins. Vitamin E deficiency causes ataxia with Vitamin E deficiency, other vitamins which can neurological symptoms include Vitamin C (pseudoparalysis) and Vitamin K (central nervous system bleeds). It is imperative for a practicing pediatrician to be well versed with these conditions, as these are potentially treatable conditions.

Biotinidase deficiency (BD) is an autosomal recessive disorder caused by bi-allelic mutation in the BTD gene. Clinical manifestations in BD mainly depends on residual biotinidase enzyme activity, although there are some exceptions. Broadly BD disorders are classified as profound BD and partial BD. Further profound BD can be early onset, late onset, and sometimes may be asymptomatic. Clinically late-onset profound BD can present with spectrum of manifestations ranging from single organ to multiple organ involvement, typically affecting function of brain, eye, ear, and skin. Here, a first-born child to consanguineous parents with late-onset profound BD presenting with hyperventilation secondary to lactic acidosis, hypotonia, evolving spasticity, and abnormal neuroimaging findings caused by novel homozygous variant, c.466-3T>G in the BTD gene is reported.

Biotinidase deficiency (BD) is an autosomal recessive inherited disorder in which the enzyme biotinidase is totally or partially defective and the vitamin biotin is not recycled. BD meets the major criteria for a population screening program. Newborn bloodspot screening (NBS) allows early diagnosis of BD, thus preventing the high morbidity and mortality associated with untreated disease. Both profound and partial BD variant can be detected by NBS test, and serum enzyme activity and/or mutational analysis are required for definitive diagnosis. In Italy, BD is included in the screening panel for inborn errors of metabolism (IEMs) that has been declared mandatory in 2016. We analyzed the data of the first 3 years of the NBS for BD in our region (Abruzzo, Italy), with the aim to describe the outcomes of this recently introduced screening program. In over 26,393 newborns screened, we found 2 carriers and 16 cases with genotype associated with partial BD. Since the serum biotinidase assay has been recently introduced in our algorithm, only three of our newborns met the criteria of genetic and biochemical confirmation, with an incidence of 1:8797, which is in the high range of what has been reported in the literature. All affected infants carried the 1330G>C (D444H) variant in compound heterozygosis, with variants known to be associated with profound BD. A variant previously not described and likely pathogenic was found in one newborn. None of the infants had signs or symptoms. The study of the distribution of the enzyme activity in our population allowed us to validate the adopted cutoff with which the program has a positive predictive value of 18% and to analyze some preanalytical factors influencing biotinidase activity: A correlation of the enzyme activity with gestational age and time at specimen collection was found. Lower mean values of enzyme activity were found in infants born in the summer.

Biotinidase deficiency (BD) is an autosomal recessively inherited disorder that was first described in 1982. Forty years after its first description, we compiled available clinical data on BD with the aim of generating a more comprehensive picture of this condition. A systematic search strategy was performed in relevant databases without limits for publication date or languages. We screened 3966 records and included 144 articles reporting individuals with BD and their clinical presentation as well as the outcomes, when available. This study included 1113 individuals with BD. More than half (51.5%) of these individuals were diagnosed by newborn screening, 43.3% in presence of clinical symptoms and 5.2% due to family screening. We grouped symptomatic individuals into four main clinical presentations: neonatal-onset (16 years; 7.7%). BD affected five main organ systems: nervous system (67.2%), skin (53.7%), eye (34.4%), auditory (26.9%) and respiratory system (17.8%). Involvement was mainly multisystemic (82.2%) of individuals, whereas isolated system presentation was seen in only 17.2% of individuals. When reported, metabolic acidosis was present in 42.4% of symptomatic individuals and characteristic abnormal organic acid metabolites were found in 57.1%. Biotin treatment led to clinical stability or improvement in 89.2% of individuals. 1.6% of reported individuals with BD died due to non-availability of treatment or late diagnosis. Newborn screening has had a major positive impact on the outcome of many individuals with BD. However, undiagnosed and non-treated BD remains a health concern. Given the risk of mortality or complications associated with late or missed diagnosis if newborn screening is not available, a trial of biotin should be considered in undiagnosed infants and adults exhibiting suspected clinical signs. Enzymatic activity and/or analysis of genetic variants can readily confirm the diagnosis of BD.

A 10-year-old girl initially diagnosed with functional visual loss was later diagnosed with progressive optic atrophy. Directed questioning at 13 years of age revealed difficulty hearing that had not been noted by the parents. Whole exome sequencing and subsequent metabolic testing confirmed biotinidase deficiency. Although biotinidase deficiency classically manifests in early childhood with multiple manifestations, such as seizures and failure to thrive, a delayed-onset form can present primarily as juvenile progressive optic atrophy. Early diagnosis is critical because biotin supplementation prevents disease and deterioration.

Neonatal Seizures, the most critical of neonatal neurologic dysfunction, has aetiology of varying prognoses. The diagnosis of underlying aetiology is most critical. With use of genetic studies, better imaging technologies, better cortical electrical activity mapping and biochemical advancement, every attempt in diagnosing a cause is made.

Endocrine disorders are more common and appear earlier in people with trisomy 21 (T21) than in the general population, with thyroid dysfunction being the most common, including both congenital and acquired hypothyroidism. The treatment for biotinidase deficiency, a condition that occurs in approximately 1 : 110,000 people, is with biotin (vitamin B7) supplementation. However, biotin can interfere with endocrine laboratory assays and cause falsely low thyroid-stimulating hormone (TSH) and elevated free thyroxine (FT4) levels. This can interfere with the timely diagnosis and subsequent treatment of congenital hypothyroidism (CH). This case report describes an infant with partial biotinidase deficiency that was confirmed on day 10 of life. Routine screening erroneously reported “normal” TSH that caused delayed diagnosis of CH due to interference with the TSH assay from concurrent biotin use. Once the biotin treatment was withheld for 4 days and the thyroid function tests repeated, an elevated TSH became apparent. Treatment with tablet levothyroxine (L-T4) was started and subsequently changed to L-T4 oral solution (Tirosint®-SOL) to overcome treatment administration difficulties encountered with the tablet form. This resulted in improved TSH control due to more accurate and consistent dosing compared with the tablet formulation. This is the first report of the use of L-T4 oral solution in an infant with T21 and biotinidase deficiency.

Objectives Biotinidase Deficiency (BD) is an autosomal recessive metabolic disorder. However, the relationship between genotype and biochemical phenotype has not been completely elucidated yet. But still, some mutations are accepted to be associated with profound or partial deficiency. We aimed to evaluate the results of biochemical enzyme activity in accordance with the presence of genetic mutations and investigate the correlation between genotype and biochemical phenotype together in the study. Methods This retrospective study was carried out using data from medical records of 133 infants detected by the newborn screening followed by serum biotinidase activity (BA) detection with semi-quantitative colorimetric method. Mutation analysis was performed to confirm the diagnosis. In addition, the expected biochemical phenotype based on the known mutant alleles were compared with the observed biochemical phenotype. Results When confirmed with mutation analysis results, the diagnostic sensitivity and specificity of serum BA with spectrophotometric method was 93.1% and 95.1%, respectively. In 93.98% of the cases conformity was observed between the biochemical phenotype and the genotype. The c.1330 G>C(p.D444H) and c.470 G>A (p.Arg157His) were the most common allelic variants with frequencies of 63.69% and 33.75%, respectively. Conclusions The diagnostic test is supposed to have a high sensitivity to identify asymptomatic BD patients. Apparently healthy cases with almost normal enzyme activity and a variant allele in the genetic analysis were reported to present symptoms under stress conditions, which should be kept in mind. This study can be accepted as an informative report as it may contribute to the literature in terms of the allelic frequency and determination of the relation between genotype and biochemical phenotype. Also, method verification including the assessment of possible effects of non-genetic factors on BA according to the certain mutation types is warranted.

Biotinidase deficiency disorder is a rare inherited metabolic disorder with typical neurological manifestations of hypotonia, developmental delay, rashes, seizures, hearing and vision impairment. We present two cases with different and unusual clinical profiles, whose neuroimaging resembled Neuromyelitis Optica Spectrum Disorder. Case 1 was initially treated with immunomodulation with steroids and intravenous immunoglobulins, with partial improvement. However reinvestigation for worsening of symptoms showed more extensive changes on spine magnetic resonance imaging. Raised lactate and alanine levels on repeat cerebrospinal fluid testing resulted in further investigations that revealed a biotinidase deficiency. Case 2 presented mainly with respiratory symptoms: a barium swallow suggested bulbar dysfunction. Neuroimaging of brain and spine was similar to that in case 1 and the child was promptly investigated for and confirmed to have biotinidase deficiency. Both cases responded to biotin supplementation. It is important to be cognisant of atypical neurological presentations of biotinidase deficiency including those that mimic immune mediated neurodemyelination disorders, as biotinidase deficiency is potentially treatable.

Biotinidase deficiency (BD) is a rare autosomal recessive metabolic disease. Previously the disease was identified only by clinical signs and symptoms, and since recently, it has been included in newborn screening programs (NBS) worldwide, though not commonly. In Europe, BD prevalence varies highly among different countries, e.g., from 1:7 116 in Turkey to 1:75 842 in Switzerland. This paper aimed to present the molecular spectrum of BD (profound and partial forms) in Polish patients diagnosed within the national NBS of 1,071,463 newborns. The initial suspicion of BD was based on an abnormal biotinidase activity result determined in a dry blood spot (DBS) by colorimetric and by fluorimetric methods while biochemical verification was determined by serum biotinidase activity (as quantitative analysis). The final diagnosis of BD was established by serum enzyme activity and the BTD gene direct sequencing. The obtained results allowed for the estimation of disease prevalence (1:66,966 births, while 1:178,577 for profound and 1:107,146 for partial forms), and gave novel data on the molecular etiology of BD.

Biyotinidaz eksikliği, nadir görülen otozomal çekinik olarak kalıtılan bir hastalıktır. Erken yenidoğan döneminde tedavi edilmezse ciddi nörolojik kusurlara, metabolik bozukluklara, komaya ve ölüme neden olabilir. Yenidoğanlarda biyotinidaz eksikliği taraması ve biyotin takviyesi ile erken tedavi, semptomların çoğunun ortaya çıkması engellenebilir. Biyotinidaz enzimi, BTD geni tarafından kodlanır. BTD geninde 165'ten fazla mutasyon tanımlanmıştır. Bu olgu bildiriminde Ulusal Yenidoğan Tarama programında tespit edilen, BTD geninde homozigot çift mutasyon saptanan nadir bir tablo sunulmuş olup yeni bir allelik varyant ve genotip bildirilmiştir. Özellikle akraba evliliklerinin sık rastlanıldığı toplumlarda; yaygın görülen mutasyonlar haricinde farklı genetik tabloların da görülebileceği akılda tutulmalıdır., Biotinidase deficiency is a rare autosomal recessive inherited metabolic disorder. If not treated in the early neonatal period, it can cause serious neurological defects, metabolic abnormalities, coma and death. Screening for biotinidase deficiency in newborns and early treatment with free biotin supplementation can prevent all symptoms from occurring. The biotinidase enzyme is encoded by the BTD gene. More than 165 mutations have been identified in the BTD gene. In this case report; a rare case with homozygous double mutation in the BTD gene is presented; and a new allelic variant and genotype is defined. Especially in societies where consanguineous marriages are common; it should be kept in mind that apart from common mutations, different genetic variants may also be seen.

Biotinidase deficiency (BTD) is hereditary autosomal recessive disorder with higher morbidity and mortality if left untreated. We report this case to increase awareness about BTD, presenting with infantile seizures, encephalopathy with high anion gap metabolic acidosis, eczema and to emphasize the importance of early diagnosis in reversal of metabolic acidosis and seizures refractory to multiple anticonvulsants with biotin replacement.

Biotinidase deficiency is an inherited metabolic disorder that can present with seizures, hypotonia, and breathing issues in the newborn period. The BTD gene makes the enzyme biotinidase that aids the body in reusing biotin, a B vitamin that is essential for breaking down fats, proteins, and carbohydrates. If left untreated, developmental delay, vision and hearing loss, ataxia, skin rashes, and alopecia may develop. Treatment involves lifelong management with biotin supplements. This case report indicates that bruxism could be a dental manifestation in patients with biotinidase deficiency owing to its psychological and psychosomatic effects.

Biotinidase deficiency (BD) may cause neurological symptoms and developmental problems. However, newborn screening of BD and early biotin treatment prevent the manifestation of the majority of symptoms. This study intended to examine the developmental and behavioral outcomes as well as maternal anxiety and depressive symptoms of preschool-aged children with BD and to compare these with the outcomes of healthy preschool-aged children. In total, 49 children with BD and 23 healthy children are included. All children were screened for developmental and behavioral problems. Moreover anxiety and depressive symptomatology of their mothers were evaluated. Despite the high percentage of developmental delay in BD group, the numbers of children screened positive for a developmental delay were statistically similar in children with BD and healthy children. Among patients with BD, children with risk of developmental delay had more unfavorable socio-demographic features compared to typically developing ones. Behavioral problem scores, maternal anxiety, and depressive symptoms scores of children with BD were not higher than the healthy children.Conclusion: Children with BD were not different from their healthy peers in terms of developmental and behavioral outcomes. Developmental problems of children with BD may be related to the unfavorable socio-demographic features, not the BD itself. What is known: • Biotinidase deficiency (BD) may result in neurological symptoms and developmental problems. • Newborn screening and early biotin supplementation prevent the manifestation of the majority of symptoms. What is new: • Preschool-aged children with BD identified by newborn screening are not different from their healthy peers in terms of developmental and behavioral outcomes. • Maternal anxiety and depressive symptoms scores of children with BD are similar to scores of healthy children.

Objectives: To determine the incidence of newborn screening (NBS) disorders and to study the key performance indicators of the program. Methods: This retrospective single-center study enrolled all infants who underwent NBS from January 2012 to December 2017 at Prince Sultan Military Medical City, Riyadh, Saudi Arabia. We screened 17 NBS disorders. Blood samples were collected 24 hours after birth. If the initial result was positive, a second sample was collected. True positive cases were immediately referred for medical management. Data were extracted from laboratory computerized and non-computerized records using case report forms. Results: During the study period, 56632 infants underwent NBS with a coverage rate of 100%. Thirty-eight cases were confirmed. The incidence of congenital hypothyroidism was 1:3775. The positive predictive value for the detection of congenital hypothyroidism was 11.8%. Propionic aciduria was the most common metabolic disorder, with an incidence of 1:14158. Very long-chain acyl CoA dehydrogenase deficiency and glutaric aciduria type 1 had an incidence of 1:18877 each. Phenylketonuria, biotinidase deficiency, maple syrup urine disease, and citrullinemia had an incidence of 1:28316 each. However, galactosemia and 3-methyl crotonyl carboxylase deficiency had the lowest incidence of 1:56632. Conclusion: The NBS coverage rate at our facility was 100%. Congenital hypothyroidism was the most frequently detected disorder with an incidence that matches worldwide figures. The incidence of other inherited disorders was consistent with regional figures.

Congenital metabolic disorders include type I glycogen storage disease. Examples of drugs/toxins which give rise to elevated lactate are methanol, ethanol, epinephrine and acetaminophen. L-lactate levels in CSF will generally mirror those in blood/plasma. However, increased lactate levels in CSF in the absence of increased blood/plasma lactate concentration have been reported in cases of bacterial meningitis, cerebral hypoxia, ischemia and in certain inborn errors of metabolism e.g. pyruvate dehydrogenase deficiency, mitochondrial myopathies and biotinidase deficiency. Patients with additional injuries or pre-existing known severe pathologic problem (such as malignancy, active infectious disease, rheumatoid disease) were excluded from the study. Fourty patients (32 males; 8 females; mean age, 43.1 (range, 20–97) years) who sustained isolated closed diaphyseal fracture of the femur or the tibia remained in the study group. All femoral fractures and tibial fractures were treated with an interlocking nail, with reamed technique. The value of plasma lactate pre operatively was 15.3. On the 1st POD, the mean value was 14.8 (p = 0.849), and on the 3rd POD it was 14.3. And on the 10th POD plasma lactate value was 15.3 in the control group almost similar to the preoperative mean value.

Background Biotinidase deficiency (BTD) is an autosomal recessive inborn error of metabolism provoking progressive biotin depletion, which causes, in turn, multiple carboxylase deficiency. Its infantile onset is characterized by intractable seizures associated with lethargy, psychomotor regression, hypotonia, feeding and respiratory problems, and cutaneous abnormalities. Case description We describe a 52-month-old female whose clinical and neuroradiological pictures were consistent with myelopathy, which is generally more frequent in older patients, as well as with symptoms of an infantile onset of biotinidase deficiency, revealed at 17 months. Results A biochemical biotinidase test revealed a profound deficiency of biotinidase detecting a 10% residual enzymatic activity, which led to the diagnosis of BTD. Gene sequencing revealed a compound heterozigous mutation (c.454A > C/c.1612C > T). Conclusion Our findings suggest that even if myelopathy is uncommonly reported in BTD, and generally occurs in older children, its presence in childhood-onset floppiness should always be considered as a possible marker for an atypical presentation of BTD. Although, until recently, BTD myelopathy was believed to be prevalent in older children, a spinal cord involvement has also been described in at least nine cases in early infancy. Thus, another early diagnosis suggests that myelopathy may be more frequent than previously thought, and it is probably underdiagnosed because spinal MRI is not always routinely performed on these children. Early recognition of BTD disease is important as it would lead to prompt treatment, preventing irreversible brain damage and increasing the chances of complete recovery.

Biotinidase is essential for the recycling of biotin, which serves as a coenzyme for four biotin-dependent carboxylases involved in fatty acid synthesis, gluconeogenesis, and amino acid catabolism.1 Biotinidase deficiency (BD) is a rare, autosomal recessively inherited disorder that if untreated can cause neurological symptoms including seizures, hypotonia, respiratory abnormalities, and vison/hearing loss, especially in countries that do not screen newborns.2 This condition is readily treatable with the administration of biotin, but delays in diagnosis and initiation of therapy can result in irreversible neurological defects. Typically, patients with BD are diagnosed as newborns and treated with biotin administration throughout childhood. Although there are several case reports of adult-onset BD, most patients show some initial symptoms by their 20s or 30s.3, 4 Here, we report an autopsy case of a patient who was 63 years old at the onset of acutely progressing leukoencephalopathy that was subsequently diagnosed as BD.

Biotinidase deficiency is an autosomal recessive inherited inborn error of biotin metabolism. Biotin as a water-soluble vitamin is the prosthetic group of biotin-dependent carboxylase enzymes, and by enhancing their function plays a key role in amino acid catabolism, fatty acid synthesis, and gluconeogenesis. Beyond its prosthetic group role, it has been recognized that biotin regulates the level of gene transcription in the eukaryotic cells, therefore any defect in these pathways causes a multisystem metabolic disorder characterized by neurological and cutaneous symptoms. We report the identification of a novel pathogenic variant in the BTD gene, c.528_542del15 (p.Asn197_Ser201del, UniProt P43251-1) in an Iranian consanguineous family with a severe form of the disease. The segregation analysis in the family was consistent with phenotype and the identified variant was predicated as a pathogenic mutation by the in-silico prediction tools. Computer structural modeling suggests the deleted amino acid residues are located near the biotinidase active site and disrupt the special conformations which are critical for the enzyme activity, and also N-glycosylation. This study further expands the mutation spectrum of the BTD gene underlying cause of profound biotinidase deficiency.

Objective: In this study, it was aimed to determine the anxiety levels of mothers associated with newborn hearing screening test and heel prick blood sampling.Methods: A randomized controlled trial of 112 mothers who applied for newborn screening in a public hospital were conducted. The mothers were divided into two groups depending on their baby's assigned group; hearing screening test group (HST group) or heel prick blood sampling group (HBS group). The study was completed with a total of 101 participants. Parental Information Form, Subjective Units of Distress Scale (SUDS), State-Trait Anxiety Inventory (STAI-S, STAI-T) were used in data collection. Data analysis were performed by using descriptive statistics, Mann-Whitney U test, Kruskal Wallis test, Independent groups t test, Pearson and Spearman correlation.Results: In the HST and HBS groups, the score median of the SUDS was 5,0 (IQR: 4,0-7,0) and 5,0 (IQR: 4,0-7,0), the score average of the STAI-S was 39,8±6,7 and 41,3±7,6, and the score average of the STAI-T was 42,5±7,1 and 41,4±6,5, respectively. There were significant relationships between the mothers' scores of the SUDS, STAI-S and STAI-T.Conclusion: The mothers' anxiety associated with hearing screening test and heel prick blood sampling were higher than Spielberger’s female population. There was no difference between the anxiety of the mothers according to whether the screening test is interventional. In order to avoid problems associated with parental anxiety, it may be advisable to investigate appropriate methods to reduce the anxiety of mothers.

Biotin is a water-soluble B-complex vitamin that functions as a cofactor of five carboxylases. Because biotin-dependent carboxylases catalyze indispensable cellular metabolic functions, biotin deficiency is considered to be involved in various pathological conditions. Moreover, biotin supplementation shows pharmacological effects in vivo. However, the precise mechanisms by which biotin deficiency induces pathological conditions remain unclear. Although abnormal metabolites are used as indicators for biotin deficiency, few comprehensive analyses of total metabolites have been reported. In this study, we analyzed the metabolomic profiles of liver extracts prepared from biotin-sufficient (BS) and -deficient (BD) mice. Thirteen of 126 metabolites showed significantly different concentrations between liver extracts from BD and BS mice. The concentrations of 5 essential amino acids, Met, Val, Thr, Ile, and Leu, and 2 conditionally essential amino acids, Cys and Tyr were significantly lower in BD mice than in BS mice. Among these, the concentrations of sulfur-containing amino acids, Cys and Met, were more than 1.5-fold lower in BD mice. The concentrations of Met metabolites, such as S-adenosylmethionine and S-adenosylhomocysteine were not significantly different between the two groups. The concentrations of glutathione and its reaction intermediates γ-Glu-Cys tendency to be lower in BD mice. The present study revealed that biotin deficiency induces an abnormal amino acids composition, especially among sulfur-containing amino acids and provide important information on the effect of biotin as a pharmacological agent.

Objective Genetic carrier screening has the potential to identify couples at risk of having a child affected with an autosomal recessive or X-linked disorder. However, the current prevalence of carrier status for these conditions in developing countries is not well defined. This study assesses the prevalence of carrier status of selected genetic conditions utilizing an expanded, pan-ethnic genetic carrier screening panel (ECS) in a large population of Mexican patients. Methods Retrospective chart review of all patients tested with a single ECS panel at an international infertility center from 2012 to 2018 were included, and the prevalence of positive carrier status in a Mexican population was evaluated. Results Eight hundred five individuals were analyzed with ECS testing for 283 genetic conditions. Three hundred fifty-two carriers (43.7%) were identified with 503 pathogenic variants in 145 different genes. Seventeen of the 391 participating couples (4.34%) were identified as being at-risk couples. The most prevalent alleles found were associated with alpha thalassemia, cystic fibrosis, GJB2 nonsyndromic hearing loss, biotinidase deficiency, and familial Mediterranean fever. Conclusion Based on the prevalence and severity of Mendelian disorders, we recommend that couples who wish to conceive regardless of their ethnicity background explore carrier screening and genetic counseling prior to reproductive medical treatment.

Objective: To determine the reference interval of biotinidase activity in healthy neonates. Method: The cross-sectional study was conducted at the Department of Chemical Pathology and Endocrinology, Armed Forces Institute of Pathology, Rawalpindi, Pakistan, from May to November 2019, and comprised blood samples collected from healthy neonates aged 2-6 days. The samples were collected on filter paper and analysed on genetic screening processor based on dissociation-enhanced lanthanide flouroimmunoassay. Data was analysed using SPSS 21. Results: Of the 120 dried blood spot specimens, 81(67.5%) were from male babies and 39(32.5%) from female babies. Reference interval for biotinidase activity, based on 2.5th and 97.5th percentiles, was from 3.0 to 11.0 nmol/ml/min. Conclusion: Screening of newborns for biotinidase deficiency is crucial to prevent irreversible neurological damage. Key Words: Biotinidase reference interval, Biotinidase deficiency, Newborn screening in Pakistan.

Purpose: to review the available literature on the relationship between hearing disorders and Biotinidase deficiency. Methods: a literature search carried out between October 2018 and August 2021, on the following databases: ELSEVIER, MEDLINE, SciELO, LILACS. Descriptors were used in English, Portuguese, and Spanish. PRISMA tools were used to select the articles and STROBE was used to analyze them. Literature Review: the selected articles were published between 1983 and 2020 and answered the guiding question of the research. Observational studies, case series studies, and case reports were included. Articles without a methodology description, or carried out by the same author and with the same sample were excluded. The initial search strategy identified 152 articles. After applying the inclusion and exclusion criteria, 14 articles were selected for this review. Conclusion: the presence of Biotin was often associated with auditory pathways origins. The literature suggested a relationship between Biotinidase deficiency and hearing disorders. RESUMO Objetivo: revisar a literatura disponível sobre a relação entre alterações auditivas e deficiência da biotinidase. Métodos: a busca foi realizada entre outubro de 2018 e agosto de 2021, nas bases de dados: ELSEVIER, MEDLINE, SciELO, LILACS. Utilizaram-se descritores em português, inglês e espanhol, além das ferramentas PRISMA para seleção dos artigos e STROBE para análise dos mesmos. Revisão da Literatura: foram selecionados artigos publicados entre 1983 e 2020 que respondiam à pergunta norteadora da pesquisa. Foram incluídos estudos observacionais, estudos de série de casos e relatos de caso, e excluídos os artigos sem descrição dos métodos utilizados, realizados pelo mesmo autor e com a mesma amostra. A estratégia de busca inicial identificou 152 artigos. Após aplicados os critérios de inclusão e exclusão, 14 artigos foram incluídos na presente revisão. Conclusão: a presença de biotina foi frequentemente associada à gênese das vias auditivas. Foi observada uma relação sugerida pela literatura entre deficiência da biotinidase e alterações auditivas.

Deficiency of the biotinidase (BTD) enzyme is an inborn error of biotin metabolism caused by biallelic pathogenic variants in the BTD gene. There are two forms, partial and profound BTD deficiency, which both can be successfully treated with pharmacological doses of biotin, justifying the inclusion of this disorder in the newborn screening in numerous countries. We investigated the BTD deficiency cohort (N = 87) in our metabolic center, as it was detected upon newborn screening since 2005, and aimed to better understand the long-term course of BTD enzyme activity and how it may relate to the patients' genetic background. We observed that individuals with partial BTD deficiency display an elevation of BTD enzyme activity with increasing age in 48% of cases-a recovery which allowed adjustment or stop of biotin supplementation in 20% of all individuals. In addition, we were able to recruit 56 patients (64%) for genetic testing, revealing 19 different variants (2 novel), and constituting 22 different genotypes. Genotype-phenotype correlations revealed that the most abundant allele in our cohort p.(Asp444His) was also the most common variant in patients displaying recovery of BTD enzyme activity. Based on our results, we recommend to retest all patients with partial BTD deficiency at the age of 5 years, as this may result in an impact on therapy. Moreover, genetic testing of BTD deficient individuals can allow prediction of the severity of BTD deficiency and of the likelihood of BTD enzyme activity recovery with age.

Objective The prevalence of biotinidase deficiency and the frequency of biotinidase gene variants in Brazil are not documented. We aimed to determine the incidence of partial and profound biotinidase deficiency in the state of Minas Gerais, Brazil, and to calculate the frequency of biotinidase gene variants in the newborn screening program of Minas Gerais. Methods Neonates (1,168,385) were screened from May 2013 to June 2018. Those detected with abnormal biotinidase activity based on semi-quantitative assays underwent confirmatory serum tests. The biotinidase gene was sequenced in all confirmed cases. Results The combined incidence of partial and profound biotinidase deficiency was estimated at 1:13,909 live births (95% confidence limit 1:11,235–1:17,217), much higher than the incidence rates reported in other populations worldwide. The most frequent biotinidase gene variants were p.D444H (allele frequency, 0.016), haplotype c.1330G>C;c.511G>A (p.D444H;A171T), p.D543E, c.310-15delT (intronic), p.V199M, and p.H485Q. Together these accounted for 74.6% of the alleles analysed. Conclusion Newborn screening for biotinidase deficiency, which revealed a higher incidence in Minas Gerais, is feasible and plays a critical role in the early identification of affected neonates and prevention of symptoms and irreversible sequelae. Biotinidase gene sequencing is a useful tool to confirm the diagnosis, and also provides valuable information about genetic variability among different populations.

OBJECTIVES Biotin therapy can affect the results of many immunoassay procedures. The present study investigates biotin's interference on 25-hydroxy vitamin D (25-OHD), parathyroidhormone (PTH) and thyroid-stimulating hormone (TSH) tests using four different assay systems and biotin neutralization. DESIGN AND METHODS Enrolled in the study were 50 children diagnosed with biotinidase deficiency (BTD) undergoing treatment with biotin (5-20 mg/day) who were subjected to a series of analyses involving 25-OHD (Roche Diagnostics assays, Beckman Coulter assays, HPLC, LC/MS-MS), TSH, PTH (Roche Diagnostics assays, Beckman Coulter assays) and biotin (LC/MS-MS), before and after biotin neutralization with Streptavidin-coated magnetic particles (SMP). RESULTS The median biotin concentration was found to be 175.2 [94.0-307.1] μg/L. There was no significant difference in the 25-OHD results before and after neutralization with the Beckman Coulter, HPLC and LC-MS/MS assays. In contrast, the median 25-OHD level was seen to decrease from 90.2 [35.9-105.3] ng/mL to 29.1 [22.6-37.6] ng/mL after neutralization with the Roche assay (p

Multiple carboxylase deficiency organic Acidemia is a rare inherited metabolic disorder. It is autosomal recessive disorder of two types: Holocarboxylase deficiency and Biotinidase deficiency. It is the metabolic disorder resulting from deficiency of biotin as a co-enzyme or reduced activity of biotin-dependent carboxylases (propionyl CoA carboxylase, and 3-methylcrotonyl CoA carboxylase and pyruvate carboxylase). A case of two months' female child is reported, who presented with recurrent infantile seizures and skin rash since birth; and biochemically with metabolic acidosis, hyper-ammonemia (on and off) since birth with multiple hospitalization. She had past history of jaundice. One sibling's death at 2nd day of life due to similar complaints. Initial presentation of raised ammonia and lactate levels were the first indication to this organic academia, which was later proven by increased peak levels of various organic acids on urine organic acid analysis by gas chromatography-mass spectrometry. Key Words: Multiple carboxylase deficiency, Holocarboxylase synthetase deficiency, Biotinidase deficiency.

Insufficient dietary biotin intake, biotinidase deficiency, drug-biotin interactions can cause biotin deficiency which may result in central nervous system dysfunctions. We hypothesized that biotin deficiency could disrupt learning and memory functions by altering glutamate, glutamine, dopamine levels and protein kinase A (PKA) activity in the hippocampus. Sixteen female and 4 male Wistar rats were mated and females were separated into 4 groups. Three pups were selected from each mother and a total of 48 pups were divided into the following experimental groups. NN group, normal diet in the prenatal and postnatal period. NB group, normal diet in the prenatal and a biotin-deficient diet in the postnatal period. BN group: biotin-deficient diet in the prenatal and a normal diet in the postnatal period, BB group: biotin-deficient diet in both the prenatal and postnatal period. Open Field, Y-Maze, Object Location, and Novel Object Recognition Tests were performed in all groups and rats were sacrificed. Glutamine, glutamate, dopamine levels and PKA activity were analyzed in the hippocampi. In the open field test, distance and velocity values of NB, BN and BB groups were decreased with respect to the NN group. Learning and memory functions of NB, BN and BB groups were found to be impaired in behavioral tests. Dopamine levels and PKA activity were also decreased in all rat pups fed with a biotin deficient diet. In conclusion, we demonstrated that biotin deficiency deteriorates short-term memory and locomotor activity. This impairment may relate to decreased dopamine levels and PKA activity in the hippocampus.

Introduction: Newborn Screening (NBS) is an important public health measure in many developed countries. In developing countries like India, the benefits of NBS have been acknowledged and that screening is slowly gaining attention. Aim: To estimate the proportion for seven conditions screened in a tertiary care hospital in Southern India namely Congenital Hypothyroidism (CH), Congenital Adrenal Hyperplasia (CAH), Glucose-6-Phosphate Dehydrogenase (G6PD) deficiency, Biotinidase Deficiency (BD), Galactosemia, Phenylketonuria (PKU) and Cystic Fibrosis (CF). Materials and Methods: The present descriptive study was conducted at a tertiary care teaching hospital in Southern India during a three year period between January 2018 to December 2020. A retrospective analysis of the results of NBS by dried blood spots was done. There were 3152 live births during this period out of which 1649 babies were screened (52% coverage). Heel prick samples after 48 hour of life and prior to discharge were analysed by quantitative assessment. Neonates having positive screening results were recalled by telephonic call for confirmatory tests. Results: The CH, BD and G6PD deficiency were the most common disorders with a proportion of 1:824, 1:1649 and 1:1649, respectively. Galactosemia, CF and PKU were not found in study population. Conclusion: These results need to be corroborated with larger studies from the same geographical area.

Introduction: Biotinidase deficiency (BD) is an autosomal recessive disease causing a defect in the biotin-releasing enzyme. Newborn screening (NBS) allows early diagnosis and treatment, ensuring excellent prognosis. The aim of this study was to describe our experience in the diagnosis, treatment, and follow-up showing key strategies and unsolved questions of the management of BD patients.Methods: We analyzed data of patients identified by the Regional Centre for Newborn Screening of Verona and followed by the Inherited Metabolic Disease Unit of Verona and Neonatal Intensive Care Unit of Bolzano, Italy, from 2014 to 2020.Results: Thirty-seven patients were diagnosed by NBS (five profound and 32 partial BD), with a total incidence of 1:5,996. All were started on biotin at diagnosis and presented no symptoms at follow-up. Analysis of parents and siblings led to identification of five asymptomatic patients with partial BD: one asymptomatic parent and four young siblings. Genetic analysis of the BTD gene identified 17 different genotypes and one mutation not previously known.Discussion: Our data confirm that NBS introduction had a dramatic impact on BD diagnosis, and the incidence has increased significantly compared to other areas. Partial defects are more common than profound and have a distinctive genotype. Partial BD treatment is still controversial even at what dose of biotin and for how long. At the end, BD treatment is very easy and inexpensive and prevents severe neurological damage. Sharing experiences is essential to achieving guidelines for treatment and follow-up and a better genotype–phenotype correlation.

Purpose Despite the public health successes of newborn bloodspot screening, uncertainty associated with variant forms of primary screening targets has led to discrepancies in medical management. This study explored health-care providers’ approaches to managing atypical forms of inherited metabolic diseases (IMDs) in the absence of evidence-based guidelines. Methods Semistructured telephone interviews were conducted with metabolic specialists. 3-Methylcrotonyl CoA deficiency and variant forms of phenylketonuria, biotinidase deficiency, and fatty acid oxidation disorders were considered. Data were analyzed inductively and deductively using a novel taxonomy of uncertainty. Results Health-care providers (n = 12) navigate diagnostic, prognostic, and therapeutic challenges of uncertainty while interpreting patient and family attitudes, preferences, and ideas in the care of children with these result types. Participants explained the limits of classifying mild and atypical metabolic phenotypes. Participants also described the challenge of finding balance between cautious care and overmedicalization. Developing consistent care plans and honest communication with families were perceived as effective strategies when navigating uncertainty. Conclusion Providers’ experiences suggest a need for transparent and accessible guidelines that account for challenges associated with uncertainty generated by screening. Timely consideration of this challenge is warranted with increasing emergence of genotype-first approaches to screening.

Biotinylated antibodies/antigens are currently used in many immunoassay formats in clinical settings for diversified analytes and biomarkers to offer high detection selectivity and sensitivity. Biotin cannot be synthesized by mammals and must be taken as an essential supplement. Normal intake of biotin from various foods and milk causes no effect on the streptavidin/biotin-based immunoassays. However, overconsumption of biotin (daily doses 100–300 mg) poses a significant problem for immunoassays using the biotin-strept(avidin) pair. Biotin interferences are noted in immunoassays of thyroid markers, drugs, hormones, cancer markers, the biomarker for cardiac function (β–human chorionic gonadotropin), etc. The biotin level required for serious interference in test results varies significantly from test to test and cannot easily be predicted. Immunoassay manufacturers with technologies based on strept(avidin)-biotin binding must investigate the interference from biotin (up to at least 1200 ng/mL or 4.9 μM of biotin) in various formats. There is no concrete solution to circumvent the biotin interference encountered in blood samples, short of biotin removal. Considering the short half-life of biotin in the human body, patients must stop taking biotin supplements for >48 h before the test. However, this scenario is not considered for patients in emergency situations or those with biotinidase deficiency, mitochondrial metabolic disorders or multiple sclerosis. Apparently, a rapid analytical procedure for biotin is urgently needed to quantify for its interference in immunoassays using strep(avidin)-biotin chemistry. To date, there is no quick and reliable procedure for the detection of biotin at below nanomolar levels in blood and biological samples. Traditional lab-based techniques including HPLC/MS-MS cannot process an enormous number of public samples. Biosensors with high detection sensitivity, miniaturization, low cost, and multiplexing have the potential to address this issue.

Aim: Severe biotin deficiency associated with biotinidase enzyme deficiency in newborns is seen as severe neurological problems and hearing loss. However, the effect on the infant of deficiencies i...

Biotinidase deficiency is an autosomal recessive inherited metabolic disorder caused by mutations in the BTD gene. Clinical manifestations can be treated and effectively prevented with pharmacological doses of biotin. Nine novel mutations in BTD are reported in 14 children diagnosed by the newborn screening program in Minas Gerais, Brazil, from June 2013 to December 2017. Serum BTD enzyme activity was determined for all cases and some parents. Two of the mutations are deletions and seven missense mutations located in the exonic region of the BTD gene, mostly in exon 4. Two newborns were profoundly biotinidase-deficient (one homozygous p.A534V [c.1601C > T] and another, double heterozygous for a novel mutation p.R211S [c.631C > A] co-inherited with an already described mutation p.T532 M [c.1595C > T]). Two mutations were associated with a partial deficiency of biotinidase (p.F361 V [c.1081 T > G] in two homozygous children, and p.S311 T [c.932G > C] in a compound heterozygous child who co-inherited a known severe mutation p.Y438X [c.1314 T > A]). The remaining five mutations were found in compound heterozygous children. Hence, a definitive conclusion about the degree of biotinidase deficiency is not possible yet. These results emphasize the importance of sequencing the BTD gene as an important tool to gain a better understanding of the correlation between biochemical phenotype and genotype.

Biotin is a water-soluble vitamin that belongs to the vitamin B complex and which is an essential nutrient of all living organisms from bacteria to man. In eukaryotic cells biotin functions as a prosthetic group of enzymes, collectively known as biotin-dependent carboxylases that catalyze key reactions in gluconeogenesis, fatty acid synthesis, and amino acid catabolism. Enzyme-bound biotin acts as a vector to transfer a carboxyl group between donor and acceptor molecules during carboxylation reactions. In recent years, evidence has mounted that biotin also regulates gene expression through a mechanism beyond its role as a prosthetic group of carboxylases. These activities may offer a mechanistic background to a developing literature on the action of biotin in neurological disorders. This review summarizes the role of biotin in activating carboxylases and proposed mechanisms associated with a role in gene expression and in ameliorating neurological disease.

Background Multiple sclerosis is a disorder of the central and peripheral nervous system of young and old adults that is characterized by muscle, coordination and vision abnormalities. Multiple sclerosis is likely due to numerous causes. Methods Recently, adolescents and adults with ophthalmological and or neurological findings have been diagnosed with biotinidase deficiency. These individuals have exhibited myelopathy, paresis and/or spastic diplegia/tetraplegia with or without optic neuropathy/vision loss. These older individuals with biotinidase deficiency were considered initially to have multiple sclerosis or similar disorders before they were determined to have biotinidase deficiency. Results If a symptomatic individual with biotinidase deficiency is treated with biotin early enough, the symptoms markedly improve or completely resolve, but if treatment is delayed, the symptoms may be irreversible. Conclusion Therefore, although biotinidase deficiency is rare relative to that of multiple sclerosis, the disorder should be included in the differential diagnosis of individuals thought to have multiple sclerosis or related disorders. Biotinidase deficiency should be considered in individuals thought to have multiple sclerosis or related disorders.

Congenital biotinidase deficiency is a rare inborn error of metabolism that most commonly presents in infantile age group. Diffusion changes on magnetic resonance imaging (MRI) are sparsely described in the literature. We are presenting diffusion-weighted MRI findings in two confirmed cases of congenital biotinidase deficiency in infantile age group with review of literature.