Search

We set out to evaluate multiplex ligation dependent probe amplification (MLPA) as a tool for diagnosis and carrier detection in families with a dystrophinopathy. Fifty three Indian families with provisional diagnosis of Duchene muscular dystrophy or Becker muscular dystrophy were evaluated by MLPA and multiplex polymerase chain reaction (PCR). Sanger sequencing was used to analyze the entire gene in one patient. Mothers were tested for carrier status whenever possible. Molecular analysis of DMD gene by combining MLPA and multiplex PCR yielded a mutation detection rate of 62% (33/53). Deletions were detected in 27/53 (51%) cases, duplications in 5/53 (9%) cases, a small deletion one case and Sanger sequencing detected a nonsense mutation in one case. Mutation was not detected in 36% (19/53) cases. Fifty six percent of mothers (9/16) were found to be carriers. MLPA helped to refine the results of multiplex PCR testing in 22 patients (5 duplications, 16 deletions and one small deletion). We also describe a situation where a deletion of single exon on MLPA (but not detected by multiplex PCR) was actually due to a deletion of two nucleotides in the probe ligation site. MLPA appears to score over multiplex PCR in diagnosis and carrier detection, specifically by detecting deletions and duplications that are not detected by traditional multiplex PCR.

Steel syndrome is a rare disorder of the skeleton characterized by facial dysmorphism, short stature, carpal coalition, dislocated radial heads, bilateral hip dislocation and vertical talus. Homozygous variants in COL27A1 were reported in an extending family from Puerto Rico. Here, we report a 5-year-old girl from a non-consanguineous family with facial dysmorphism, short stature, carpal coalition, dislocation of radial heads, bilateral hip dislocation, scoliosis and vertical talus. Exome sequencing identified 2 novel compound heterozygous variants c.521_528del (p.(Cys174Serfs*34)) and c.2119CT (p.(Arg707*)) in COL27A1 in this child and the parents were heterozygous carriers. We hence report the second molecularly proven case of Steel syndrome and the first case to be reported among non-Puerto Rican population. Our report further validates the role of COL27A1 mutations in causation of Steel syndrome.

Mucopolysaccharidoses (MPS), a subgroup of lysosomal storage disorders, are caused due to deficiency of specific lysosomal enzyme involved in catabolism of glycosaminoglycans. To date more than 200 pathogenic variants in the alpha-l-iduronidase (IDUA) for MPS I and ∼500 pathogenic variants in the iduronate-2-sulphatase (IDS) for MPS II have been reported worldwide. The mutation spectrum of MPS type I and MPS type II disorders in Indian population is not characterized yet. In this study, we carried out clinical, biochemical, molecular and in silico analyses to establish the mutation spectrum of MPS I and MPS II in the Indian population. We conducted molecular analysis for 60 MPS-affected patients [MPS I (n = 30) (Hurler syndrome = 17, Hurler-Scheie syndrome = 13), and MPS II (n = 30) (severe = 18, attenuated = 12)] and identified a total of 44 [MPS I (n = 22) and MPS II (n = 22)] different pathogenic variants comprising missense, nonsense, frameshift, gross deletions and splice site variants. A total of 20 [MPS I (n = 14), and MPS II (n = 6)] novel pathogenic sequence variants were identified in our patient cohort. We found that 32% of pathogenic variants detected in IDUA were recurrent and 25% in MPS II. This is the first study revealing the mutation spectrum of MPS I and MPS II patients in the Indian population.

Intraflagellar transport (IFT) is vital for the functioning of primary cilia. Defects in several components of IFT complexes cause a spectrum of ciliopathies with variable involvement of skeleton, brain, eyes, ectoderm and kidneys. We examined a child from a consanguineous family who had short stature, narrow thorax, short hands and feet, postaxial polydactyly of hands, pigmentary retinopathy, small teeth and skeletal dysplasia. The clinical phenotype of the child shows significant overlap with cranioectodermal dysplasia type I (Sensenbrenner syndrome). Whole-exome sequencing revealed a homozygous nonsense variant p.R142* in IFT52 encoding an IFT-B core complex protein as the probable cause of her condition. This is the first report of a human disease associated with IFT52.

Laurin-Sandrow syndrome (LSS) is a rare autosomal dominant disorder characterized by polysyndactyly of hands and/or feet, mirror image duplication of the feet, nasal defects, and loss of identity between fibula and tibia. The genetic basis of LSS is currently unknown. LSS shows phenotypic overlap with Haas-type polysyndactyly (HTS) regarding the digital phenotype. Here we report on five unrelated families with overlapping microduplications encompassing the Sonic hedgehog (SHH) limb enhancer ZPA regulatory sequence (ZRS) on chromosome 7q36. Clinically, the patients show polysyndactyly phenotypes and various types of lower limb malformations ranging from syndactyly to mirror image polydactyly with duplications of the fibulae. We show that larger duplications of the ZRS region (80 kb) are associated with HTS, whereas smaller duplications (80 kb) result in the LSS phenotype. On the basis of our data, the latter can be clearly distinguished from HTS by the presence of mirror image polysyndactyly of the feet with duplication of the fibula. Our results expand the clinical phenotype of the ZRS-associated syndromes and suggest that smaller duplications (80 kb) are associated with a more severe phenotype. In addition, we show that these small microduplications within the ZRS region are the underlying genetic cause of Laurin-Sandrow syndrome.

Maternal systemic lupus erythematosus and autoimmune diseases have been extremely rarely reported to cause rhizomelic chondrodysplasia punctata. We report on a fetus aborted spontaneously at 21 weeks of gestation due to complications of maternal mixed connective tissue disorder. The fetus had micrognathia, a depressed nasal bridge, flat nose, long philtrum, short columella and rhizomelia. Radiographic study showed stippling of carpal and tarsal bones, short humeri and coronal clefts in the vertebrae. Ossification centers were present at the lower end of the femora and upper end of the tibiae.

We report an unusual balanced translocation involving chromosomes 4 and 21 in a lady who had Down syndrome in her previous child. The most plausible explanation for this event is the 3:1 segregation of chromosomes at meiosis in her gametes leading to interchange trisomy 21.

Unusual facial cleft in Fryns syndrome: defect of stomodeum?: We report on a fetus with Fryns syndrome. The facial cleft was unusual. There was bilateral cleft lip with cleft palate. The intermaxillary segment was connected through the base of a mound in the midline to the lower lip. We believe this is an atypical facial cleft in Fryns syndrome and likely represents a defective stomodeum.

We studied the background information, concerns and specific queries of thirty-four families of children with Down syndrome. Majority of the parents were aware that their child has Down syndrome and has or will have mental retardation. However, most of the families were ignorant about the lack of curative treatment, chromosomal nature of the disorder and prenatal screening and testing options.

Two common mutations in the exon IIIa of fibroblast growth factor receptor 2 account for majority of the cases of Apert syndrome. They can be analyzed by amplifying the segment followed by testing for the abolition of restriction sites. We evaluated two children with typical features of Apert syndrome. A segment of FGFR2 exon IIIa was amplified by polymerase chain reaction. Restriction fragment length polymorphism was analyzed using enzymes MboI and BglI respectively for S252W and P253R mutations. The DNA segment was sequenced using ABI 310 automated DNA fragment analyzer. Both the patients showed S252W mutations. DNA sequencing confirmed the results of the restriction fragment length polymorphism. Our study is the first report from Indian subcontinent to show the prevalence of S252W mutation among Apert syndrome patients from Indian origin.

DNA damage has been found to play an important role in atherosclerosis and coronary artery disease. Genetic polymorphisms of the genes coding for enzymes involved in the metabolism of genotoxins result in different phenotypes with respect to their ability to detoxify these agents. In the present study the contribution of the polymorphism in the glutathione S-transferase gene to the development of coronary artery disease has been investigated.One hundred and ninety seven angiographically proven patients with coronary artery disease and one hundred and ninety eight age-matched controls were genotyped for glutathione S- transferase polymorphism by polymerase chain reaction. Genotype frequencies were compared in patients and controls by Chi-square test. Binary logistic regression was used to examine the relationship between genotype and disease, incorporating other variables into the model.GSTT1 null genotype was significantly decreased in patients with coronary artery disease. No significant association was found with GSTM1 genotypes. No such association was seen with smokers.Null genotype of GSTT1 is protective against coronary artery disease in our population.

Our objective was to study demographic features, clinical features, and karyotype analyses of patients with Down syndrome (DS). Our study design was a retrospective analysis, while the study was conducted in the Genetic Clinic of a tertiary-care teaching hospital.Retrospective analysis of cases referred to the Genetic Clinic was performed. Case proformas of the patients presenting with phenotypic features of DS were analyzed. The following information was recorded from the proformas: age at presentation; sex; maternal age; craniofacial and other physical features; presence and type of congenital heart disease; gastrointestinal abnormalities, and results of cytogenetic evaluation. Clinical features in neonates with DS were separately analyzed.Analysis included cases of DS presenting over a period of 7.5 years; a total of 524 patients were studied (303 males and 221 females; M:F ratio 1.37:1). Average age at presentation was 19.4 months (range: 1 day-26 years). Average maternal age at birth of the affected child was 26.8 years (range: 16-45 years). Craniofacial features noted in50% of the cases included mongoloid slant (83.9%), ear abnormalities (66.9%), epicanthic folds (56.9%), and flat facial profile (50.9%). A total of 76.3% cases had hypotonia. Characteristic limb and dermatoglyphic anomalies were seen in less than one half of cases. These included sandle sign (46.2%), unilateral or bilateral simian crease (33.2%), clinodactyly (36.1%), and brachydactyly (11.1%). Ophthalmologic abnormalities included hypertelorism (33.9%), nystagmus (3.2%), Brushfield spots (3.2%), squint (2.7%), and cataracts (1.9%). Congenital heart disease was clinically diagnosed in 96 cases (18.3%). The nature of the cardiac defect was ascertained by color Doppler examination and/or 2D-echocardiography in 58 cases. The most common cardiac anomalies were ventricular septal defect (25.8%), tetralogy of Fallot (15.5%), and atrial septal defect (12.1%). Gastrointestinal anomalies were noted in seven cases and included three cases with imperforate anus, two with Hirschsprung disease, and one each with duodenal atresia and Morgagni hernia. Results of cytogenetic abnormalities were available in 42.2%. Free trisomy (non-dysjunction) was present in 95%, 3.2% had translocation, and 1.8% were mosaics. In neonates, common features noted were mongoloid slant, ear abnormalities, flat facial profile, hypotonia, sandle sign, and clinodactyly+/-brachydactyly.All characteristic craniofacial and physical features of DS need not be present in every case. Major features noted in the present study were mongoloid slant, ear abnormalities, epicanthic folds, flat facies, and hypotonia. Congenital heart disease was present in 18.3% of cases, with ventricular septal defect being the most common type of defect. Non-dysjunction was the most common cause of the chromosomal anomaly.