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Alpha-ketoadipic acid is one of the metabolic intermediates of lysine and tryptophan, and it is known as the biochemical hallmark of alpha-ketoadipic aciduria (α-KA). α-KA is a rare autosomal recessive disorder. Its pathophysiology is reduced alpha-ketoadipic acid dehydrogenase activity, and that makes it difficult to metabolize lysine and tryptophan. The symptoms of this disease are multiple, e.g., psychomotor retardation, epilepsy, and ataxia, and it can even be asymptomatic. We present a case of sudden death in a 2-year-old boy with alpha-ketoadipic aciduria. Postmortem computed tomography (CT) and autopsy were performed to elucidate the cause of death. No obvious lesions could be identified except for a marked fatty liver. Urinalysis showed elevated excretion of α-ketoadipic acid.

In mucopolysaccharidoses (MPS), spinal cord compression (SCC) resulting from glycosaminoglycan (GAG) accumulation is a critical complication that can cause significant neurological and respiratory morbidities. However, clinically similar disorders such as mucolipidosis types II and III (ML) with SCC have been scarcely reported. Herein, we report four patients with ML who had SCC. Brain MRI revealed progressive spinal canal stenosis and SCC. In addition, T2-weighted high signal changes in the cervical cord were detected in two cases. Severe cases of SCC were detected as early as 1 year of age. All cases had respiratory problems. One case showed severe hypoxia and another, severe sleep apnea. In two cases, respiratory insufficiency and tetraplegia rapidly progressed as SCC progressed. Then, the patients became bedridden and needed artificial ventilation. In addition, two of the four patients died of respiratory failure. The autopsy of one patient revealed a compressed cervical cord and marked dura mater thickening due to GAG accumulation. These findings suggest that the accumulation of substrates in the dura mater caused SCC in the patients with ML. Our cases indicate that SCC is expected to be a common and critical complication of ML and MPS. MRI evaluation of cervical involvements and careful clinical observation are required in patients with ML.

Joubert syndrome (JS) is a genetic neurodevelopmental disorder characterized by lower brainstem dysplasia and cerebellar vermis agenesis termed molar tooth sign (MTS), psychomotor retardation, abnormal respiratory pattern in infancy, and oculomotor abnormalities. Arima syndrome (AS), which is a severe form of JS, is characterized by severe psychomotor retardation, congenital visual impairment, progressive renal dysfunction, and lower brainstem dysplasia from early infancy. Numerous patients with AS expire in early childhood. Recently, c.6012–12T> A in the CEP290 gene was reported as a specific variant of AS. Herein, we report the cases of two siblings showing a phenotype of JS with compound heterozygous mutations (c.6012–12T > A / c.5924delT) in the CEP290 gene. The older sister (aged 19 years) had hypotonia, hypertelorism, and anteverted nares since birth. As a neonate, she developed a transient abnormal respiratory pattern and nystagmus, and brain magnetic resonance imaging (MRI) showed MTS. The younger sister (aged 13 years) exhibited mild hypotonia and pendular nystagmus as a neonate; MRI revealed MTS. Both sisters had psychomotor retardation, oculomotor dysfunction, and bilateral renal cysts with normal renal function. They can walk and have simple conversation. They do not meet the diagnostic criteria for AS, and their symptoms were milder than those of previously reported cases with this specific mutation. This report indicates the expanding spectrum of the CEP290 variant.

Background The mitochondrial DNA MT-ATP6 gene encodes the ATP6 subunit of the mitochondrial ATP synthase. The m.9185 T > C variant in MT-ATP6 has been reported to cause various neurological disorders including late-onset Leigh syndrome (LS). To our knowledge, there has been no reported case of infantile-onset LS associated with the m.9185 T > C variant. Herein, we report a patient with early-onset LS complicated with infantile spasms who exhibited profound developmental delay. Case report A 3-month-old Japanese girl presented with focal seizures. Brain magnetic resonance imaging (MRI) revealed bilateral lesions in the basal ganglia and cerebral peduncle. Laboratory evaluation demonstrated marked elevations of lactate and pyruvate in both venous blood and cerebrospinal fluid. At 6 months, she developed infantile spasms, which were ceased by adrenocorticotropic hormone therapy. At 2 years of age, she was bedridden due to hypotonic quadriplegia and was unable to make eye contact. Whole-exome sequencing identified apparently de novo homoplasmic m.9185 T > C variant in her blood. Conclusion This is the first case report describing early infantile-onset LS associated with the m.9185 T > C variant, and thereby broadens the phenotypic spectrum of m.9185 T > C-related disorders.

A Japanese girl with polycystic kidney disease (PKD) developed normally, but at 8 months of age, she was hospitalized for acute onset dyspnea. On the day after admission to hospital, her general condition suddenly became worse. An echocardiogram showed left ventricular dilatation with thin walls, severe mitral valve regurgitation, and a reduced ejection fraction. She died of acute cardiac failure 3 hours after the sudden change. Postmortem analysis with light microscopy showed disarray of cardiomyocytes without obvious infiltration of lymphocytes, and we diagnosed her heart failure as idiopathic dilated cardiomyopathy (DCM). Clinical exome sequencing showed compound heterozygous variants in JPH2 (p.T237A/p.I414L) and a heterozygous nonsense mutation in PKD1 (p.Q4193*). To date, several variants in the JPH2 gene have been reported to be pathogenic for adult-onset hypertrophic cardiomyopathy or DCM in an autosomal dominant manner and infantile-onset DCM in an autosomal recessive manner. Additionally, autosomal dominant polycystic kidney disease is a systemic disease associated with several extrarenal manifestations, such as cardiomyopathy. Here we report a sudden infant death case of DCM and discuss the genetic variants of DCM and PKD.

Hartsfield syndrome (HS: OMIM 615465) is a rare congenital disease associated with a mutation of the fibroblast growth factor receptor 1 gene (FGFR1) with the main features of holoprosencephaly and ectrodactyly. Patients with HS also present with endocrinological deficits, such as isolated hypogonadotropic hypogonadism and central diabetes insipidus. Although there are several studies on infancy/childhood history, there is no study of infant/childhood/adolescent/young adult HS natural history and endocrinological findings. Here, we report a male patient with HS associated with a novel de novo FGFR1 mutation (c. 1868A > C). The endocrinological profile was evaluated at ages 1 and 31 years. This long-term follow-up study highlights functional changes in the posterior pituitary gland and features of bone metabolism disorder. We also describe the anterior pituitary function. To our knowledge this is the first description of the natural history of an HS patient through birth to young adult age. Although the HS infants reported in the literature develop central diabetes insipidus, little is known about the serial changes in pituitary gland function during growth in HS patients. In this study we describe an adult patient with HS who showed improvement of hypernatremia during early adulthood. In addition, we emphasize the importance of prevention and treatment of osteoporosis in HS.

Krabbe disease, one of the autosomal-recessive lysosomal storage disorders (LSDs), is caused by a deficiency of galactocerebrosidase (GALC) activity, resulting in the intracellular accumulation of psychosine, which is cytotoxic for neuronal cells. Genetically pathogenic mutations result in conformational changes in GALC and disrupt the lysosmal trafficking of cargos, which subsequently accumulate in the endoplasmic reticulum (ER). Recently, ER stress together with the activation of the unfolded protein response (UPR) has been suggested to play a key role in the pathogenesis of LSDs. In this study, we hence investigated whether the UPR is activated in Krabbe disease using COS-7 cells expressing pathogenic GALC mutants and skin fibroblasts (SFs) from Krabbe disease patients with various phenotypes, using a combination of semiquantitative and quantitative real-time polymerase chain reactions. We found that UPR activation in Krabbe disease depends on the mutations and cell types, and there is the possibility that multiple pathways, involving ER chaperones, inositol-requiring kinase 1, and protein kinase regulated by RNA-like ER kinase are activated by mutations associated with the infantile form. These results indicate that in Krabbe disease, each misfolded/unfolded protein evokes different UPR activation depending on the mutation, and that the activated pathways affect the phenotypes.

We report the first case of Leigh syndrome (LS) with Fukuyama congenital muscular dystrophy (FCMD). A neonate suffered from lactic acidosis and subsequently presented with poor feeding, muscle weakness, hypotonia, cardiopulmonary dysfunction, and hydrocephalus. He died at 17 months. The findings of brain magnetic resonance imaging indicated some specific features of both LS and FCMD, and FCMD gene mutation was detected. Decreased mitochondrial respiratory complex I and II activity was noted. Mitochondrial DNA sequencing showed no pathogenic mutation. A case with complex I+II deficiency has rarely been reported, suggesting a nuclear gene mutation.

Mucopolysaccharidoses (MPS) are a group of genetic deficiencies of lysosomal enzymes that catabolize glycosaminoglycans (GAG). Here we describe a novel MPS-like disease caused by a specific mutation in the VPS33A gene. We identified several Yakut patients showing typical manifestations of MPS: coarse facial features, skeletal abnormalities, hepatosplenomegaly, respiratory problems, mental retardation, and excess secretion of urinary GAG. However, these patients could not be diagnosed enzymatically as MPS. They showed extremely high levels of plasma heparan sulphate (HS, one of GAG); 60 times the normal reference range and 6 times that of MPS patients. Additionally, most patients developed heart, kidney, and hematopoietic disorders, which are not typical symptoms for conventional MPS, leading to a fatal outcome between 1 and 2-years old. Using whole exome and Sanger sequencing, we identified homozygous c.1492C > T (p.Arg498Trp) mutations in the VPS33A gene of 13 patients. VPS33A is involved in endocytic and autophagic pathways, but the identified mutation did not affect either of these pathways. Lysosomal over-acidification and HS accumulation were detected in patient-derived and VPS33A-depleted cells, suggesting a novel role of this gene in lysosomal functions. We hence propose a new type of MPS that is not caused by an enzymatic deficiency.