Features of BSCL2 related congenital generalized lipodystrophy in China: long-term follow-up of three patients and literature review.

OBJECTIVES: Congenital generalized lipodystrophy (CGL) is a group of rare autosomal inherited diseases characterized by a widespread loss of adipose tissue. The main purpose of this study was to evaluate the features of Chinese patients with CGL2. METHODS: Three patients diagnosed with CGL2 from our center were reviewed. Data on clinical features, results of laboratory analyses, and previous treatments were retrospectively collected. This study also reviewed studies that reported patients diagnosed with CGL2 in the last 30 years. RESULTS: All patients presented a lack of subcutaneous fat, hypertriglyceridemia, reversed triangular faces, acanthosis nigricans, and hepatomegaly within the first six months of life. All three patients developed splenomegaly, and mental retardation in later life. Dietary control dramatically lowered triglyceride levels in all patients. One patient presented with diabetes mellitus at 1 year-old. Although combined therapy with low fat diet and metformin maintained normal levels of blood lipid and glucose, this patient developed hypertrophic cardiomyopathy at the age of three. By a literature review on all Chinese cases with CGL2, it is known that classic manifestations such as hypertriglyceridemia, hepatomegaly and diabetes mellitus can occur shortly after birth, and early diagnosis and treatment can improve quality of life. In this cohort, the most frequent variations are c.782dupG and c.974dup in the BSCL2 gene. However, the same genotype may have different clinical phenotypes in patients with CGL2. CONCLUSIONS: This study not only described the clinical and genetic features of three patients with CGL2 in China, but also reviewed literature about CGL2 around the world.

Mitochondrial FAD shortage in SLC25A32 deficiency affects folate-mediated one-carbon metabolism.

The SLC25A32 dysfunction is associated with neural tube defects (NTDs) and exercise intolerance, but very little is known about disease-specific mechanisms due to a paucity of animal models. Here, we generated homozygous (Slc25a32Y174C/Y174C and Slc25a32K235R/K235R) and compound heterozygous (Slc25a32Y174C/K235R) knock-in mice by mimicking the missense mutations identified from our patient. A homozygous knock-out (Slc25a32-/-) mouse was also generated. The Slc25a32K235R/K235R and Slc25a32Y174C/K235R mice presented with mild motor impairment and recapitulated the biochemical disturbances of the patient. While Slc25a32-/- mice die in utero with NTDs. None of the Slc25a32 mutations hindered the mitochondrial uptake of folate. Instead, the mitochondrial uptake of flavin adenine dinucleotide (FAD) was specifically blocked by Slc25a32Y174C/K235R, Slc25a32K235R/K235R, and Slc25a32-/- mutations. A positive correlation between SLC25A32 dysfunction and flavoenzyme deficiency was observed. Besides the flavoenzymes involved in fatty acid ß-oxidation and amino acid metabolism being impaired, Slc25a32-/- embryos also had a subunit of glycine cleavage system-dihydrolipoamide dehydrogenase damaged, resulting in glycine accumulation and glycine derived-formate reduction, which further disturbed folate-mediated one-carbon metabolism, leading to 5-methyltetrahydrofolate shortage and other folate intermediates accumulation. Maternal formate supplementation increased the 5-methyltetrahydrofolate levels and ameliorated the NTDs in Slc25a32-/- embryos. The Slc25a32K235R/K235R and Slc25a32Y174C/K235R mice had no glycine accumulation, but had another formate donor-dimethylglycine accumulated and formate deficiency. Meanwhile, they suffered from the absence of all folate intermediates in mitochondria. Formate supplementation increased the folate amounts, but this effect was not restricted to the Slc25a32 mutant mice only. In summary, we established novel animal models, which enabled us to understand the function of SLC25A32 better and to elucidate the role of SLC25A32 dysfunction in human disease development and progression.

Clinical and biochemical characteristics of patients with ornithine transcarbamylase deficiency.

BACKGROUND: Ornithine transcarbamylase deficiency (OTCD) is pleomorphic congenital hyperammonemia, in which the prognosis of the patient is determined both by genotype and environmental factors. This study investigated the clinical and biochemical characteristics of OTCD patients with different prognosis. METHOD: Of 35 OTCD patients, six males deceased at the first disease-onset, 17 males survived and had controllable ammonia levels after treatment, and 12 females survived through the first disease-onset but had intractable hyperammonemia and high mortality. Fasting blood samples from patients collected at three disease stages were used for the analysis of amino acid (AA) profile, acylcarnitine profile, and micronutrients. Differences in profiles between patients and healthy controls and within patient groups were studied. RESULTS: All OTCD patients had accumulation of glutamine, homocitrulline, lysine, glutamate, cystathionine, and pipecolic acid, as well as deficiency of citrulline, tryptophan, threonine, and carnitine. For male non-survivors, most other AAs and long-chain acylcarnitines were elevated at disease onset, of which the levels of creatine, N-acetylaspartic acid, and homoarginine were remarkably high. Male survivors and female patients had most other AAs at low to normal levels. Compared with male survivors, female patients had much lower protein-intolerance, as indicated by significantly lower levels of protein consumption indicators, including essential AAs, 1-methylhistidine, acylcarnitines et al., but high levels of ammonia. Female patients still had significantly higher levels of citrulline, homocitrulline, and citrulline/arginine compared to male survivors. CONCLUSION: Unique profiles were observed in each group of OTCD patients, indicating specific physiological changes that happened to them.

Clinical Management and Gene Mutation Analysis of Children with Congenital Hyperinsulinism in South China

Objective: To explore the clinical presentation and molecular genetic characteristics of a cohort of congenital hyperinsulinism (CHI) patients from southern China and also to explore the most appropriate therapeutic approaches. Methods: We retrospectively reviewed a cohort of 65 children with CHI. Mutational analysis was performed for KCNJ11 and ABCC8 genes. The GLUD1 gene was sequenced in patients with hyperammonaemia. GCK gene sequencing was performed in those patients with no mutation identified in the ABCC8, KCNJ11 or GLUD1 genes. Results: ABCC8 mutations were identified in 16 (25%) of the cohort, GLUD1 mutations were identified in five children, and no KCNJ11 or GCK mutations were identified. Moreover, some unique features of ABCC8 gene mutations in southern Chinese CHI patients were found in this study. The most common mutation was a deletion/insertion mutation p.Thr1042GlnfsX75 was found in five unrelated patients, which possibly represents a relatively common mutation in southern China. Five novel ABCC8 mutations were detected. The mutations were p.Phe5SerfsX72, p.Gln273ArgfsX85, p.Leu724del, p.Asp1447Gly and IVS 25-1G>T. Five compound heterozygous mutations of ABCC8 gene were identified in this study, and three of these patients were diazoxide-responsive. Forty patients were diazoxide-responsive, 13 patients were diazoxide-unresponsive and 12 patients received dietary treatment only. A pancreatectomy was performed in 10 patients who were unresponsive to medical treatment. Conclusion: To the best of our knowledge, this is the first study of CHI in south China. Mutations in ABCC8 are the most common causes of CHI in this cohort. Diazoxide and dietary treatment were effective in most patients. Multicentre studies are necessary to obtain the long-term follow-up characteristics of such patients at a national level.

Clinical features and mutational analysis in 114 young children with Wilson disease from South China.

Wilson disease (WD) is a rare autosomal recessive disorder caused by mutations in the ATP7B gene. Clinical features and mutational analysis of Chinese children with WD at early age were rarely described. Herein, we retrospectively examined 114 children with WD at the mean of 5.9 years old age at diagnosis. Eight patients developed acute liver failure at mean age of 9.7 years old, 4 of whom died. Among the 114 patients, 86.0% were presymptomatic with isolated elevation of transaminases at diagnosis, 99.1% had decreased ceruloplasmin, and 68.4% had urinary copper excretion over 100 µg/24 hr. Bi-allele pathogenic ATP7B mutations were identified in all patients. Among the 60 mutations detected, 10 were novel, including 7 missense mutations (p.I566N, p.T704I, p.C980F, p.G1030 V, p.A1096Q, p.L1327P, and p.L1373F), 1 nonsense mutation (p.K866X), 1 small insertion (p.Y44LfsX2), and 1 small deletion (p.R1118PfsX10). The most frequent mutations were p.R778L, p.P992L, and p.I1148T, which affected 27.2, 25.4, and 20.2% of the 114 WD children, respectively. The patients carrying p.R778L presented a higher rate of acute liver failure than the patients without p.R778L (9.7% vs. 4.8%). These results will be helpful in establishing early diagnosis of WD at the gene level, offering beneficial information for genetic counseling and providing clues to genotype/phenotype correlation of ATP7B mutations.

Clinical features, molecular characteristics, and treatments of a Chinese girl with sitosterolemia: A case report and literature review.

Sitosterolemia is a rare autosomal recessive disease characterized by a significant increase in blood plant sterol levels. Clinical manifestations usually include xanthomas, hypercholesterolemia,premature atherosclerosis and hematological abnormalities. We report here a sitosterolemia patient who presented with multiple xanthomas and profound hypercholesterolemia since 3 years old. The girl was mistreated as familial hypercholesterolemia for 6 years until correct diagnosis was made by detecting serum plant cholesterol levels. Sequence analysis revealed compound heterozygous mutations in ABCG5 gene, including the previously reported mutation c.904+1G＞A and a novel missense mutation c.1528C＞A. Although cholestyramine therapy reduced cholesterol level in association with marked regress of the xanthomas, serum plant sterol levels still remain high. Our study suggests that patients develop severe hypercholesterolemia and xanthomas at early age should be suspected of sitosterolemia. In addition, we also describe a novel missense mutation in exon 11 of the ABCG5 gene, which enriches the genetic mutation spectrum of sitosterolemia.

Early prenatal diagnosis of lysosomal storage disorders by enzymatic and molecular analysis.

OBJECTIVE: To report the 4-year experience of early prenatal diagnosis of lysosomal storage disorders (LSDs) at a center in mainland China. METHOD: Forty-seven pregnancies affected with LSDs were assed using enzymes and/or molecular studies. Prenatal studies were performed on 43 uncultured chorionic villi (CV) samples, two amniotic fluid samples, and two umbilical cord blood samples. RESULTS: Of the 47 fetuses, 23 (48.9%) were determined to normal, 13 (27.7%) to be carriers, and 11 (23.4%) diagnosed as affected. In this cohort, mucopolysaccharidoses (MPS) type II was the most common LSD, followed by Pompe disease and then metachromatic leucodystrophy. In the 17 MPS II cases, the four affected fetuses showed MPS II enzyme activity expression levels of 1.4% to 6.7%, while the enzyme activity levels of the 13 normal fetuses ranged from 72% to 240.4%. In the seven Pompe cases, three fetuses were normal with Pompe enzyme activity expression levels of 20%, 38.8%, and 77.3%, while four carrier pregnancies showed enzyme activity levels of 17.5%, 17.5%, 33.4%, and 13.8%, respectively. CONCLUSION: Based on different enzyme properties in uncultured CV, different prenatal diagnostic strategies should be adopted for MPS II and Pompe disease. Combining enzyme assay and molecular studies in uncultured CV improves the reliability of prenatal diagnosis of LSDs.

Brain abnormalities in fucosidosis: transplantation or supportive therapy?

Fucosidosis is a rare lysosomal storage disease caused by α-fucosidase deficiency, which leads to progressive neurological deterioration and death. Hematopoietic stem cell transplantation is the best curative therapy if performed during the early stages of disease. We report two fucosidosis patients with brain abnormalities and the challenge faced in their management. The first patient received supportive therapy and the second one firstly underwent unrelated donor umbilical cord blood transplantation. After a period of follow-up, we found neurological symptoms were worsening day by day on patient1. By contrast, patient2 who received cord blood transplantation acquired clinical neurologic improvement in response to normalization of deficient enzymatic activity. This report indicates that hematopoietic transplant could reduce the severity and retard the progression of clinical neurological deterioration. Umbilical cord blood transplantation is a novel approach for treating fucosidosis patients who lack suitable bone morrow donors.

Discovery of a phosphodiesterase 9A inhibitor as a potential hypoglycemic agent.

Phosphodiesterase 9 (PDE9) inhibitors have been studied as potential therapeutics for treatment of diabetes and Alzheimer's disease. Here we report a potent PDE9 inhibitor 3r that has an IC50 of 0.6 nM and >150-fold selectivity over other PDEs. The HepG2 cell-based assay shows that 3r inhibits the mRNA expression of phosphoenolpyruvate carboxykinase and glucose 6-phosphatase. These activities of 3r, together with the reasonable pharmacokinetic properties and no acute toxicity at 1200 mg/kg dosage, suggest its potential as a hypoglycemic agent. The crystal structure of PDE9-3r reveals significantly different conformation and hydrogen bonding pattern of 3r from those of previously published 28s. Both 3r and 28s form a hydrogen bond with Tyr424, a unique PDE9 residue (except for PDE8), but 3r shows an additional hydrogen bond with Ala452. This structure information might be useful for design of PDE9 inhibitors.