Clinical and genetic analysis of a case of dihydrolipoamide dehydrogenase deficiency caused by novel variant of DLD gene / 中华医学遗传学杂志

OBJECTIVE@#To analyze the clinical and genetic characteristics of a patient with dihydrolipoamide dehydrogenase deficiency.@*METHODS@#Potential variants of the DLD gene were detected by whole exome sequencing and verified by Sanger sequencing.@*RESULTS@#Compound heterozygous variants, c.704_705delTT (p.Leu235Argfs*8) and c.1058T>C (p.Ile353Thr), were detected in the DLD gene. The c.1058T>C (p.Ile353Thr) variant was derived from his mother and known to be pathogenic. The c.704_705delTT (p.Leu235Argfs*8) variant was derived from his father and was unreported previously.@*CONCLUSION@#The compound heterozygous variants of c.704_705delTT (p.Leu235Argfs*8) and c.1058T>C (p.Ile353Thr) of the DLD gene probably underlay the disease in this patient. Above finding has facilitated genetic counseling and prenatal diagnosis for the family.

Maple syrup urine disease in Brazil: a panorama of the last two decades / Doença da urina de xarope de bordo no Brasil: um panorama das últimas duas décadas

OBJECTIVE: To characterize a sample of Brazilian patients with maple syrup urine disease (MSUD) diagnosed between 1992 and 2011. METHODS: In this retrospective study, patients were identified through a national reference laboratory for the diagnosis of MSUD and through contact with other medical genetics services across Brazil. Data were collected by means of a chart review. RESULTS: Eighty-three patients from 75 families were enrolled in the study (median age, 3 years; interquartile range [IQR], 0.57-7). Median age at onset of symptoms was 10 days (IQR 5-30), whereas median age at diagnosis was 60 days (IQR 29-240, p = 0.001). Only three (3.6%) patients were diagnosed before the onset of clinical manifestations. A comparison between patients with (n = 12) and without (n = 71) an early diagnosis shows that early diagnosis is associated with the presence of positive family history and decreased prevalence of clinical manifestations at the time of diagnosis, but not with a better outcome. Overall, 98.8% of patients have some psychomotor or neurodevelopmental delay. CONCLUSION: In Brazil, patients with MSUD are usually diagnosed late and exhibit neurological involvement and poor survival even with early diagnosis. We suggest that specific public policies for diagnosis and treatment of MSUD should be developed and implemented in the country. .

OBJETIVO: Caracterizar uma amostra de pacientes brasileiros com a doença da urina de xarope de bordo (DXB) diagnosticados entre 1992 e 2011. MÉTODOS: Os pacientes foram identificados por meio de um laboratório de referência nacional para o diagnóstico de DXB e por meio do contato com outros serviços de genética médica no Brasil. Os dados foram coletados por meio de uma revisão de prontuários. RESULTADOS: Foram incluídos no estudo 83 pacientes de 75 famílias (idade média: três anos; intervalo interquartil (IQR): 0,57-7). A idade média no surgimento dos sintomas era de 10 dias (IQR: 5-30), ao passo que a idade média no diagnóstico era de 60 dias (IQR: 29-240; p = 0,001). Somente três (3,6%) pacientes foram diagnosticados antes do surgimento de manifestações clínicas. Uma comparação entre pacientes com (n = 12) e sem (n = 71) um diagnóstico precoce mostra que o diagnóstico precoce está associado à presença de histórico familiar positivo e à redução na prevalência de manifestações clínicas no momento do diagnóstico, porém sem melhor resultado. Em geral, 98,8% dos pacientes têm algum atraso no desenvolvimento psicomotor ou neurológico. CONCLUSÃO: No Brasil, os pacientes com DXB normalmente recebem um diagnóstico tardio e exibem um envolvimento neurológico e baixa sobrevivência, mesmo com um diagnóstico precoce. Sugerimos que políticas públicas específicas para o diagnóstico e tratamento da DXB sejam desenvolvidas e implementadas no país. .

Analysis of gene mutations among South Indian patients with maple syrup urine disease: Identification of four novel mutations.

Maple syrup urine disease (MSUD) is predominantly caused by mutations in the BCKDHA, BCKDHB and DBT genes, which encode for the E1α, E1β and E2 subunits of the branched-chain α-keto acid dehydrogenase complex, respectively. Because disease causing mutations play a major role in the development of the disease, prenatal diagnosis at gestational level may have significance in making decisions by parents. Thus, this study was aimed to screen South Indian MSUD patients for mutations and assess the genotype-phenotype correlation. Thirteen patients diagnosed with MSUD by conventional biochemical screening such as urine analysis by DNPH test, thin layer chromatography for amino acids and blood amino acid quantification by HPLC were selected for mutation analysis. The entire coding regions of the BCKDHA, BCKDHB and DBT genes were analyzed for mutations by PCR-based direct DNA sequencing. BCKDHA and BCKDHB mutations were seen in 43% of the total ten patients, while disease-causing DBT gene mutation was observed only in 14%. Three patients displayed no mutations. Novel mutations were c.130C>T in BCKDHA gene, c. 599C>T and c.121_122delAC in BCKDHB gene and c.190G>A in DBT gene. Notably, patients harbouring these mutations were non-responsive to thiamine supplementation and other treatment regimens and might have a worse prognosis as compared to the patients not having such mutations. Thus, identification of these mutations may have a crucial role in the treatment as well as understanding the molecular mechanisms in MSUD.

Enzymatic method for branched chain alpha-ketoacid determination: application to rapid analysis of urine and plasma samples from maple syrup urine disease patients

A new method for the determination of branched-chain alpha-ketoacid concentration using lactate dehydrogenase (E C 1.1.1.27) isozyme C4 (LDH) C4) from mouse testes is proposed. The assay is performed on urine and plasma without previous treatment. Alpha-ketoglutarate and pyruvate are determined on the same sample using glutamate dehydrogenase (GDH,EC 1.4.1.2) and lactate dehydrogenase isozyme A4 (LDH5) respectively and subtracted from the total alpha-ketoacid concentration obtained with LDH C4. This value corresponds to the branched chain alpha-ketoacid. Results were linear within the concentration range 8 to 170 mumoles/L. Detection limit was 8 mumoles/L. Analytical recovery was higher than 91 per cent. For microplate assays, recoveries were higher than 84 per cent and the detection limit was 20 mumoles/L. Determinations performed with GDH, LDH A4 and LDH C4 allow differentiation of E3 deficiency from other clinical phenotypes of maple syrup urine disease. The method is simple and fast, and adaptation to microplates would allow screening of newborns.

Maple syrup urine disease: case report of 2 Thai infants.

Maple syrup urine disease (MSUD) is a rare inborn error of metabolism characterized by typical urine odor. The deficiency of branched-chain ketoacid decarboxylase enzyme is responsible for the clinical abnormalities. The classical disease usually manifests in the neonatal period with lethargy, refused feeding, seizures and death. Since 1984, at the Department of Pediatrics, Ramathibodi hospital, 2 patients with classical MSUD have been seen. The parents of one patient were relatives and already had 2 affected but undiagnosed daughters. Both patients had strong urine odor which was described as the odor of boiled Chinese herbal medicine. The first child died at 4 months old and the second was severely retarded at one year old. The importance of early diagnosis and genetic counselling are emphasized.