Neonatal maple syrup urine disease in China: two novel mutations in the BCKDHB gene and literature review

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Hong‐Hua Jiang ◽  
Yan Guo ◽  
Xian Shen ◽  
Ying Wang ◽  
Ting-Ting Dai ◽  
...  
Keyword(s):  
Maple Syrup Urine Disease ◽  
Chinese Literature ◽  
Brain Mri ◽  
Classical Type ◽  
Novel Mutations ◽  
Maple Syrup ◽  
Gene Testing ◽  
Urine Disease ◽  
Bckdhb Gene ◽  
Branched Chain

Abstract Objectives To report two novel mutations in the BCKDHB gene with Maple syrup urine disease (MSUD) and compare their data with 52 cases of MSUD reported in the available Chinese literature. Methods Clinical data of a case of a newborn with MSUD was retrospectively studied. Literatures on MSUD in the local medical journals from January 1990 till December 2019 in China were reviewed. Results Two novel BCKDHB mutations c.90_91insCTGGCGCGGGG (p.Phe35TrpfsTer41) and c.80_90del (p.Ala32PhefsTer48) were identified. We found a total of 52 cases of MSUD reports so far. A total of 49 cases had the symptom of poor feeding (94.2%), 50 cases showed poor responses to stimulation (96.2%), 21 cases had odor of maple syrup (40.3%), 29 cases had seizures (55.7%), and 13 cases had respiratory failure (25.0%). The average of the blood ammonia was 127.2 ± 75.0 μmol/L. A total of 18 cases reported the gene testing, among of them 9 cases of BCKDHA mutations, 6 cases of BCKDHB mutations, and 2 cases of DBT mutations. A total of 13 cases (25%) were treated with mechanical ventilation, 50 cases (96.2%) with protein-restricted diet and l-carnitine, 29 cases with thiamine, and only 2 cases were treated with blood purification. Finally, 19 patients (36.5%) were died, 21 cases (40.4%) were improved after treatments. Conclusions The clinical phenotype of neonatal MSUD in China belongs to the classical type currently. Suspected patients should have blood or urine branched-chain amino acid levels tested and brain MRI as early as possible to enable early diagnosis, thus improvement in prognosis.

scholarly journals Maple syrup urine disease: magnetic resonance imaging findings in three patients

2021 ◽  
pp. 1-11
Author(s):  
Aliya Allahwala ◽  
Sibtain Ahmed ◽  
Bushra Afroze
Keyword(s):  
Magnetic Resonance Imaging ◽  
Amino Acids ◽  
Magnetic Resonance ◽  
Maple Syrup Urine Disease ◽  
Brain Mri ◽  
Brain Magnetic Resonance Imaging ◽  
Resonance Imaging ◽  
Maple Syrup ◽  
Urine Disease ◽  
Branched Chain

Abstract Maple syrup urine disease (MSUD) is an autosomal recessive inherited metabolic disorder, caused by branched-chain alpha-ketoacid dehydrogenase (BCKD) deficiency, leading to toxic accumulation of branched-chain amino acids (BCAAs) including leucine, isoleucine and valine and their corresponding ?-ketoacids. The diagnosis of MSUD is based on elevated BCAAs and allo-isoleucine in plasma, and branched-chain hydroxyacids and ketoacids in urine. The identification of alloisoleucine >5 µmol/L is considered pathognomonic. Moreover, brain magnetic resonance imaging (MRI) showing atypical signal intensity and oedema is characteristic of MSUD. Recognition of the classical neuro-radiological findings of MSUD is particularly useful in local settings as many healthcare facilities lack the resources to measure Plasma Amino Acids (PAA). We report three cases of MSUD, in whom the disorder was strongly suspected at presentation, based on classical brain MRI findings, which was urgently confirmed by PAA analysis Continuous...

Four novel mutations of the BCKDHA, BCKDHB and DBT genes in Iranian patients with maple syrup urine disease

2018 ◽  
Vol 31 (2) ◽  
pp. 205-212 ◽  
Author(s):  
Monica Zeynalzadeh ◽  
Alireza Tafazoli ◽  
Azadeh Aarabi ◽  
Morteza Moghaddassian ◽  
Farah Ashrafzadeh ◽  
...  
Keyword(s):  
Maple Syrup Urine Disease ◽  
Energy Levels ◽  
Clinical Manifestations ◽  
Autosomal Recessive Disorder ◽  
Strong Correlations ◽  
Novel Mutations ◽  
Maple Syrup ◽  
Urine Disease ◽  
Branched Chain ◽  
Ketoacid Dehydrogenase

Abstract Background: Maple syrup urine disease (MSUD) is a rare metabolic autosomal recessive disorder caused by dysfunction of the branched-chain α-ketoacid dehydrogenase (BCKDH) complex. Mutations in the BCKDHA, BCKDHB and DBT genes are responsible for MSUD. The current study analyzed seven Iranian MSUD patients genetically and explored probable correlations between their genotype and phenotype. Methods: The panel of genes, including BCKDHA, BCKDHB and DBT, was evaluated, using routine the polymerase chain reaction (PCR)-sequencing method. In addition, protein modeling (homology and threading modeling) of the deduced novel mutations was performed. The resulting structures were then analyzed, using state-of-the-art bioinformatics tools to better understand the structural and functional effects caused by mutations. Results: Seven mutations were detected in seven patients, including four novel pathogenic mutations in BCKDHA (c.1198delA, c.629C>T), BCKDHB (c.652C>T) and DBT (c.1150A>G) genes. Molecular modeling of the novel mutations revealed clear changes in the molecular energy levels and stereochemical traits of the modeled proteins, which may be indicative of strong correlations with the functional modifications of the genes. Structural deficiencies were compatible with the observed phenotypes. Conclusions: Any type of MSUD can show heterogeneous clinical manifestations in different ethnic groups. Comprehensive molecular investigations would be necessary for differential diagnosis.

scholarly journals Hereditary characteristics of the S339L mutation in a patient with maple syrup urine disease in Vietnam

2020 ◽  
Vol 42 (2) ◽  
Author(s):  
Nguyen Thi Thu Huong ◽  
Vu Chi Dung ◽  
Nguyen Thi Thanh Ngan ◽  
Nguyen Kim Thoa ◽  
Nguyen Huy Hoang
Keyword(s):  
Amino Acids ◽  
Maple Syrup Urine Disease ◽  
Neurological Complications ◽  
Scientific Basis ◽  
Homozygous Mutation ◽  
Maple Syrup ◽  
Urine Disease ◽  
Bckdhb Gene ◽  
Branched Chain ◽  
Ketoacid Dehydrogenase

Maple syrup urine disease (MSUD) is an autosomal recessive inherited metabolic disorder caused by malfunction of the branched-chain α-ketoacid dehydrogenase complex (BCKDH). This enzyme complex participates in the catalyzing metabolisms of the branched-chain α-ketoacids, the second step of the degradation of branched-chain amino acids. Impaired activities of the BCKAD complex lead to an increase of the levels of branched- chain amino acid such as leucine, valine, and isoleucine in the blood. In children with maple syrup urine disease, catalysis of the metabolisms of some amino acids failed to be implemented, leading to an accumulation of the amino acids which has been shown as one of the causes of neurological complications, intellectual disabilities, and nervous paralysis or even death. Pathogenic mutations normally occur in BCKDHA, BCKDHB, DBT and DLD genes which encode the E1α, E1β, and E2 subunits of the BCKDH complex. In the present study, a homozygous mutation in the BCKDHB gene (c. 1016C>T) in a pediatric patient with MSUD diagnosed at The National Hospital of Pediatrics was identified using whole exome and Sanger sequencing methods. As a result, the inheritance of the homozygous mutation related to MSUD in BCKDHB gene within the pedigree of the patient’s family was determined. The results indicated that the mutation in the BCKDHB gene was inherited from both of the patient’s parents. In addition, this finding provides an important scientific basis to  researches on MSUD in the Vietnamese population. 

scholarly journals Genetic analysis by targeted next-generation sequencing and novel variation identification of maple syrup urine disease

2021 ◽  
Author(s):  
Xiaohua Fang ◽  
Xiaofan Zhu ◽  
Yin Feng ◽  
Ying Bai ◽  
Xuechao Zhao ◽  
...  
Keyword(s):  
Maple Syrup Urine Disease ◽  
Mainland China ◽  
Autosomal Recessive Disorder ◽  
Maple Syrup ◽  
Targeted Next Generation Sequencing ◽  
Coding Regions ◽  
Targeted Ngs ◽  
Urine Disease ◽  
Bckdhb Gene ◽  
Branched Chain

Abstract Maple syrup urine disease (MSUD) is a rare autosomal recessive disorder that affects the degradation of branched chain amino acids (BCAAs). Only a few cases of MSUD have been documented in Mainland China. In this report, 8 patients (4 girls and 4 boys) with MSUD from 8 unrelated Chinese families were diagnosed at the age of 9 days to 1 year and 8 months. All the coding regions and exon/intron boundaries of BCKDHA, BCDKHB, DBT, DLD genes were analyzed by targeted NGS in the 8 MSUD pedigrees. Targeted NGS revealed 2 pedigrees with MSUD Ia, 5 pedigrees with Ib, 1 pedigree with MSUD II. Totally, 13 variants were detected, including 2 variants (p.Ala216Val and p.Gly281Arg) in BCKDHA gene，10 variants (p.Gly95Ala, p.Ser171Pro, p.Phe175Leu, p.Arg183Trp, p.Lys222Thr, p.Arg285Ter，p.Arg111Ter，p.S184Pfs*46, p.Arg170Cys, p.I160Ffs*25) in BCKDHB gene, 1 variants (p.Arg431Ter) in DBT gene. In addition, 4 previously unidentified variants (p.Gly281Arg in BCKDHA gene, p.Ser171Pro, p.Gly95Ala and p.Lys222Thr in BCKDHB gene) were found. NGS plus Sanger sequencing detection is effective and accurate for making gene diagnosis. Computational structural modeling indicated that these novel variations might affect structural stability.

scholarly journals Two novel mutations in the BCKDHB gene that cause maple syrup urine disease

2018 ◽  
Vol 59 (5) ◽  
pp. 515-519 ◽  
Author(s):  
Bingjuan Han ◽  
Bingchao Han ◽  
Bin Guo ◽  
Yingxia Liu ◽  
Zhiyang Cao
Keyword(s):  
Maple Syrup Urine Disease ◽  
Novel Mutations ◽  
Maple Syrup ◽  
Urine Disease ◽  
Bckdhb Gene

Two novel mutations in the BCKDHB gene (R170H, Q346R) cause the classic form of maple syrup urine disease (MSUD)

Gene ◽  
2012 ◽  
Vol 498 (1) ◽  
pp. 112-115 ◽  
Author(s):  
Yue-Ping Wang ◽  
Man-Long Qi ◽  
Ting-Ting Li ◽  
Yun-Jing Zhao
Keyword(s):  
Maple Syrup Urine Disease ◽  
Novel Mutations ◽  
Maple Syrup ◽  
Urine Disease ◽  
Bckdhb Gene ◽  
Classic Form

scholarly journals Challenges in Diagnosing Intermediate Maple Syrup Urine Disease by Newborn Screening and Functional Validation of Genomic Results Imperative for Reproductive Family Planning

2021 ◽  
Vol 7 (2) ◽  
pp. 25
Author(s):  
Mona Sajeev ◽  
Sharon Chin ◽  
Gladys Ho ◽  
Bruce Bennetts ◽  
Bindu Parayil Sankaran ◽  
...  
Keyword(s):  
Newborn Screening ◽  
Maple Syrup Urine Disease ◽  
Dietary Intervention ◽  
Brain Mri ◽  
Prenatal Testing ◽  
Intermediate Form ◽  
Motor Delay ◽  
Maple Syrup ◽  
Hyperintense Signal ◽  
Urine Disease

Maple syrup urine disease is caused by a deficiency of branched-chain alpha-ketoacid dehydrogenase, responsible for degradation of leucine, isoleucine, and valine. Biallelic pathogenic variants in BCKDHA, BCKDHB, or DBT genes result in enzyme deficiency. We report the case of a female infant who presented with mild gross motor delay at 4 months, and seizures with hypoglycaemia at 5 months. Newborn screening returned total leucine/isoleucine at the 99.5th centile of the population; however, as second-tier testing reported minimal alloisoleucine, the results were considered inconsistent with MSUD. Plasma amino acid and urine organic acid analyses at 5 months were, however, consistent with a diagnosis of MSUD. A brain MRI showed bilateral symmetrical T2 hyperintense signal abnormalities involving white matter, globus pallidus, thalamus, brainstem, and dentate nuclei with restricted diffusion. A repeat MRI 10 months post-dietary-intervention showed the resolution of these changes and progression in myelination. Her clinical phenotype, including protein tolerance, correlated with intermediate MSUD. Molecular analysis of all three genes identified two variants of uncertain significance, c.434-15_434-4del and c.365A>G (p. Tyr122Cys) in the DBT gene. The rate of leucine decarboxylation in fibroblasts was reduced, but not to the extent observed in classical MSUD patients, supporting an intermediate form of MSUD. Previously reported mRNA splicing studies supported a deleterious effect of the c.434-15_434-4del variant. This functional evidence and confirmation that the variants were in trans, permitted their reclassification as pathogenic and likely pathogenic, respectively, facilitating subsequent prenatal testing. This report highlights the challenges in identifying intermediate MSUD by newborn screening, reinforcing the importance of functional studies to confirm variant pathogenicity in this era of molecular diagnostics.

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