Clinical and variant analysis of 15 patients with methylmalonic acidemia / 中华医学遗传学杂志

Objective@#To report on clinical characteristics and genetic findings in 15 Chinese patients with methylmalonic acidemia (MMA).@*Methods@#For the 15 MMA patients detected by tandem mass spectrometry, genetic analysis was carried out in twelve pedigrees. Clinical characteristics, genetic finding, treatment and outcomes were retrospectively analyzed.@*Results@#The main features of the patients included poor feeding, recurrent vomiting, lethargy, seizure and development retardation. Blood propionylcarnitine (except for 3 patients), its ratio with acetylcarnitine, and urine methylmalonic acid were increased in all patients. Twelve patients were diagnosed genetically, which included 7 with MUT variants, 4 with MMACHC variants, and 1 with MMAB variant. Nine MUT variants were detected, among which c. 1159A>C, 753+ 1delGinsTGGTTATTA and c. 504del were novel. Six known pathogenic MMACHC variants and two novel MMAB variants (c.289_290delGG, c. 566G>A) were also detected. Seven patients died of metabolic crises within a year, others had improved effectively following the treatment, but had mild to severe growth delay and/or developmental retardation.@*Conclusion@#The clinical manifestation of MMA are complex. Most patients have variants of the MUT and MMACHC genes. High mortality may occur before one year of age.

Identification of a novel frameshift mutation (L345Sfs*15) in a Korean neonate with methylmalonic acidemia

Methylmalonic acidemia (MMA) is an autosomal recessive metabolic disorder characterized by an abnormal accumulation of methylmalonyl-CoA and methylmalonate in body fluids without hyperhomocysteinemia. Cardiac disease is a rarely known lethal complication of MMA, herein, we report a Korean neonate diagnosed with MMA on the basis of biochemical and genetic findings, who developed cardiomyopathy, resulting in sudden death. The patient presented vomiting and lethargy at 3 days of age. Initially, the patient had an increased plasma propionylcarnitine/acetylcarnitine concentration ratio of 0.49 in a tandem mass spectrometry analysis and an elevated ammonia level of 537 µmol/L. Urine organic acid analysis showed increased excretion of methylmalonate. Subsequent sequence analysis of the methylmalonyl-CoA mutase (MUT) gene revealed compound heterozygous mutations c.323G>A (p.Arg108His) in exon 1 and c.1033_1034del (p. Leu345Serfs*15) in exon 4, the latter being a novel mutation. In summary, this is the first case of MMA and cardiomyopathy in Korea that was confirmed by genetic analysis to involve a novel MUT mutation.

Methylmalonic aciduria combined with congenital adrenal hyperplasia:a case report / 临床儿科杂志

Objective To explore the diagnosis and treatment of a rare case of methylmalonic aciduria combined with congenital adrenal hyperplasia. Methods The clinical and laboratory data of the first case of methylmalonyl CoA mutase deifcient methylmalonic aciduria combined with 21-hydroxylase deifciency in China were analyzed. Results The male patient with age of onset at 3 months presented with feeding dififculty, diarrhea, metabolic acidosis, and psychomotor retardation after polio vaccination or high protein diet. At one year and 8 months of age, methylmalonic aciduria was diagnosed, and the patient was clinically improved after treatment. At 5 years of age, precocious puberty was noticed, and virilizing form of 21-Hydroxylase deifciency was diagnosed. Genetic testing conifrmed 2 known mutations in MUT gene (c.866G?>?C, c.2179C?>?T) and 2 known mutations in CYP21A2 gene (c.188A?>?T, c.518T?>?A). Conclusions The clinical manifestations of inherited metabolic disorders and endocrine diseases are complex and it is rare that multiple disorders occurred simultaneously in one patient. This male patient has two rare diseases, methylmalonic aciduria and 21-hydroxylase deifciency.

Clinical Characteristics and Gene Mutation Analysis of Methylmalonic Aciduria / 华中科技大学学报（医学）（英德文版）

Methylmalonic aciduria (MMA) is a common inherited autosomal recessive disorder resulting from defects in the enzyme methylmalonyl CoA mutase (MCM,mut complementation group) or in the synthesis of the MCM cofactor adenosylcobalamin (cbl complementation groups).The defects in the mut complementation group accounts for the largest number of patients with isolated MMA.At least 200 mutations in the MUT gene on chromosome 6p12 have been identified in MMA patients until now.This study aimed to investigate the clinical characteristics of MMA and genomic variations in the MUT gene of Chinese patients.Genomic DNA was extracted from 18 patients who were diagnosed as having isolated MMA by gas chromatography/mass spectrometry (GC-MS),and from some of their parents as well.Amplification and direct sequencing of the MUT coding regions (exon 2-13) and their adjacent intronic consensus splice sites were performed in order to identify the disease causing mutations.In this group,six novel mutations in the MUT gene,c.424A＞G (p.T142A),c.786T＞G (p.S262R),c.808G＞C(p.G270R),c.1323_1324insA,c.1445-1G＞A and c.1676+77A＞C were identified.p.T142A and p.G270R were respectively detected at a heterozygous level in one patient.Two previously reported mutations,c.682C＞T (p.R228X) and c.323G＞A (p.R108H) were also found in this study.In addition,six previously described single nucleotide polymorphism (SNP),c.636A＞G (p.K212K),c.1495G＞A(p.A499T),c.1595A＞G (p.H532R),c.1992G＞A (p.A664A),c.2011G＞A (p.V671I) and c.1677-53A＞Gwere identified.In this study,we updated the spectrum of MUT mutations and identified the main MMA-causing mutations in Chinese MMA patients.

Novel mutation of methylmalonyl-CoA mutase gene in a Thai infant with methylmalonic acidemia (mut0).

Isolated methylmalonic acidemia is found in patients with mutations in the MUT gene causing partial methylmalonyl CoA mutase deficiency, mut-, or complete methylmalonyl CoA mutase deficiency, mut0. Most mut0 patients have an earlier and more severe presentation than the other groups such as mut- and cbl defect. We report a 6-month-old Thai male presenting with wide-anion gap metabolic acidosis after acute lower respiratory infection. Urine organic acids analysis demonstrated excretions of methylmalonic acid and methylcitrate, consistent with methylmalonic acidemia. He was then started on low protein diet with an appropriate metabolic formula, L-carnitine (100 mg/kg/day), and oral vitamin B12 (1 mg/day). He had only one single metabolic episode at 2 years of age. At present, he is doing well with normal growth and development. His methylmalonyl-CoA mutase activity was undetectable compatible with mut0. He was found to be homozygous for a novel IVS11-2A>G mutation causing two aberrantly spliced transcripts. The identified mutation and enzyme activity of this patient should cause severe phenotype, although, our patient has milder clinical manifestations. Therefore we hypothesize that there are other factors that may determine the clinical phenotype of mutase deficiency in the present case.