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Clinical picture and treatment effects in 5 patients with Methylmalonic aciduria related to MMAA mutations.

ABSTRACT: Introduction:Methylmalonic Aciduria (MMA) is a heterogeneous group of rare diseases leading to accumulation of methylmalonic acid in body fluids. One of the causes of the disease is the methylmalonic aciduria, cblA type (cblA - type MMA), conditioned by a mutation in the MMAA gene, which is essential for the proper functioning of a cofactor of the methylmalonyl-CoA mutase. The symptoms of the disease, depending on the cause, may manifest themselves at different ages. Most patients are sensitive to high doses of hydroxycobalamin, which is associated with better prognosis. Material and method:The purpose of the study was to retrospectively analyze the clinical picture and effects of treatment of patients with methylmalonic aciduria related to mutation in the MMAA gene. Results:Five patients with diagnosed cblA - type MMA were presented. At the time of diagnosis the median of age was 18.8?months, but the symptoms had already appeared since infancy, as recurrent vomiting and delayed psychomotor development. Significant excretion of methylmalonic acid in urine and metabolic acidosis traits with significantly increased anionic gap were observed in all patients. All of them were sensitive to the treatment with vitamin B12. The median of therapy duration and observation is 12.2?years. During the treatment, good metabolic control was achieved in all patients, but their cognitive development is delayed. Three patients have renal failure and pharmacologically treated arterial hypertension. Conclusions:Patients with a mutation in the MMAA gene are sensitive to treatment with hydroxocobalamine, but the inclusion of appropriate treatment does not protect against neurodevelopmental disorders and chronic kidney disease.

SUBMITTER: Wesol-Kucharska D

PROVIDER: S-EPMC6950841 | biostudies-literature | 2020 Mar

REPOSITORIES: biostudies-literature

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Clinical picture and treatment effects in 5 patients with Methylmalonic aciduria related to <i>MMAA</i> mutations.

Wesół-Kucharska Dorota D Kaczor Magdalena M Pajdowska Magdalena M Ehmke Vel Emczyńska-Seliga Ewa E Bogdańska Anna A Kozłowski Dariusz D Piekutowska-Abramczuk Dorota D Ciara Elżbieta E Rokicki Dariusz D

Molecular genetics and metabolism reports 20200108

<h4>Introduction</h4>Methylmalonic Aciduria (MMA) is a heterogeneous group of rare diseases leading to accumulation of methylmalonic acid in body fluids. One of the causes of the disease is the methylmalonic aciduria, cblA type (<i>cblA</i> - type MMA), conditioned by a mutation in the <i>MMAA</i> gene, which is essential for the proper functioning of a cofactor of the methylmalonyl-CoA mutase. The symptoms of the disease, depending on the cause, may manifest themselves at different ages. Most p ...[more]

PMID: 31921599

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Project description:BackgroundIsolated methylmalonic aciduria can be caused by pathogenic mutations in the gene for methylmalonyl-CoA mutase or in the genes encoding enzymes involved in the intracellular metabolism of cobalamin. Some of these mutations may be cobalamin responsive. The type of methylmalonic aciduria cannot always be assumed from clinical manifestation and the responsiveness to cobalamin has to be assessed for appropriate cobalamin administration, or to avoid unnecessary treatment. The cases presented herein highlight the importance of genetic testing in methylmalonic aciduria cases and the need for standardisation of the in vivo cobalamin-responsiveness assessment.Case presentationWe describe two patients who presented in the first week of life with rapid neurological deterioration caused by metabolic acidosis with severe hyperammonaemia requiring extracorporeal elimination in addition to protein restriction, energy support, carnitine, and vitamin B12 treatment. The severity of the clinical symptoms and high methylmalonic acid concentrations in the urine (>30,000 μmol/mmol of creatinine) without hyperhomocysteinaemia in both of our patients suggested isolated methylmalonic aciduria. Based on the neonatal manifestation and the high methylmalonic acid urine levels, we assumed the cobalamin non-responsive form. The in vivo test of responsiveness to cobalamin was performed in both patients. Patient 1 was evaluated as non-responsive; thus, intensive treatment with vitamin B12 was not used. Patient 2 was responsive to cobalamin, but the dose was decreased to 1 mg i.m. every two weeks with daily oral treatment due to non-compliance. Genetic tests revealed bi-allelic mutations in the genes MMAB and MMAA in Patient 1 and 2, respectively. Based on these results, we were able to start intensive treatment with hydroxocobalamin in both patients. After the treatment intensification, there was no acute crisis requiring hospitalisation in Patient 1, and the urine methylmalonic acid levels further decreased in Patient 2.ConclusionsDespite carrying out the in vivo test of responsiveness to cobalamin in both patients, only the results of molecular genetic tests led us to the correct diagnosis and enabled intensive treatment with hydroxocobalamin. The combination of the standardized in vivo test of cobalamin responsiveness and genetic testing is needed for accurate diagnosis and appropriate treatment of isolated methylmalonic aciduria.

Project description:BACKGROUND:Methylmalonic acidemia (MMA) is an autosomal recessive inherited disorder caused by complete or partial deficiency of the enzyme methylmalonyl-CoA mutase (mut0 enzymatic subtype or mut- enzymatic subtype, respectively); a defect in the transport or synthesis of its cofactor, adenosyl-cobalamin (cblA, cblB, or cblD-MMA); or deficiency of the enzyme methylmalonyl-CoA epimerase. The cblA type of MMA is very rare in China. This study aimed to describe the biochemical, clinical, and genetic characteristics of two siblings in a Chinese family, suspected of having the cblA-type of MMA. METHODS:The Chinese family of Han ethnicity of two siblings with the cblA-type of MMA, was enrolled. Target-exome sequencing was performed for a panel of MMA-related genes to detect causative mutations. The influence of an identified missense variant on the protein's structure and function was analysed using SIFT, PolyPhen-2, PROVEAN, and MutationTaster software. Moreover, homology modelling of the human wild-type and mutant proteins was performed using SWISSMODEL to evaluate the variant. RESULTS:The proband was identified via newborn screening (NBS); whereas, her elder brother, who had not undergone expanded NBS, was diagnosed later through genetic family screening. The younger sibling exhibited abnormal biochemical manifestations, and the clinical performance was relatively good after treatment, while the older brother had a mild biochemical and clinical phenotype, mainly featuring poor academic performance. A novel, homozygous missense c.365T>C variant in exon 2 of their MMAA genes was identified using next-generation sequencing and validated by Sanger sequencing. Several different types of bioinformatics software predicted that the novel variant c.365T>C (p.L122P) was deleterious. Furthermore, three-dimensional crystal structure analysis revealed that replacement of Leu122 with Pro122 led to the loss of two intramolecular hydrogen bonds between the residue at position 122 and Leu188 and Ala119, resulting in instability of the MMAA protein structure. CONCLUSIONS:The two siblings suspected of having the cblA-type of MMA showed mild phenotypes during follow-up, and a novel, homozygous missense variant in their MMAA genes was identified. We believe that the clinical features of the two siblings were associated with the MMAA c.365T>C variant; however, further functional studies are warranted to confirm the variant's pathogenicity.

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Clinical picture and treatment effects in 5 patients with Methylmalonic aciduria related to MMAA mutations.

Publications

Clinical picture and treatment effects in 5 patients with Methylmalonic aciduria related to <i>MMAA</i> mutations.

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