Abstract:

Objective To provide thinking and measures for early diagnosis by exploring the relations between clinical characteristics, laboratory examination and genotypes of cblC type methylmalonic acidemia.Methods The data of clinical manifestation, gene results, tandem mass spectrometry, imageological examination of 19 children with methylmalonic acidemia admitted to the Department of Pediatric Endocrinology and Growth Development, the Second Hospital of Hebei Medical University from 2016 to 2020 were retrospectively analyzed. Results There were 10 male and 9 female patients in out of 19 cases, of which 8 cases were confirmed by neonatal screening. A total of 13 mutations were found by genetic testing, the most common mutations satisfied c.609G>A, followed by the mutations satisfying c.80A>G and c.656_ c.658delAGA. Initial neurological symptoms of 11 cases who were not confirmed by neonatal screening were feeding difficulties, developmental delay, poor response, visual impairment, convulsions, etc. C3 /C0, C3 /C2, urinary methylmalonic acid and homocysteine were significantly elevated in tandem mass spectrometry. Laboratory testing data showed that multiple organs were damaged involving the blood system, nervous and digestive systems, etc. Conclusion The clinical manifestations and laboratory examination of children with cblC type methylmalonic acidemia demonstrate diversely with poor specificity. The genotypes showing the termination or frame-shift mutation normally develop early and have relatively severe symptoms may be show severe neurological complications including the hydrocephalus. The late-onset conditions are mild and have better prognosis by early treatment. late-onset disease of children is easily ignored normally, causing delayed diagnosis on pathogenetic condition. It is necessary to take early diagnosis on cblC type methylmalonic acidemia Attributing to great improvements of the condition and prognosis. Neonatal tandem mass spectrometry screening makes for the early diagnosis, and genotype detection contribute to specific disease classification and targeted treatment, thereby reducing the disability rate and mortality of the disease.

Key words: methylmalonic acidemia, MMACHC gene, methylmalonic acid