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Objective:To investigate the incidence rate and gene variation of methylmalonic academia (MMA) in Ji′nan city by analyzing biochemical and genetic screening results, and to explore the carrier frequency of MMA-related pathogenic genes in the population in Ji′nan.Methods:The children diagnosed with MMA by tandem mass spectrometry screening in Ji′nan Neonatal Disease Screening Centre from May 2011 to May 2022 were enrolled in this study.Their genetic test results were retrospectively analyzed and summarized.The dried heel blood tablets collected from 6 800 newborns were tested for neonatal gene screening. MMAA, MMAB, MMACHC and MMUT genes in 4 800 cases were detected by high-throughput sequencing+ target area capture technology.Ultra-multiplex polymerase chain reaction+ target gene locus capture technology was used to detect 174 target loci of 8 genes related to MMA in 2 000 cases.The hotspot mutation and related gene carrier rate of MMA were analyzed. Results:A total of 367 452 newborns were screened by tandem mass spectrometry, and 103 cases (56 males and 47 females) were diagnosed with MMA by screening.The estimated incidence of MMA was 1∶3 567.Among the 103 MMA cases, 76 were genetically diagnosed, and 4 gene variants of MMA ( MMAHC, MMUT, MMAA, MMADHC) were identified.A total of 6 800 neonates underwent neonatal genetic screening.Three of them were diagnosed with MMA.About 318 infants carried pathogenic variants of MMA, with a total carrier rate of 4.68%.Specifically, the carrier rates of MMACHC and MMUT gene variants were 3.09%(210/6 800) and 1.43% (97/6 800), respectively. Conclusions:MMA is the most common organic acid metabolism disorder in our country.The incidence and carrier rate of this disease are high in Jinan city.Neonatal genetic screening is an important supplement to neonatal biochemical screening.Carrier screening for MMA-related pathogenic genes is recommended for couples of childbearing age in Jinan.
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OBJECTIVES@#To retrospectively analyze the variation and characteristics of phenylalanine hydroxylase (PAH) gene, and to observe the long-term treatment effect and follow-up of newborns with PAH deficiency.@*METHODS@#Clinical data, treatment and follow-up results of 198 patients with PAH deficiency diagnosed by newborn screening in Jinan from 1996 to 2021 were collected. The genetic analysis of 55 patients with PAH deficiency diagnosed by newborn screening in Jinan and 213 patients referred from the surrounding areas of Jinan were summarized. Gene variations were checked by a customized Panel gene detection method. Blood phenylalanine-concentration and physical development indicators including height and weight were regularly monitored. Intellectual development was assessed using a neuropsychological development scale for patients aged 0-6 years and academic performance, and brain injury in patients was assessed using brain magnetic resonance imaging.@*RESULTS@#c.728G>A, c.158G>A, c.721C>T, c.1068C>A, c.611A>G variations were common in PAH gene. The genotype of c.158G>A variation is compound heterozygous variation, with mainly a mild hyperpheny-lalaninemia. 168 patients with PAH deficiency who were followed-up regularly had normal physical development without dwarfism or malnutrition. Among the 33 preschool patients who underwent mental development assessment, 2 were mentally retarded and the initial treatment age was older than 6 months. Nine patients with an average age of (17.13±2.42) years completed brain magnetic resonance imaging, one case was normal, and 8 cases were abnormal. There were patchy or patchy hyperintense foci near the bilateral lateral ventricles on T2WI, and the intellectual development was normal. Compared with the other eight patients, the blood phenylalanine concentration of the normal child was better and stably controlled within the ideal range.@*CONCLUSIONS@#c.728G>A, c.158G>A, c.721C>T, c.1068C>A, c.611A>G variations were common in PAH gene. After standardized treatment, most patients with PAH deficiency diagnosed by screening can obtain normal growth and intellectual development in adolescence, but there are different degrees of organic lesions in the cerebral white matter.