ABSTRACT
Objective:To summarize the clinical manifestations of a case of combined oxidative phosphorylation deficiency 28 (COXPD-28) caused by the mutations of the SLC25A26 gene, thus providing references for the diagnosis and genetic counseling of the disease. Methods:Clinical data of a case of COXPD-28 treated in the Third Affiliated Hospital of Zhengzhou University in October 2020 were retrospectively analyzed.In addition, The retrieval words " Combined oxidative phosphorylation deficiency 28, SLC25A26 gene" were used to search domestic and foreign databases.The clinical characteristics of combined phosphorylation deficiency 28 and the variation characteristics of SLC25A26 gene were summarized. Results:(1) A female patient full-term delivered after 30 min presented with groaning breath was admitted.Her main manifestations included pale complexion, groaning breathing, metabolic acidosis, and high lactate and pyruvate levels.Symptomatic support treatment like anti-infection and assisted ventilation were given, but her condition gradually worsened and died of respiratory and circulatory failure on the day of admission.The child was compound heterozygous mutation of SLC25A26 gene, the terminating mutation of exon 5 c. 403G>T caused the protein change to p. E135, and the non-synonymous mutation of exon 4 c. 212A>G caused the protein change to p. Y71C.(2) A total of 3 cases of COXPD-28 were searched in online databases, and no cases were reported in China.Through literature review, clinical features of COXPD-28 mainly included respiratory and circulatory fai-lure, elevations of lactate and pyruvate, and reductions of complexes Ⅰ, Ⅲ and Ⅳ in muscle biopsy.Two types of mutations in the SLC25A26 gene were detected, including 3 cases of missense mutations and 1 case of splicing mutation. Conclusions:COXPD-28 is an autosomal recessive genetic disease involving multiple systems and mitochondrial dysfunction.Mutations in the SLC25A26 gene is the pathological cause of COXPD-28.
ABSTRACT
Objective:To report a case of combined oxidative phosphorylation deficiency 28 (COXPD28) in China, identified the pathogenic mutation and explored the pathogenic mechanism preliminarily.Methods:The clinical characteristics of a patient with COXPD28 were retrospectively analyzed and the pathogenic mutations were identified by mitochondrial gene sequencing and whole exome sequencing. The wild-type and mutant plasmids of pathogenic genes were constructed, and effect of mutation on protein expression by quantitative real-time PCR (qPCR) and Western blot were evaluated. Statistical methods mainly used one-way ANOVA and LSD test.Results:A 21 year old female patient presented with lactic acid poisoning due to repeated chest distress and wheezing since childhood. The sequencing of the whole exon group gene found that solute carrier family 25 member 26 (SLC25A26) gene had a compound heterozygous mutation (c.34G>C, p.A12P; c.197C>A, p.A66E), which was the first report in China. In vitro function test showed that the expression levels of SLC25A26 mRNA and S-adenosylmethionine carrier (SAMC) protein in cells transfected with SLC25A26 mutant plasmid were significantly lower than those transfected with wild type plasmid. The p.A66E mutant plasmid reduced the expression level of SLC25A26 mRNA and SAMC protein to 6% and 26% of wild type plasmids respectively (both P<0.001), while p.A12P mutant plasmid decreased to 62% and 82% of wild type plasmids respectively ( P<0.001, P=0.044). When the double mutant (p.A66E+p.A12P) plasmids were co-transfected, the expression levels of SLC25A26 mRNA and SAMC protein decreased to 47% and 57% of the wild type plasmids, respectively ( P<0.001, P=0.001). Conclusion:The pathogenic mutation gene of this patient with COXPD28 is SLC25A26 gene mutation (p.A66E, p.A12P), which causes the decrease of SLC25A26 expression level, mitochondrial oxidative phosphorylation dysfunction, and induces COXPD28.