Clinical characteristics and genetic analysis of a Chinese pedigree affected with mitochondrial DNA depletion syndrome due to compound heterozygous variants of RRM2B gene / 中华医学遗传学杂志

ABSTRACT

OBJECTIVE@#To analyze the clinical characteristics and pathogenic gene in a Chinese pedigree affected with mitochondrial DNA depletion syndrome 8A (MTDPS8A).@*METHODS@#Whole exome sequencing was carried out for the patient. Sanger sequencing was used to verify the results, and PolyPhen-2 and PROVEAN software were used to predict the impact of amino acid changes on the function of the protein.@*RESULTS@#The patient, a two-month-old female, was admitted to the hospital for poor milk intake and poor mental response. Her clinical manifestations included feeding difficulty, shortness of breath and low muscle tone. Auxiliary laboratory test indicated that the infant was underdeveloped with abnormal liver, kidney, and heart functions accompanied by hyperlacticacidemia. She responded poorly to treatment and eventually died. Sequencing revealed that the child has carried compound heterozygous missense variants of the RRM2B gene, namely c.16delA (p.R6Gfs*22) and c.175G>C (p.A59P), which were respectively inherited from her father and mother, and both were newly discovered pathologic variants.@*CONCLUSION@#The c.16delA and c.175G>C compound heterozygous variants of the RRM2B gene probably underlay the pathogenesis of MTDPS8A. Above finding has strengthened the understanding of the clinical feature and genetic etiology of this disease and expanded the mutation spectrum of the RRM2B gene.