PHOSPHOMANNOMUTASE 2-CONGENITAL DISORDER OF GLYCOSYLATION: A CASE REPORT AND LITERATURE REVIE

Abstract

Objective To investigate the clinical and genetic features of patients with phosphomannomutase 2 (PMM2)-congenital disorder of glycosylation (CDG), and to provide a basis for the early diagnosis of PMM2-CDG. Methods A retrospective analysis was performed for the clinical data of a child with PMM2-CDG admitted to our hospital, and CNKI, Wanfang Data, VIP, and PubMed were searched to analyze the clinical data of Chinese patients with PMM2-CDG. Results The child in this study had the clinical manifestations of growth retardation, delayed gross motor development, rash, hypotonia, and abnormal liver aminotransferases. High-throughput genome sequencing revealed a homozygous mutation, c.634A>G, in the PMM2 gene, which came from the parents. After the diagnosis was clarified, the child was given supportive therapy such as feeding and nutrition gui-dance, liver-protecting treatment, and mannose supplementation and was asked to attend the hospital for regular reexamination. Liver transaminases returned to normal at 6 months of age, and the child gradually developed the unusual facies of wide forehead at 1 year of age. The child was followed up to the age of 2 years and 6 months and showed no improvement in growth retardation, and delayed development gradually became more obvious. Most of the 21 Chinese patients with PMM2-CDG in the above database had the manifestations of growth retardation, delayed development, and hypotonia, with the presence of cerebellar dysplasia on cranial imaging examination, and c.395T>C(p.I132T) and c.430T>C(p.P144L) are common mutations in Chinese patients with PMM2-CDG. Conclusion PMM2-CDG is a rare congenital autosomal recessive metabolic disease, and PMM2 gene testing should be performed for patients with related symptoms to make a confirmed diagnosis.

Keywords

• congenital disorders of glycosylation|phosphotransferases (phosphomutases)|mannose|mutation|genetic testing|retrospective studies