[A family with early onset myopathy caused by MEGF10 gene defect and literature review]

Objective: To summarize the genetic and clinical phenotypic characteristics of patients with early-onset myopathy, areflexia, respiratory distress and dysphagia (EMARDD) caused by multiple epidermal growth factor 10 (MEGF10) gene defect. Methods: The clinical data of 3 infants in 1 family with EMARDD caused by MEGF10 gene defect diagnosed in the Department of Neonatology, Xiamen Children's Hospital in April 2022 were analyzed retrospectively. Using "multiple epidermal growth factor 10" "myopathy" or "MEGF10" "myopathy" as the key words, and searching the relevant literature reports of CNKI, Wanfang Database and PubMed Database from the establishment of the database to September 2022. Combined with this family, the main clinical information and genotype characteristics of EMARDD patients caused by MEGF10 gene defect were summarized. Results: The proband, male, first infant of monozygotic twins, was admitted to hospital 7 days after birth "due to intermittent cyanosis with weak sucking". The infant had dysphagia accompanied with cyanosis of lips during feeding and crying after birth. Physical examination on admission revealed reduced muscle tone of the extremities, flexion of the second to fifth fingers of both hands with limited passive extension of proximal interphalangeal joints, and limited abduction of both hips. He was diagnosed as dysphagia of newborn, congenital dactyly. After admission, he was given limb and oral rehabilitation training, breathing gradually became stable and oral feeding fully allowed, and discharged along with improvement. The younger brother of the proband was admitted to the hospital at the same time, and his clinical manifestations, diagnosis and treatment process were the same as those of the proband. The elder brother of the proband died at the age of 8 months due to the delayed growth and development, severe malnutrition, hypotonia, single palmoclal crease and weak crying. A whole exon sequencing of the family was done, and found that the 3 children were all compound heterozygous variations at the same site of MEGF10 gene, with 2 splicing variants (c.218+1G>A, c.2362+1G>A), which came from the father and mother respectively, and the new variation was consistent with the autosomal recessive inheritance model. Three children were finally diagnosed as EMARDD caused by MEGF10 gene defect. There are 0 Chinese literature and 18 English literature that met the search conditions. Totally 17 families including 28 patients were reported. There were 31 EMARDD patients including 3 infants from this family. Among them, there were 13 males and 18 females. The reported age of onset ranged from 0 to 61 years. Except for 5 patients with incomplete clinical data, 26 patients were included in the analysis of phenotypic and genotypic characteristics. The clinical features were mainly dyspnea (25 cases), scoliosis (22 cases), feeding difficulties (21 cases), myasthenia (20 cases), and other features including areflexia (16 cases) and cleft palate or high palatal arch(15 cases). Muscle biopsy showed non-specific changes, with histological characteristics ranging from slight muscle fiber size variation to minicores change which was seen in all 5 patients with at least 1 missense mutation of allele. In addition, the adult onset was found in patients with at least 1 missense variant of MEGF10 gene. Conclusions: MEGF10 gene defect related EMARDD can occur in the neonatal period, and the main clinical features are muscle weakness, breathing and feeding difficulties. Patients with myopathy who have at least 1 missense mutation and muscle biopsy indicating minicores change may be relatively mild.