Early Diagnosis of 3M Syndrome Accompanying Hirschsprung Disease in a Neonate: A Case Report

3M syndrome is a rare disease characterized by severe growth retardation, characteristic facial morphology, and skeletal abnormalities. Approximately 65% of patients with 3M syndrome have mutations in the cullin-7 (CUL7) gene. We report a rare case of early diagnosis of 3M syndrome in a newborn with Hirschsprung disease. A female infant was born at 38 weeks and 3 days of gestation with a birth weight of 2,510 g. The patient had a large forehead, round face, short extremities, and a small body. The patient had abdominal distension and delayed meconium passage for over 48 hours. Hirschsprung disease was diagnosed, and the patient underwent surgical treatment. Next-generation sequencing analysis of the patient showed a CUL7 gene mutation, which suggested a diagnosis of 3M syndrome. We confirmed a compound heterozygous CUL7 gene mutation by genetic testing of the parents. In the future, the patient needs to be repeatedly assessed for growth, development, and skeletal deformities and will be treated with growth hormone therapy at an outpatient clinic.