Genetic analyses in small-for-gestational-age newborns

Context: Small for gestational age (SGA) can be a result of fetal growth restriction, associated with perinatal morbidity and mortality. Mechanisms that control prenatal growth are poorly understood. Objective: The aim of the present study was to gain more insight into prenatal growth failure and determine an effective diagnostic approach in SGA newborns. We hypothesized that one or more CNVs and disturbed methylation and sequence variants may be present in genes known to be associated with fetal growth. Design: A prospective cohort study of subjects with a low birthweight for gestational age. Setting: The study was conducted at an academic pediatric research institute. Patients: A total of 21 SGA newborns with a mean birthweight below the 1st centile and a control cohort of 24 appropriate for gestational age newborns were studied. Intervention: Array comparative genomic hybridization, genome-wide methylation studies and exome sequencing were performed. Main Outcome Measures: The numbers of copy number variations, methylation disturbances and sequence variants. Results: The genetic analyses demonstrated three CNVs, one systematically disturbed methylation pattern and one sequence variant explaining the SGA. Additional methylation disturbances and sequence variants were present 20 patients. In 19 patients, multiple abnormalities were found. Conclusion: Our results confirm the influence of a large number of mechanisms explaining dysregulation of fetal growth. We conclude that copy number variations, methylation disturbances and sequence variants all contribute to prenatal growth failure. Such genetic workup can be an effective diagnostic approach in SGA newborns.