A Case of Monozygotic Twins Carrying a Novel Loss-of-Function Variant in the MYCBP2 Gene, Presenting With Microcephaly, Ectopic Kidney and Growth Restriction.

What is already known about this topic? ◦. Pathogenic variants in the MYCBP2 gene are associated with neurodevelopmental disorders, congenital heart disease, skeletal and ocular anomalies, and cancers. However, reports on the prenatal phenotypes of fetuses carrying MYCBP2 variants remain rare. What does this study add? ◦. A novel de novo heterozygous MYCBP2 variant c.3421C > T p.(Arg1141Ter) was identified and confirmed as pathogenic. This variant expands the known MYCBP2 variant spectrum. The presence of microcephaly, ectopic kidney and growth retardation in fetuses with MYCBP2 variants expands the prenatal phenotypic spectrum.