Abstract
The purpose of this study is to describe a Mendelian disorder of DNA damage repair. Phenotypic delineation of two families, one new and one previously published, with overlapping dysmorphic and neurodevelopmental features was undertaken. Functional characterization of DNA damage repair in fibroblasts obtained from the index individuals in each of the two families was pursued. We present new evidence of a distinct disorder caused by biallelic truncating variants in ZNF668 comprising microcephaly, growth deficiency, severe global developmental delay, brain malformation, and distinct facial dysmorphism. DNA damage repair defect was observed in fibroblasts of affected individuals. ZNF668 deficiency in humans results in a recognizable autosomal recessive disorder, which we propose to name ZNF668-related ZMAND (ZNF668-related brain malformation, microcephaly, abnormal growth, neurodevelopmental delay, and dysmorphism). Our results add to the growing list of Mendelian disorders of the DNA damage repair machinery.