Microcephalic Osteodysplastic Primordial Dwarfism Type I in Two Siblings Aged 2.5 Years and 18 Gesta- tional Weeks

Microcephalic osteodysplastic primordial dwarfism type I (MOPD I) is a rare autosomal recessive disorder characterized by severe intrauterine growth retardation, microcephaly, facial dysmorphism, central nervous system, skeletal, skin and limb abnormalities. Recently, mutations in RNU4atac SnRNA, a component of the minor spliceosome, have been recognized as the cause of MOPD1. Less than 50 cases have been reported worldwide. We are reporting here a family with two affected offspring, a 2.5 year-old girl with severe microcephaly, short stature, severe flexion contracture of neck, and mental retardation and autopsy findings in an 18-week-old female fetus. Genetic testing of U4atac gene revealed a homozygous r.55G>A mutation in both. These siblings showed severe flexion contracture of neck in addition to the dysmorphic features reported in MOPD1 patients.