Complete commissural agenesis in a child with Noonan-like syndrome with loose anagen hair 2.

Abstract

RASopathies are a wide group of multisystemic disorders caused by pathogenic variants in genes belonging to the RAS/MAPK pathway. Among these, PPP1CB gene variants cause Noonan syndrome-like disorder with loose anagen hair 2 (NSLAH2), a rare condition with neuro-cardio-facio-skeletal involvement and the peculiar loose anagen hair. We report on a girl carrying the recurrent c.146 C > G (p.Pro49Arg) pathogenic variant, who presented the classical NSLH features associated with a previously unreported complete commissural agenesis, likely expanding the phenotype. The prominent role of Ras protein in oligodendrocyte maturation and differentiation might lend biological plausibility to the myelination impairment observed in our patient.