Concurrent Chondrodysplasia Punctata Type 2 (Conradi–Hunermann–Happle Syndrome) and Ichthyosis Vulgaris in Teenaged Twin Girls

We present concurrent X-linked chondrodysplasia punctata and ichthyosis vulgaris in adolescent fraternal twin girls, notable for initial presentation with dry skin in adolescence, characterized by dark-brown scale typical of ichthyosis vulgaris and blaschkolinear, atrophic, scaly plaques. This constellation of findings prompted further genetic investigation. Using a multigene approach to examine 39 genes associated with congenital ichthyosis, next-generation sequencing revealed a novel heterozygous missense mutation at a mutational hotspot in the EBP gene c.439C>T (p.R147C) in conjunction with a single nonsense mutation in the FLG gene (p.R501X) in both sisters. These individuals highlight the clinical variability of Conradi–Hunermann–Happle syndrome, illustrate the possibility of co-occurrence of rare and common forms of ichthyosis, and demonstrate the utility of multigene analysis.