Identification of the first congenital ichthyosis case caused by a homozygous deletion in the gene due to chromosome 17 mixed uniparental disomy.

Uniparental disomy (UPD) is a rare genetic event caused by errors during gametogenesis and fertilization leading to two copies of a chromosome or chromosomal region inherited from one parent. MixUPD is one type of UPD that contains isodisomic and heterodisomic parts because of meiotic recombination. Using whole-exome sequencing (WES), we identified the first case of ichthyosis due to a maternal mixUPD on chromosome 17, which results in a homozygous deletion of partial intron 8 to exon 10 in , being predicted to lead to an internal protein deletion of 97 amino acids. We also performed a retrospective analysis of 198 patients with mutations. The results suggested that the exon 9 and 10 are located in the mutational hotspots of . In addition, our patient has microtia and congenital stenosis of the external auditory canals, which is very rare in patients with mutations. Our study reports the first case of autosomal recessive congenital ichthyosis (ARCI) due to a mixUPD of chromosome 17 and expands the spectrum of clinical manifestations of ARCI caused by mutations in the gene.