Uncombable Hair Syndrome Due to Maternal Uniparental Disomy of Chromosome 1

This study reports a case of uncombable hair syndrome (UHS) in a 23-month-old girl, caused by a homozygous PADI3 variant due to maternal uniparental disomy (UPD) of chromosome 1. The diagnosis was confirmed through clinical examination, electron microscopy, and whole exome sequencing. The patient's hair exhibited typical UHS features, including frizzy, light blonde hair that could not be managed. The study highlights that UPD should be considered in cases of homozygous recessive diseases like UHS. The recurrence risk is low, and no additional pathogenic variants were found in the homozygous regions of chromosome 1.