Abstract: 【Abstract】 To report the first case of congenital ichthyosis with woolly hair in China, and to elucidate its genetic variant profile. A 28-year-old female patient presented with rashes on the trunk and limbs for 28 years. Dermatological examination revealed dry and rough skin over the entire body, with well-defined, polygonal, dark brown, adherent scales densely distributed over the trunk and extremities. No significant abnormalities were observed in the mucous membranes, teeth, or nails. The patient exhibited uniformly distributed, woolly and curly hair with a soft, dry texture and normal density; no significant hair breakage or brittleness was observed, while the eyebrows appeared sparse. Hair microscopy showed irregular axial twisting of hair strands at varying intervals; scanning electron microscopy （SEM） revealed irregular hair shafts with some segments appearing flat in a belt-like pattern, and magnified SEM images further demonstrated hair cuticle damage on the surface of hair shafts, manifesting as localized upward curling and longitudinal grooves, indicating structural damage to the hair shafts. Whole-exome sequencing identified a homozygous variant c.124dupC in exon 3 of the PRSS8 gene in the proband, resulting in a frameshift mutation （p.Gln42Profs*24） in the PRSS8 protein. According to the guidelines of the American College of Medical Genetics and Genomics as well as the patient's clinical manifestations, this variant could be preliminarily classified as pathogenic. A diagnosis of syndromic ichthyosis was made. This case represents the first report of syndromic ichthyosis caused by PRSS8 variants in China and the second report in the world, and this condition is proposed to be tentatively named as "ichthyosis-woolly hair syndrome".

Key words: Ichthyosis vulgaris, Ichthyosiform erythroderma, congenital, PRSS8 gene, woolly hair