Abstract: 【Abstract】 To report the first domestic case of congenital ichthyosis with woolly hair and elucidate its genetic variant profile. A 28-year-old female presented with rash on the trunk and limbs at birth. Dermatological examination revealed generalized dry and rough skin with well-defined, dark brown, polygonal adherent scales densely distributed over the trunk and extremities. No significant abnormalities were observed in the mucous membranes, teeth, or nails. The patient exhibited evenly distributed hair with a soft, dry, and woolly curly texture, normal hair density, and no obvious hair breakage or brittleness, though the eyebrows were sparse. Hair microscopy showed irregular axial twisting at varying intervals under optical microscopy, while scanning electron microscopy revealed irregular hair shaft morphology with some segments appearing flattened in a "belt-like" pattern. Magnification further demonstrated cuticle damage, including localized lifting and longitudinal grooves, indicating structural hair shaft defects. Whole-exome sequencing identified a homozygous variant （c.124dupC） in exon 3 of the PRSS8 gene, resulting in a frameshift mutation （p.Gln42Profs*24） in the PRSS8 protein. According to ACMG guidelines and the patient's clinical presentation, this variant was preliminarily classified as pathogenic. A diagnosis of syndromic ichthyosis was made. This case represents the first reported instance in China and the second internationally of a novel syndromic ichthyosis caused by PRSS8 gene mutation. We propose designating this condition as "ichthyosis-woolly hair syndrome," underscoring the critical role of proteases in epidermal barrier function and hair follicle development.

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