A novel <i>LSS</i> variant leading to hypotrichosis with pseudoainhum

Congenital alopecia/hypotrichosis constitutes a spectrum of rare inherited hair disorders characterized by partial to complete alopecia and possible structural hair shaft defects. The lanosterol synthase (LSS) gene, implicated in cholesterol biosynthesis, has emerged as a novel genetic determinant of congenital hypotrichosis. This article describes a 43-year-old female with congenital lanugo-like scalp hair and absence of eyebrows who later developed painful fibrotic constrictive bands on her fingers, culminating in pseudoainhum, but without manifestations of typical palmoplantar keratoderma (PPK). Whole-exome sequencing detected a novel homozygous variant (c.508G>A; p. Asp170Asn) in the LSS gene. This case delineates an atypical LSS variant presentation associated with pseudoainhum phenotype, manifesting without classic PPK features, a previously unreported phenotypic combination. Our findings expand the phenotypic spectrum of LSS-related disorders and underscore the potential role of lipid signaling in hair follicle biology and the pseudoainhum phenomenon.