Expanding the Progeroid Laminopathy Spectrum: Clinical Variability and Later-Onset Phenotype in Homozygous LMNA c.1579C>T (p.Arg527Cys) Associated Mandibuloacral Dysplasia.

Homozygous LMNA c.1579C>T p.(Arg527Cys) has previously been reported in seven families and is associated with a progeroid phenotype intermediate between Hutchinson-Gilford progeria syndrome (HGPS) and mandibuloacral dysplasia type A (MAD-A). Due to the limited number of reported cases, the complete phenotypic spectrum associated with this variant remains poorly understood. Here, we describe two Syrian siblings born to consanguineous parents, both homozygous for the LMNA p.Arg527Cys variant. Unlike previously reported cases, these siblings demonstrated a notably delayed onset of clinical symptoms. Both patients exhibited severe generalized lipodystrophy, pronounced progeroid facial dysmorphism, mandibular hypoplasia with severe micrognathia, and pan-digital acro-osteolysis. Our findings expand the recognized clinical spectrum associated with the homozygous LMNA p.Arg527Cys variant and illustrate intrafamilial variability in age of onset within an otherwise relatively homogeneous phenotype.