Genetically Confirmed Familial Case of Nonsyndromic Cardiac Progeria Caused by the LMNA p.Asp300Asn Variant with Presumed Gonadal Mosaicism: Phenotypic Comparison with Previously Reported Patients

We describe the first genetically confirmed familial case of nonsyndromic cardiac progeria caused by the <i>LMNA</i> NM_170707.4:c.898G>A (p.Asp300Asn) variant, with evidence suggesting gonadal mosaicism as the mechanism of inheritance. The proband developed severe early-onset valvular and coronary artery disease requiring multiple surgical interventions, yet showed no systemic progeroid features. Genetic analysis revealed the heterozygous variant in her unaffected daughters and nieces but not in either parent. Comparison with previously reported cases highlights striking clinical heterogeneity associated with this variant, ranging from isolated cardiovascular involvement to syndromic progeroid manifestations with metabolic and skeletal abnormalities. This variability likely reflects the combined influence of genetic, epigenetic, and environmental factors. Our case expands the clinical spectrum of <i>LMNA</i> p.Asp300Asn and underscores the importance of considering laminopathies in patients with unexplained early-onset cardiac disease. Early genetic diagnosis is essential for the management, surveillance, and counseling of affected families.