Lamins are nuclear intermediate filaments that, together with lamin-associated proteins, maintain nuclear shape and provide a structural support for chromosomes and replicating DNA. We have determined the solution structure of the human lamin A/C C-terminal globular domain which contains specific mutations causing four different heritable diseases. This domain encompasses residues 430-545 and adopts an Ig-like fold of type s. We have also characterized by NMR and circular dichroism the structure and thermostability of three mutants, R453W and R482W/Q, corresponding to "hot spots" causing Emery-Dreifuss muscular dystrophy and Dunnigan-type lipodystrophy, respectively. Our structure determination and mutant analyses clearly show that the consequences of the mutations causing muscle-specific diseases or lipodystrophy are different at the molecular level.