Familial occurrence of progressive systemic sclerosis and systemic lupus erythematosus.

Eight families containing one member with progressive systemic sclerosis and another with systemic lupus erythematosus have been encountered. Two individuals had clinical/serologic/postmortem findings of both diseases and familial pairs were generally concordant for serologic features. A general lack of household contact was encountered, and HLA haplotypes were shared in 5 of 6 pairs studied.