Background: Familial cases of Henoch-Schönlein purpura (HSP) have rarely been reported.
Methods: Familial cases of HSP were reviewed by medical records of 418 children with HSP.
Results: Two members developed HSP in eight families. HSP occurred in a mother and her daughter in one family and in siblings, including one pair of twin sisters, in seven other families. Four pairs of patients developed HSP at the same age. Three pairs presented HSP within 1 month of each other and the other pairs presented HSP between 9 months and 5 years. Seven patients had a history of allergic diseases. The clinical courses of 12 patients were reviewed. Upper respiratory tract infection preceded HSP in 10 patients, two of whom had elevated antistreptolysin-O titers. No pairs of patients in a family received the same drugs before the onset of HSP. Abdominal pain was noted in eight patients, arthralgia in six and nephritis in four. Severity of skin lesions, presence of abdominal pain and nephritis, and serum IgA levels at the acute stage varied among family members of HSP.
Conclusions: The incidence of HSP in family members of children with HSP seems to be high. Onset at the same age and onset of HSP within 1 month in siblings have not previously been reported. There were no characteristic or similar findings between two patients of the same family. No trigger or genetic factor causing HSP was identified.