MEFV and familial Mediterranean fever: The frequency of MEFV gene mutation in Egyptian patients with HSP in the present work (61.7%) is very close to its frequency in Egyptian children with FMF, reported as (57.6%) in the study of El Gezery et al. [17] and 60.5% in the work of Ibrahim et al. [18], but lower than the frequency in the work of El Garf et al. (97%) [19].