Extended family studies for the identification of allogeneic stem cell transplant donors in Jewish and Arabic patients in Israel.

HLA-identified donors are the best source of allogeneic hematopoietic stem cell transplants, and are available in approximately 40% of cases. If no HLA-identical core family member is found, an extended family search may be performed. The aim of the study was to summarize the 10-year (1990-1999) experience of our tertiary care center with extended family donor search. During this period, 356 patients and 2659 of their family members were tissue-typed; 239 patients were Jewish (67%) and 117 were Arabic (33%). An HLA-identical core-family donor was identified for 168 patients (47%): 95 Jewish (40%) and 73 Arabic (62%) (p < 0.0001); 49 patients (14%) had more than one potential donor. An extended family search (grandmother/grandfather, aunts, uncles, etc.) was performed in 38 of the remaining families, which were found to be consanguineous: five Jewish and 33 Arabic. One HLA match was found in the Jewish families (20%) and 21 in the Arabic families (64%). The odds ratio for an Arabic patient to find a donor in the extended family search was 8.75, as opposed to a Jewish patient. Overall, HLA-matched donors were found by core and extended family search for 53% of the patients. The rate for Arabic patients was 80% and for Jewish patients, 40% (p < 0.001). This difference may be explained by the greater number of siblings and higher rate of consanguinity in the Arabic population. In conclusion, an extended family search for potential HLA-matched donors is worthwhile, especially in distinct ethnic populations with high consanguinity, such as Israeli Arabs.