Abstract: Objective To investigate the serological and molecular genetic characteristics of individuals with p blood type of Lahu and their family members. Methods Blood samples from family members of 6 cases with p blood type previously found in Lahu population were collected, and ABO, Rh, P1PK blood group system serological identification was performed by test tube method, and the coding region sequences of A4GALT gene were analyzed by PCR sequencing. Results Among 39 family members from 5 families, 12 cases p blood type individuals (including 6 previously identified probands) were detected, all of them were p blood type, including 7 cases of type B, 2 cases of type O, 1 case of type A, 1 case of type AB, and 1 case of undetected ABO blood group. Anti-PP₁P^k antibodies were detected in the plasma of 11 individuals with p blood type, 1 case collected by finger blood and no antibodies were detected. Sequencing of A4GALT gene coding region was performed on 23 of the family members whose venous blood was collected. The sequencing results of 11 cases showed homozygous mutations of G>C at position 559 of exon 3 of A4GALT (including 6 previously identified probands), were p blood type, and 5 cases showed heterozygous mutations of 559G/C. Sequencing of 7 cases was consistent with the reference series. Conclusion The mutation of A4GALT gene C.559G >C may be the molecular basis for the formation of p blood group in Lahu population.

Key words: Lahu nationality, p blood type, Family investigation, P1PK blood group, Anti-PP₁P^k, A4GALT gene