The use of X-STRs in the investigation of complex kinship cases.

BOBILLO C; MARINO M; A, SALA; GUSMAO L; CORACH D

Copenhague (Dinamarca).

Congreso; XII Jornadas del GEP-ISFG; 2007

Grupo español y Portugues-ISFG

Human identification analysis is a highly standardized routine procedure, performed by autosomal STR typing, occasionally complemented by Y-STRs and mtDNA studies. In spite of the high discrimination power and sensitivity of STRs, there are some instances whose results are inconclusive. Recent update of X-STRs provide a complementary tool, if the disputed child is a girl. The aim of this work is to underscore the applicability of the X-STRs for clarifying unsolved cases. Two sample sets were selected. Case 1: a maternity case involving a girl, her alleged father and two putative, full sibs, mothers. Originally tested with 21 STRs (PP16, Indentifiler, F13AO1 F13B, LPL, FES/FPS,) and HVRI/II mtDNA sequencing to confirm matrilineage. The father was excluded and the maternity test inconclusive. Case 2: a deficient incest case including three full sibs, a man and two women, and a daughter of one of them. The man who fathered the three offsprings was accused to fathered the daughter, but his sample was unavailable. STR results were inconclusive. Both cases were further investigated by 10 X-STRs: DXS8378, DXS9898, DXS7133, GATA31E08, GATA172DO5, DXS7423, DXS6809, DXS7132, DXS9902 and DXS6789. X-chromosome ability to recombine in females is the clue for investigating the first case. In the other case, the male unrecombined X chromosome transmission to all their daughters, allowed to exclude the supposed incest case.