Partial trisomy 6p: 46,XX, -10, der(10),t(6;10) (p22;q26)pat and HLA localisation.

A child with multiple facial anomalies showed partial trisomy 6p, 46,XX, -10,der(10), t(6;10)(p22;q26)pat. Family studies suggested that the HLA complex is probably between 6p22.4 and 6p21.05. The HLA system had previously been localised between 6p21 and 23(12) and more precisely located by Berger et al3 above 6p21.05. We have studied the clinical presentation and the HLA system of the family of a child with partial trisomy 6p derived from a paternal translocation. Since Breuning et al4 collected and studied the first six known cases of trisomy 6p, 12 cases have been found with similar clinical manifestations, varying in the breakpoint and the part of 6p which was triplicated. Independent of the classification of the clinical manifestations of new syndromes, the importance of duplication-deficiency chromosomal abnormalities is determined by the localised of gene loci. The HLA system was localised by Berger et al3 at above 6p21.05. Our results suggest that the HLA system is below 6p22.4, the breakpoint found in the balanced translocation 6p22;10q26 of the father which produced the partial trisomy 6p22 leads to pter of the proband.