Characterisation and validation of a novel panel of the six short tandem repeats for genetic counselling in Chinese haemophilia A pedigrees.

Haemophilia A (HA) is the most common hereditary bleeding disorder caused by F8 gene mutation. Linkage analysis is an auxiliary strategy to direct mutation analysis for genetic counselling of HA. Here we characterize and validate a novel panel of six short tandem repeat (STR) loci for genetic counselling in Chinese HA pedigrees. The panel was analysed in 116 unrelated healthy female patients and 108 male patients, and verified in 169 unrelated pedigrees with HA. The six STR loci in the panel spanned a distance of 0.3 Mb from each side of the F8 gene. Three of them, F8Up226, F8Up146 and F8Down48, were first described here. Markers F8Up226, F8Up146, F8Int13, F8Int25, F8Down48 and DXS1073 exhibited the number of alleles 16, 9, 8, 6, 9 and 10, and heterozygosity rates of 74.8%, 44.8%, 60.9%, 42.6%, 61.7% and 62.0% respectively. Haplotype frequencies analysis suggested that the genotypes of haplotype provided a highly informative content (56.5%). The panel was informative in 167 of 169 unrelated haemophilic pedigrees with the combined diagnostic rate of 98.8%. In eight pedigrees could not be diagnosed by mutation detection linkage studies using the panel were informative in all the pedigrees and a reliable diagnosis was made in seven pedigrees. The novel panel of the six STR loci represents a high degree of informativeness and a low fraction of recombination. Linkage analysis using this panel provides an alternative strategy when direct mutation detection is not feasible for genetic counselling in Chinese HA families.