Marker segregation in an Arab GT family near the IIb-β3 genomic locus. The extensive family tree for one of the studied families with the determined inherited markers (Table 2) are shown. Crossover regions are shown on a black background. The inherited thrombasthenia gene is also indicated by the grayed regions in the family tree over the affected chromosome. The polymorphic markers studied are indicated at the top left of the fig and refer to Table2.