A genetic linkage study of choroideremia.

One hundred and twenty-two members of 15 choroideremia families have been used in a genetic linkage study of choroideremia (TCD) using four DNA probes situated on the X chromosome. Linkage was analysed using DNA probes DXS14 (p58-1), DXYS1 (pDP 34), DXS178 (p212) and DXS177 (lambda 2.7). Statistically significant linkage was demonstrated with DXYS1 (theta = 0.00, lod 4.95), in agreement with the findings of Nussbaum et al. (1985). Evidence consistent with loose linkage to TCD was also found with DXS14 (theta = 0.31, lod 0.23), DXS178 (theta = 0.18, lod 1.41) and DXS177 (theta = 0.27, lod 0.20). The results suggest that TCD is located in the region Xq13-q21. Probe DXYS1 is likely to prove useful in the prenatal diagnosis of this condition.