Figure 4.

Recombination Events on hap.01 HD Chromosomes

(A) RefSeq genes are indicated in blue arrows above the orange traces, which represent the HapMap recombination rates (chr4: 2,500,000–4,000,000 bp region). Recombination rates are very low around HTT, and recombination peaks are located centromerically. The red arrow indicates the highest recombination peak in this region, where two recombination events were detected.

(B) In an expanded view of the highest recombination peak, the reference genomic coordinates with recombination rates are aligned with actual recombination events in (C) and (D). Both recombination events were located within the recombination peak at chr4: 3,725,000 bp.

(C) A recombination event in family 1 is shown. Five transmitted HD chromosomes were compared for chr4: 22,500,000–4,000,000, revealing a recombination event in the maternal transmission in trio 2. The mother’s disease chromosome (red) and normal chromosome (green) are compared to the transmitted disease chromosomes (red and green). Only bases at sites of heterozygosity are shown.

(D) A similar analysis to that in (C) was performed for family 4. One recombination event was detected in the paternal transmission of trio 4.