Genetic mapping of hereditary motor and sensory neuropathy type Russe (HMSN-R): findings in the region of linkage on chromosome 10q23 This affected family originates from a closed endogamous Romani group where consanguineous marriages are common. The linkage study was conducted using the ABI Prism Linkage Mapping Sets LMS and LMS version 2 (PE Biosystems), with an average intermarker distance of 10 cM. The ABI panel markers flanking the HMSN-R region (shown in blue) presented with different alleles in the affected individuals. Haplotype heterozygosity, resulting from historical recombinations and a recent cross-over event (individual R-11), extended into the 10 cM interval containing the gene and could have resulted in exclusion of the region if homozygosity mapping had been used. In the set of affected families included in the original study , the conserved region of homozygosity (red bars) was found to span only <500 kb. Courtesy of Dr. Tamara Rogers.