ACROMESOMELIC DYSPLASIA MAROTEAUX TYPE MAPS TO HUMAN-CHROMOSOME-9

Acromesomelic dysplasias are skeletal disorders that disproportionatel y affect the middle and distal segments of the appendicular skeleton. We report genetic mapping studies in four families with acromesomelic dysplasia Maroteaux type (AMDM), an autosomal recessive osteochondrody splasia. A peak LOD score of 5.1 at recombination fraction 0 was obtai ned with fury informative markers on human chromosome 9. In three of t he four families, the affected offspring are products of consanguineou s marriages; if it is assumed that these affected offspring are homozy gous by descent for the region containing the AMDM locus, a 6.9-cM AMD M candidate interval can be defined by markers D9S1853 and D9S1874. Th e mapping of the AMDM locus to human chromosome 9 indicates that AMDM is genetically distinct from the two other mapped acromesomelic dyspla sias, Hunter-Thompson type and Grebe type, which are caused by mutatio ns in CDMP1 on human chromosome 20.