7 LOCI ON HUMAN-CHROMOSOME-4 MAP ONTO SHEEP CHROMOSOME-6 - A PROPOSALTO RESTORE THE ORIGINAL NOMENCLATURE OF THIS SHEEP CHROMOSOME

Seven new loci, casein alpha-S1 (CSN1S1), casein alpha-S2 (CSN1S2), ca sein beta (CSN2), the Hardy-Zuckerman 4 feline sarcoma viral (v-kit) o ncogene homolog (KIT), albumin (ALB), phosphodiesterase cyclic GMP (ro d receptor) beta polypeptide (PDEB), and complement component 1 (IF), were assigned to sheep Chromosome (Chr) 6 by Southern hybridization to a panel of chromosomally characterized sheep X hamster cell hybrids. By isotopic in situ hybridization, CSN2 was regionally localized to sh eep Chr (OOV) 6q22-q31, anchoring this syntenic group of markers on to OOV6 and confirming its homology at a molecular and cytological level with cattle Chr 6. The assignment of these loci, from PDEB (located o n human Chr 4p16.3) to IF (on HSA4q24-q25), and the observation that i nterleukin 2 (IL2, on HSA4q26q27) and tryptophan 2,3-dioxygenase (TDO2 , on HSA4q31) are not located on OOV6, is further evidence of the clos e evolutionary relationship of sheep and cattle and the conserved synt eny in these species of this extensive region of human Chr 4. On the b asis of this conserved synteny, and the similar G- and Q- banding patt erns of this chromosome in cattle and sheep, we propose that this shee p chromosome be numbered as 6, not 4 as recommended by ISCNDA (1990).