Faculty Research 1980 - 1989


Mouse serum amyloid P-component (SAP) levels controlled by a locus on chromosome 1.

Document Type


Publication Date



Animal, Chromosome-Mapping, Gene-Expression-Regulation, Linkage-(Genetics), Mice: bl, ge, SUPPORT-U-S-GOVT-P-H-S

JAX Source

Immunogenetics. 1985; 22(4):367-75.


CA30015, GM18684, CA33093


Recombinant inbred strains were used to demonstrate the existence of a major locus on chromosome 1, designated Sap, which controls the endogenous concentration of the mouse acute phase reactant, serum amyloid P-component (SAP). Levels of SAP were associated with alleles at the Ly-9 locus in two sets of RI strains: BXD (C57BL/6J X DBA/2) and BXH (C57BL/6J X C3H/HeJ). Low endogenous levels of SAP were present in the C57BL/6J progenitor strain and in most of the RI strains which inherited the Ly-9b allele. High levels of SAP were present in the DBA/2J and C3H/HeJ progenitors and in most of the RI strains which inherited the Ly-9a allele. In the BXD strains 91% of the genetic variation of SAP levels was accounted for by segregation at the Ly-9 locus while an additional 9% was attributed to genetic factors unlinked to Ly-9. In the BXH strains the percentage of genetic variation accounted for by Ly-9 segregation was reduced to 46%, while 54% was accounted for by other genetic factors. Because of background genetic variation it was not possible to detect any crossovers between Sap and Ly-9. However, in the BXD strains the linkage between Sap and Ly-9 appears to be quite close. The B6.C-H-25c congenic strain, which carries a segment of BALB/c chromosome 1 including the minor histocompatibility locus H-25 on a C57BL/6By background, had the same endogenous SAP level as the BALB/c donor strain.

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