A novel growth retardation and abnormal gonad morphology locus on mouse chromosome 4.

Mutant mice exhibiting a growth retardation phenotype arose spontaneously in the inbred NC/Sgn mouse strain. The mode of inheritance of this mutation was autosomal recessive, and I named this mutation growth deficit (gd). The gd locus was mapped to the proximal part of chromosome 4, between microsatellite markers D4Mit139 and D4Mit178. Histologic abnormalities were detected in the mutant testis and ovary. Degeneration and/or necrosis were found in the seminiferous epithelium, particularly in the spermatocytes; therefore, mutant males were thought to be sterile owing to defective spermatogenesis. Mutant ovaries were generally atrophied. Necrosis of granulosa cells and increased number of atretic follicles were remarkable. The gd locus is suggested to be syntenic to human chromosome segment 9q32-q34, to which no similar mutations had been mapped. Although the molecular nature of this mutation is unclear, gd promises to make future contribution to relevant diseases in human beings.