Heterozygous carriers of the disrupted Cyp7a1 gene are phenotypically normal, viable, and fertile. Homozygous animals appear normal at birth but most die within the first 18 days of life. The 10-15% of homozygotes that survive are fertile. Newborn animals with a homozygous mutation in the Cyp7a1 gene lack bile acids, causing fat malabsorption as manifest by severe steatorrhea (fatty stools), deficiency of fat-soluble vitamins, and wasting due to malnutrition. Approximately 40% of the homozygotes die between postnatal days 1-4; 45% between days 11-18. Vitamin supplements given to nursing mothers can prevent deaths during the early period; cholic acid supplements in the mother's diet can prevent deaths in the later period. Mutant pups born to homozygous mothers not maintained on dietary supplements are noticeably smaller than age-matched heterozygous and wild type siblings. The skin of nursing homozygotes can be dry and scaly in appearance. Nursing heterozygous and homozygous mothers and their mutant pups not treated with cholic acid develop an unusually oily coat. No immunoreactive or enzymatically active Cyp7a1 proteins are produced in homozygous mutants, but a novel "hybrid" mRNA present in heterozygous and homozygous animals is composed of sequences derived from the 5' and 3' ends of the mutated gene.

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These Cyp7a1 knock-out mice exhibit wasting and early mortality with a lack of bile acids, and may be of use in applications related to the study of fat and vitamin malabsorption.

Typically mice are recovered in 12-16 weeks. Contact Customer Service to place an order or for more information.

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