Sar: A genetic mouse model for human sarcosinemia generated by ethylnitrosourea mutagenesis

A mouse mutant with sarcosinemia was found by screening the progeny of ethylnitrosourea-mutagenized mice for aminoacidurias. Paper chromatography, column chromatography, and gas chromatography-mass spectrometry identified high levels of sarcosine in the urine of the mutant mice. While sarcosine cannot be detected in the urine or plasma of normal mice, the urinary sarcosine level of 102 ± 58 mmol per g of creatinine in the mutant mice was at the upper range of the urinary levels (1.5-45 mmol of sarcosine per g of creatinine) observed in humans with sarcosinemia. Similarly, the plasma sarcosine level of 785 ± 153 μmol/liter in the sarcosinemic mice was at the upper range of the plasma sarcosine levels (53-760 μmol/liter) observed in affected humans. Sarcosine dehydrogenase [sarcosine: (acceptor) oxidoreductase (demethylating), EC 1.5.99.1] activity was deficient in sarcosinemic mice. The sarcosinuria phenotype in these mice was inherited as an autosomal recessive trait. This mouse mutant provides a useful genetic model for human sarcosinemia and for development of therapeutic approaches for genetic disease.