The Sar1B GTPase is an enzyme located in epithelial cells of the gastrointestinal tract. These proteins are critical for release of<unk> s in the body.<unk>  is an autosomal homozygous recessive disorder arising from mutations in the gene encoding the Sar1B GTPase. The Sar1B gene is located at position 5q31.1 in the fifth chromosome and is composed of eight exons. Alternative splicing of the second exon results into two different splice isoforms for the Sar1B transcript RNA. In CMRD, a mutation of this genomic sequence affects the Sar1B enzyme's ability to interact with Guanine Exchange Factors (GEFs) and GTP-Activating Proteins (GAPs). The mutation of exon 6 of the sequence can eliminate the critical chain that is responsible for recognizing guanine. This strips the GTPase of its capability to hydrolyze GTP, its hallmark trait. This overall affects the ability of Sar1B GTPase to control<unk>  release. A third mutant allele containing a missense mutation has also been reported to cause CMRD. All three of these alleles display recessive inheritance, suggesting that they loss-of-function mutations cause the symptoms of CMRD.
Chylomicron retention disease
Lysinuric protein intolerance
Inborn errors of carbohydrate metabolism
Acid lipase disease
Hereditary fructose intolerance
Glucose-galactose malabsorption
Glycogen storage disease type 0
Congenital chloride diarrhea