POMGNT1 and retinitis pigmentosa 76: Interestingly, hypomorphic mutations in one of the enzymes required for matriglycan synthesis called protein O-mannose N-acetylglucosaminyltransferase 1 (POMGnT1) are found in several cases of non-syndromic retinitis pigmentosa (RP76, OMIM#617123) [30,31].