- A third MRX family (MRX68) is the result of mutation in the long chain fatty acid-CoA ligase 4 (FACL4) gene: proposal of a rapid enzymatic assay for screening mentally retarded patients. Longo, I., Frints, S.G., Fryns, J.P., Meloni, I., Pescucci, C., Ariani, F., Borghgraef, M., Raynaud, M., Marynen, P., Schwartz, C., Renieri, A., Froyen, G. J. Med. Genet. (2003)









