Lesch-Nyhan syndrome (OMIM phenotype number 300322) is an XLR condition due to an inactivating variant in HPRT1, resulting in hyperuricemia with subsequent intellectual disability, involuntary movements, self-injurious behavior, gout, and uric acid NL (Madeo et al., 2019). The gene discussed is HPRT1; the disease is Lesch-Nyhan syndrome.