ClinVar

Berkovic et al. (2008) identified an SCARB2 mutation in 1 of the original families with action myoclonus with renal failure (EPM4; 254900) from Quebec reported by Badhwar et al. (2004). The 3 affected members were deceased, and no DNA was available for testing, but obligate carriers of this disorder had the mutation in exon 7 862C-T (gln288ter, Q288X), which was predicted to terminate the protein prematurely or lead to nonsense-mediated RNA decay of the transcript.

In a patient with progressive myoclonic epilepsy without renal failure, Dibbens et al. (2011) identified compound heterozygosity for 2 mutations in the SCARB2 gene: Q288X and a 1-bp insertion in intron 9 (1187+3insT; 602257.0007). The patient was originally reported by Costello et al. (2009). He had onset of myoclonic epilepsy at age 16 years, and became severely disabled, requiring a wheelchair by age 20. At age 27, he had intractable myoclonus, dysarthria, and dysphagia, but cognition remained intact and there was no evidence of renal failure. Electrophysiologic studies indicated a demyelinating peripheral neuropathy, with reduced sensory and motor action potentials and mildly decreased nerve conduction velocities.