A reasonably straightforward genotype-phenotype correlation of the disease has been suggested: early reports indicate frameshift, nonsense, and splice site mutations resulting in an absent CHS1/LYST protein correlate with severe childhood CHS, whereas milder adolescent or adult forms of CHS present with at least one missense mutation probably encoding a partially functioning protein [5,34,39]. The gene discussed is LYST; the disease is Chédiak-Higashi syndrome.