Thus, while heterozygous CRKL, SCARF2, or PI4KA deletion may not be necessary for core 22q11DS phenotypes, diminished dosage of one or more of these genes in individuals with the A to D deletion may enhance heart, face, or brain phenotypes, yielding more severe impairments or introducing greater phenotypic variation. This evidence concerns the gene CRKL and 22q11.2 deletion syndrome.