CACNB4 and Ataxia: Our gene expression co-variation network (Fig. 5) indicates that this gene co-varies with the Chr 1 positional candidate Dcaf8, as well as the Chr 2 candidates Arl6ip6 and Galnt13. Cacnb4 has been identified as the gene responsible for the lethargic (lh) mouse phenotype, which includes ataxia and absence epilepsy [89].