For example, NG381 (idiopathic nystagmus with incomplete phenotyping) was found to be homozygous for an assumed likely pathogenic splicing variant in the CACNA1F gene, which is known to cause Aland Island eye disease, cone-rod dystrophy and X-linked incomplete stationary night blindness (CSNB); all of which cause nystagmus and retinal dystrophy. Here, CACNA1F is linked to Aland island eye disease.