The major finding in this Chinese family with familial aniridia is the presence of a 566 kb heterozygous deletion containing four annotated genes: DCDC1, DNAJC24, IMMP1L, and ELP4. The proximal breakpoint of this deletion is approximately 123 kb from the 3′ end of PAX6. We postulate that this 566 kb heterozygous deletion is the underlying cause of the familial aniridia and acts by disrupting the transcription in one of the two PAX6 alleles, even though the two copies of PAX6 were intact in all individuals investigated in this study. This evidence concerns the gene IMMP1L and isolated aniridia.