It has long been postulated that germline mosaicism in healthy parents could be the most likely explanation for the exceptional disease recurrence in affected siblings with no family history of aniridia (Reed and Falls, 1955; Gronskov et al., 1999) or PAX6-related microphthalmia (Deml et al., 2016; Riera et al., 2017). This evidence concerns the gene PAX6 and microphthalmia.