Occasionally, childhood‐onset cancer may occur in individuals with biallelic GPVs in conditions where adult‐onset cancers are characteristic in individuals heterozygous for the GPV, as with BRCA2 (causing Fanconi anaemia, FANCD1 in biallelic GPV carriers), although homozygous GPVs in such genes (particularly if truncating, or complete loss‐of‐function) may result in embryonic lethality (Rahman and Scott 2007). Here, BRCA2 is linked to Fanconi anemia.