Moreover, homologous recombination repair deficiency (HRD), caused by loss of BRCA1 or BRCA2 function, leaves a specific genomic imprint on the DNA characterized by two single base substitution (SBS) signatures (SBS3 and SBS8), one small insertion/deletion (ID) signature (ID6) and two specific structural variant (SV) signatures (SV3 for BRCA1-type cancers and SV5 for BRCA2-type cancers) [22–24]. This evidence concerns the gene BRCA1 and hypoparathyroidism-retardation-dysmorphism syndrome.