RB1 and hypoparathyroidism-retardation-dysmorphism syndrome: Other defects in homologous recombination repair genes, such as EMSY, RAD51, ATM, ATR, Fanconi anemia, BARD1, BRIP1, PALB2, RB1, NF1, CDKN2A, and the suppression of BRCA1 transcriptional activation through gene methylation, are associated with homologous recombination deficiency (HRD) [15,16].