PALB2 and hypoparathyroidism-retardation-dysmorphism syndrome: Tumor suppressor genes implicated in homologous recombination repair deficiency (HRD) were a recurrent feature of the cohort, including ATM (n = 4), BRCA1 (n = 4), BRCA2 (n = 2), CHEK2 (n = 2), and PALB2 (n = 1) (Table 2).