For GS and all BS subtypes the mode of inheritance is monogenic autosomal recessive except those associated with mitochondrial DNA mutations; BS type 4B, which is digenic recessive; BS type 5, which is X-linked recessive; and BS with ADH, or GS-like with FXYD2 or HNF1B, which are autosomal dominant [4, 5, 17]. Here, HNF1B is linked to Bloom syndrome.