ALPL and hypophosphatasia: Genetic counseling of hypophosphatasia is complicated by the inheritance that may be autosomal dominant or autosomal recessive, the existence of the uncommon prenatal benign form [4,5], the variable expression of the disease in heterozygotes, the probable effect of ALPL gene polymorphisms, and the possible effect of mutations and polymorphisms of other genes that may modulate the hypophosphatasia phenotype (modifier genes).