Heterozygous germline SMCHD1 mutations have been reported in at least three distinct rare human genetic diseases, type 2 facioscapulohumeral muscular dystrophy (FSHD2, OMIM #158901) (20–22), Bosma arhinia and microphtalmia syndrome (BAMS, OMIM #603457) (23,24) and isolated hypogonadotrophic hypogonadism with combined pituitary hormone deficiency and septo-optic dysplasia (25). This evidence concerns the gene SMCHD1 and hereditary disease.