Syndromic Disorders Caused by Disturbed Human Imprinting

Imprinting disorders are a group of congenital diseases caused by dysregulation of genomic imprinting and affecting prenatal and postnatal growth, neurocognitive development, metabolism and cancer predisposition. Aberrant expression of imprinted genes can be achieved through different mechanisms, classified into epigenetic --- if not involving DNA sequence change --- or genetic --- in case of altered genomic sequence. Despite the underlying mechanism, the phenotype depends on the parental allele affected and opposite phenotypes may result in case of involvement of the maternal or the paternal chromosome. Imprinting disorders are largely underdiagnosed because of the broad range of clinical signs, the presentation overlap among different disorders, the presence of mild phenotypes, the mitigation of the phenotype with age and the limited availability of the molecular techniques employed for the diagnosis. This review briefly illustrates the currently known human imprinting disorders highlighting endocrinological aspects of pediatric interest.