A severe form of the tetrasomy 18p syndrome confirmed by in situ hybridization

Tetrasomy 18p is a rare disorder due to a supernumerary metacentric small c hromosome identified as an isochromosome 18p. Setting of cytogenetic molecu lar techniques has permitted to confirm this syndrome in many cases; in fac t today is thought that this syndrome has a distinct phenotype. We report a new case of tetrasomy 18p syndrome confirmed by in situ hybridization, cha racterized from severe clinical features and from the presence of megaepigl ottis, never reported in other patients.