Sibswithtetrasomy 18pborntoamotherwithtrisomy 18p

8p) de novo.Theolder sister hasmicrocephaly, mentalretardation, anasymmetrical andpeculiar facewithlowsetears, pinched upnose, high archedpalate, smallmouth,micrognathia, tapering fingers, asymmetrical length oflegs, andanasthenic body. Theyounger sister was stillborn withextensive defects oftheskull, congenital hydrocephalus, severefacial anomalies, and lumbosacral meningocele. Bothdaughters haveinherited onenormal chromosome 18andanisochromosome 18p fromtheir mother, andonenormalchromosome18fromtheir father. Although onequite similar family hasbeenreported, tothebest of ourknowledge there havebeennoreports of families inwhich twodaughters withtetrasomy 18psyndrome havebeenborntoamother with trisomy 18pwithisochromosomes. Basedonacomparative analysis of18cases, Rivera etallconcluded thattetrasomy 18pconstitutes a clinically andcytoenetically recognisable syndrome.Frynsetalgavefurther support tothe existence ofsucha clinical entity. We present a family inwhichtwodaughters withtetrasomy 18p wereborntoamotherwithdenovotrisomy 18p.