Partial monosomy 22pter leads to q11 in a newborn with the clinical features of trisomy 13 syndrome.

In a female newborn with the clinical and postmortem findings of Pätau's syndrome no trisomy 13 could be found by chromosomal investigation. Rather, the karyotype 45,XX,-11,-22,+(11;22) (p15;q11) was ascertained by GTG-,RFA-and TFA-banding. The long arm of one chromosome 22 is translocated upon the short arm of one chromosome 11, and the remaining part of the derivative chromosome 22 is lost. The child therefore is monosomic for 22pter leads to q11 and probably for the telomeric region of 11p15. Since both parents possess normal karyotypes, it is a de novo translocation. The case in point illustrates that the more correlation of a given phenotype to a specific karyotype is not possible in all cases.