Trisomy 8 mosaicism in a patient born to a mother with 47,XXX.

We report an unusual case of mosaic trisomy 8 in a girl born to a mother with karyotype 47,XXX. The patient showed most of the characteristics of this syndrome as : round face, hypertelorism, large ears, micrognathia, clinodactyly, camptodactyly, deep palmar and plantar creases, cryptorchidism, hydronephrosis, cardivascular anomalies, agenesis of the corpus callosum and mental retardation.Chromosome analysis using standard cytogenetic protocols and FISH ( fluorescent in situ hybridization ) showed a mos,47,XX+8/46,XX karyotype ( 80% of examined metaphases trisomic for 8 chromosome, 20% with normal karyotype ).The phenotype in trisomy 8 mosaicism syndrome can be highly variable. Two hypotheses could explain this variability; first , tissue specific mosaicism may play a role ; second , some individuals with trisomy 8 mosaicism may have derived it from a trisomic zygote. In these individuals the normal cell line would be a product of chromosomal loss. Therefore,uniparental disomy could be a factor in phenotypic variability.Concerning the mechanism of formation,the common autosomal trisomy are due to errors in maternal meiosis in majority of the cases.In trisomy 8 nondisjunction would probably due to mitotic ( postziotic ) duplication. The co-occurence of 47,XXX in the mother and trisomy 8 in child could be only by chance.