title: Coexistent mosaic monosomy 21 and fragile X syndrome in a mentally retarded male patient.
abstract: Fragile X syndrome (FXS) is a well-recognized mental retardation syndrome with characteristic facial features and behavioural phenotype. Monosomy 21 is a rare cytogenetic aberration for which clinical features were incompletely defined since full monosomy 21 is incompatible with life. A 5-year-old male patient with FXS and low-grade mosaicism for full monosomy 21 (46,XY[96%]/45,XY,-21[4%]) is presented. He had lack of speech and severely impaired social skills, hyperactivity, stereotypical hand movements, a special interest towards moving colourful items and a short attention span for other objects around. He had macrocephaly, a rather long face, prominent occiput and prominent midface, retrognathia, down-slanting palpebral fissures, hypertelorism and cup-shaped, posteriorly rotated and low-set ears. Full monosomy in the aberrant cell line was proven by whole chromosome painting. FXS was previously reported to accompany sex chromosome aneuploidies; however, to the best of our knowledge, the present patient is the first FXS patient with an aberration involving autosomes. He contributes to the current knowledge on monosomy 21 phenotype, having dysmorphic facial findings despite the concurrent phenotypic expression of the FXS. As a last conclusion, cytogenetic analysis must be done to all mentally retarded patients with minor dysmorphic features.
authors: Hacettepe University Faculty of Medicine, Department of Pediatrics, Division of Genetics, 06100 Sihhiye, Ankara, Turkiye. geutine@hacettepe.edu.tr
authors: G E
authors: GE
authors: Utine
authors: D
authors: D
authors: Aktas
authors: K
authors: K
authors: Boduroğlu
authors: M
authors: M
authors: Alikasifoğlu
authors: E
authors: E
authors: Tunçbilek
mesh_terms: D002675:Child, Preschool; D002869:Chromosome Aberrations; D020223:Chromosome Painting; D002891:Chromosomes, Human, Pair 21 / Q000235:genetics*; D015897:Comorbidity; D019465:Craniofacial Abnormalities / Q000175:diagnosis / Q000235:genetics*; D019066:Facies; D005600:Fragile X Syndrome / Q000175:diagnosis / Q000235:genetics*; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D008607:Intellectual Disability / Q000175:diagnosis / Q000235:genetics*; D008297:Male; D009006:Monosomy / Q000235:genetics*; D009030:Mosaicism; D010641:Phenotype