title: A rare case of trisomy 15pter-q21.2 due to a de novo marker chromosome.
abstract: Supernumerary marker chromosomes (sSMC) may or may not be associated with an abnormal phenotype, depending on the presence of euchromatin, on their chromosomal origin and whether they are inherited. Over 80% of sSMCs are derived from acrocentric chromosomes and half of them include the short arm of chromosome 15. Generally, they appear as bisatellited isodicentric marker chromosomes, most of them are symmetric. These chromosomes are normally originated de novo and are associated with mild to severe intellectual disability but not with physical abnormalities. We report on a patient with an SMC studied using classical and molecular cytogenetic procedures (G and C banding, NOR staining, painting and centromeric fluorescent in situ hybridization (FISH), BAC-FISH, and SKY). The MLPA technique and DNA polymorphic markers were used in order to identify its parental origin. The marker chromosome, monosatellited and monocentric, was found to be derived from a maternal chromosome 15 and was defined as 15pter-q21.2. This is the report of the largest de novo monosatellited 15q marker chromosome ever published presenting detailed cytogenetic and clinical data. It was associated with a phenotype including cardiac defect, absence of septum pellucidum, and dysplasia of the corpus callosum.
authors.affiliation: Department of Morphology and Genetics, Universidade Federal de São Paulo, São Paulo, Brazil.
authors.forename: Ade Nubia Xavier
authors.initials: AN
authors.lastname: Pacanaro
authors.forename: Denise Maria
authors.initials: DM
authors.lastname: Christofolini
authors.forename: Leslie Domenici
authors.initials: LD
authors.lastname: Kulikowski
authors.forename: Sintia Iole Nogueira
authors.initials: SI
authors.lastname: Belangero
authors.forename: Fernanda Teixeira
authors.initials: FT
authors.lastname: da Silva Bellucco
authors.forename: Monica C
authors.initials: MC
authors.lastname: Varela
authors.forename: Celia P
authors.initials: CP
authors.lastname: Koiffmann
authors.forename: Maisa
authors.initials: M
authors.lastname: Yoshimoto
authors.forename: Jeremy A
authors.initials: JA
authors.lastname: Squire
authors.forename: Adriana V
authors.initials: AV
authors.lastname: Schiavon
authors.forename: Benjamin
authors.initials: B
authors.lastname: Heck
authors.forename: Maria Isabel
authors.initials: MI
authors.lastname: Melaragno
mesh_terms: D000015:Abnormalities, Multiple / Q000235:genetics*; D055673:Acrocallosal Syndrome / Q000235:genetics; D002884:Chromosomes, Human, Pair 15 / Q000235:genetics*; D002658:Developmental Disabilities / Q000235:genetics; D005260:Female; D005819:Genetic Markers; D006330:Heart Defects, Congenital / Q000235:genetics; D006801:Humans; D007223:Infant; D010641:Phenotype; D012688:Septum Pellucidum / Q000002:abnormalities; D032681:Spectral Karyotyping; D014314:Trisomy
chemical_list: D005819:Genetic Markers