title: Characterization of a de novo Supernumerary Neocentric Ring Chromosome Derived from Chromosome 7.
abstract: Supernumerary ring chromosomes (SRC) are usually derived from regions adjacent to the centromere. Their identification may be challenging, particularly in case of low mosaicism. Here, we report on a patient who was referred for major in utero growth retardation, severe developmental delay, facial dysmorphism, cleft palate, and hypospadias. The karyotype showed a small SRC in mosaic. The combination of FISH, M-FISH and array-CGH was necessary for a complete characterization of this SRC. M-FISH revealed that the SRC originated from chromosome 7. Array-CGH performed with a 400K oligonucleotide array showed a gain in region 7q22.1q31.1 present in low mosaic. This result was confirmed by FISH using BAC probes specific for chromosome 7. The SRC was a neocentric ring derived from 7q22.1q31.1 and was found in only 8% of the cells. This is the first patient carrying a mosaic neocentric SRC derived from the long arm of chromosome 7. Our study emphasizes the need to combine different techniques and to use adapted bioinformatic tools for low-mosaicism marker identification. It also contributes to the delineation of the partial trisomy 7q phenotype.
authors.affiliation: Laboratoire de Cytogx00E9;nx00E9;tique Constitutionnelle, Service de Gx00E9;nx00E9;tique, Centre de Biologie et de Pathologie Est, Bron, France.
authors.forename: Camille
authors.initials: C
authors.lastname: Louvrier
authors.forename: Grégory
authors.initials: G
authors.lastname: Egea
authors.forename: Audrey
authors.initials: A
authors.lastname: Labalme
authors.forename: Vincent
authors.initials: V
authors.lastname: Des Portes
authors.forename: Sophie
authors.initials: S
authors.lastname: Gazzo
authors.forename: Evelyne
authors.initials: E
authors.lastname: Callet-Bauchu
authors.forename: Marianne
authors.initials: M
authors.lastname: Till
authors.forename: Damien
authors.initials: D
authors.lastname: Sanlaville
authors.forename: Patrick
authors.initials: P
authors.lastname: Edery
authors.forename: Caroline
authors.initials: C
authors.lastname: Schluth-Bolard
mesh_terms: D000015:Abnormalities, Multiple / Q000235:genetics*; D002503:Centromere / Q000235:genetics; D002648:Child; D002675:Child, Preschool; D002871:Chromosome Banding; D002897:Chromosomes, Human, Pair 7 / Q000235:genetics*; D055028:Comparative Genomic Hybridization; D002658:Developmental Disabilities; D005145:Face / Q000002:abnormalities; D005317:Fetal Growth Retardation; D005500:Follow-Up Studies; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D007223:Infant; D007231:Infant, Newborn; D007621:Karyotyping; D008297:Male; D009030:Mosaicism; D012303:Ring Chromosomes