title: Duplication 9p and their implication to phenotype.
abstract: BACKGROUND
  Trisomy 9p is one of the most common partial trisomies found in newborns. We report the clinical features and cytogenomic findings in five patients with different chromosome rearrangements resulting in complete 9p duplication, three of them involving 9p centromere alterations.
  
  
  METHODS
  The rearrangements in the patients were characterized by G-banding, SNP-array and fluorescent in situ hybridization (FISH) with different probes.
  
  
  RESULTS
  Two patients presented de novo dicentric chromosomes: der(9;15)t(9;15)(p11.2;p13) and der(9;21)t(9;21)(p13.1;p13.1). One patient presented two concomitant rearranged chromosomes: a der(12)t(9;12)(q21.13;p13.33) and an psu i(9)(p10) which showed FISH centromeric signal smaller than in the normal chromosome 9. Besides the duplication 9p24.3p13.1, array revealed a 7.3 Mb deletion in 9q13q21.13 in this patient. The break in the psu i(9)(p10) probably occurred in the centromere resulting in a smaller centromere and with part of the 9q translocated to the distal 12p with the deletion 9q occurring during this rearrangement. Two patients, brother and sister, present 9p duplication concomitant to 18p deletion due to an inherited der(18)t(9;18)(p11.2;p11.31)mat.
  
  
  CONCLUSIONS
  The patients with trisomy 9p present a well-recognizable phenotype due to facial appearance, although the genotype-phenotype correlation can be difficult due to concomitant partial monosomy of other chromosomes. The chromosome 9 is rich in segmental duplication, especially in pericentromeric region, with high degree of sequence identity to sequences in 15p, 18p and 21p, chromosomes involved in our rearrangements. Thus, we suggest that chromosome 9 is prone to illegitimate recombination, either intrachromosomal or interchromosomal, which predisposes it to rearrangements, frequently involving pericentromeric regions.
authors.affiliation: Department of Morphology and Genetics, Universidade Federal de São Paulo, Rua Botucatu 740, CEP, 04023-900, São Paulo, Brazil. robertaguilherme@hotmail.com.
authors.forename: Roberta Santos
authors.initials: RS
authors.lastname: Guilherme
authors.affiliation: Department of Morphology and Genetics, Universidade Federal de São Paulo, Rua Botucatu 740, CEP, 04023-900, São Paulo, Brazil. vera.meloni@gmail.com.
authors.forename: Vera Ayres
authors.initials: VA
authors.lastname: Meloni
authors.affiliation: Department of Morphology and Genetics, Universidade Federal de São Paulo, Rua Botucatu 740, CEP, 04023-900, São Paulo, Brazil. bialvarez@uol.com.br.
authors.forename: Ana Beatriz Alvarez
authors.initials: AB
authors.lastname: Perez
authors.affiliation: Department of Morphology and Genetics, Universidade Federal de São Paulo, Rua Botucatu 740, CEP, 04023-900, São Paulo, Brazil. anapilla@uol.com.br.
authors.forename: Ana Luiza
authors.initials: AL
authors.lastname: Pilla
authors.affiliation: Department of Morphology and Genetics, Universidade Federal de São Paulo, Rua Botucatu 740, CEP, 04023-900, São Paulo, Brazil. annamarco@uol.com.br.
authors.forename: Marco Antonio Paula
authors.initials: MA
authors.lastname: de Ramos
authors.affiliation: Department of Morphology and Genetics, Universidade Federal de São Paulo, Rua Botucatu 740, CEP, 04023-900, São Paulo, Brazil. anegdantas@hotmail.com.
authors.forename: Anelisa Gollo
authors.initials: AG
authors.lastname: Dantas
authors.affiliation: Department of Morphology and Genetics, Universidade Federal de São Paulo, Rua Botucatu 740, CEP, 04023-900, São Paulo, Brazil. sylvinha66@yahoo.com.br.
authors.forename: Sylvia Satomi
authors.initials: SS
authors.lastname: Takeno
authors.affiliation: Department of Pathology, Laboratório de Citogenômica, Universidade de São Paulo, Avenida Dr. Eneas Carvalho de Aguiar 647, CEP, 05403-000, São Paulo, Brazil. lesliekulik@gmail.com.
authors.forename: Leslie Domenici
authors.initials: LD
authors.lastname: Kulikowski
authors.affiliation: Department of Morphology and Genetics, Universidade Federal de São Paulo, Rua Botucatu 740, CEP, 04023-900, São Paulo, Brazil. melaragno.maria@unifesp.br.
authors.forename: Maria Isabel
authors.initials: MI
authors.lastname: Melaragno
mesh_terms: D000293:Adolescent; D002648:Child; D002899:Chromosomes, Human, Pair 9 / Q000235:genetics; D005260:Female; D056726:Genetic Association Studies; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D008297:Male; D020411:Oligonucleotide Array Sequence Analysis; D010641:Phenotype; D011995:Recombination, Genetic; D014178:Translocation, Genetic; D014314:Trisomy / Q000235:genetics*