Author(s):
Pires, Sílvia 
; Fonseca Silva, Maria da Luz ; Rosa Pereira, Ana ; Meireles, Alexandra ; Oliva Teles, Natália ; Ribeiro, Joana ; Mota Freitas, Manuela ; Marques, Bárbara ; Soares, Gabriela ; Brandão, Otilia ; Correia, Hildeberto
Date: 2011
Persistent ID: http://hdl.handle.net/10400.18/631
Origin: Repositório Científico do Instituto Nacional de Saúde
Subject(s): Doenças Genéticas; Prenatal Diagnosis; Dup(16p); Recombinant Chromosome
Description
Poster: 10.P7 Chromosomal rearrangements involving three break-points are relatively rare, about 1/5,000 live births. When a chromosomal segment is moved from one part of a chromosome into another part of the same chromosome, it is considered an intrachromosomal insertion; the orientation of the inserted material in relation to the centromere may remain the same, resulting in a direct insertion, or reversed, resulting in an inverted insertion. A single crossover in the gametogenesis between any of the three breakpoints may result in unbalanced recombinants, leading to phenotypic consequences in the offspring.
Partial trisomy 16p is a rare chromosomal imbalance characterized by mental retardation, prenatal and post-natal growth deficiency, facial anomalies, cleft palate, congenital heart defects, and urogenital anomalies.
Previous studies have established that the phenotype of this condition is not related to the extension of the duplicated segment and that the region 16p13.1–p13.3 is critical in determining this disorder.
We report on a prenatal diagnosis performed at 14 weeks. The fetus presented with an increased fetal nuchal translucency and thus was referred for con- ventional cytogenetic studies.
The chromosomal analysis of the amniotic fluid cells revealed a structurally abnormal chromosome 16, with additional material on 16q. The maternal karyotype was normal, but the father carried an intrachromosomal insertion in chromosome 16: a between-arm insertion of a small segment of the short arm into the distal region of the long arm. To characterize the extension of the imbalance in the fetus, chromosome comparative genomic hybridization (cCGH) analysis was performed. Fetus karyotype: 46,XY,rec(16)dup(16p)ins(16) (q24p13.2p13.3)pat.ish cgh dup(16)(p13.2p13.3).
The authors emphasize the rarity of this case, explain its possible formation mechanism and compare the fetal phenotype (available after autopsy) with similar cases described in the literature
