Cytogenetic, Molecular, and Phenotypic Characterization of a Patient with de novo Derivative Chromosome 18 and Review of the Literature

We present a patient with a de novo derivative chromosome 18 which includes a terminal deletion of 18p and a terminal duplication of 18q accompanied by a cryptic duplication of 18p. The girl had mild dysmorphic features such as micro-retrognathia, upslanted palpebral fissures, bilateral epicanthus, high palate, low-set ears, short neck, and full cheeks. She also had an H-type tracheoesophageal fistula which required surgery. Her cognitive and motor skills were delayed. Karyotype analysis showed an additional segment on the short arm of chromosome 18. Chromosomal microarray revealed a 7.3-Mb terminal loss from 18p11.32 to 18p11.23, a 22.2-Mb terminal gain from 18q21.31 to 18q23, and a 3.9-Mb interstitial gain from 18p11.22 to 18p11.21. We hypothesize that the mother has gonadal mosaicism for normal chromosome 18, der(18)dup(p11.22p11.21), and der(18)dup(p11. 22p11.21)inv(18)(p11.22q21.31), or both the terminal del/dup and the interstitial duplication occurred simultaneously.

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Prenatal diagnosis and molecular cytogenetic characterization of a de novo interstitial duplication of 14q (14q31.3→q32.12) associated with abnormal maternal serum biochemistry

Taiwanese Journal of Obstetrics and Gynecology ◽

10.1016/j.tjog.2012.08.002 ◽

2013 ◽

Vol 52 (1) ◽

pp. 125-128 ◽

Cited By ~ 8

Author(s):

Chih-Ping Chen ◽

Kwui-Shuai Hwang ◽

Her-Young Su ◽

Shuan-Pei Lin ◽

Yi-Ning Su ◽

...

Keyword(s):

Prenatal Diagnosis ◽

De Novo ◽

Serum Biochemistry ◽

Maternal Serum ◽

Molecular Cytogenetic ◽

Interstitial Duplication ◽

Cytogenetic Characterization

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Characterization of a Complex Derivative Chromosome 18

Cancer Genetics ◽

10.1016/j.cancergen.2016.05.058 ◽

2016 ◽

Vol 209 (5) ◽

pp. 247-248

Author(s):

Andrea Penton ◽

Blair K. Stevens ◽

Peter Papenhausen

Keyword(s):

Derivative Chromosome ◽

Chromosome 18 ◽

Complex Derivative

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Identification and Molecular Characterization of a de novo Supernumerary Ring Chromosome 18 in a Patient with Klippel-Trenaunay Syndrome

Annals of Human Genetics ◽

10.1046/j.1529-8817.2004.00095.x ◽

2004 ◽

Vol 68 (4) ◽

pp. 353-361 ◽

Cited By ~ 34

Author(s):

A. Anil Timur ◽

Azita Sadgephour ◽

Michael Graf ◽

Stuart Schwartz ◽

Eric D. Libby ◽

...

Keyword(s):

Molecular Characterization ◽

De Novo ◽

Ring Chromosome ◽

Chromosome 18 ◽

Klippel Trenaunay Syndrome ◽

Ring Chromosome 18

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Molecular characterization of a complex small supernumerary marker chromosome derived from chromosome 18p: an addition to the literature

Molecular Cytogenetics ◽

10.1186/s13039-020-00519-w ◽

2021 ◽

Vol 14 (1) ◽

Author(s):

Eleonora Marchina ◽

Michela Forti ◽

Mariella Tonelli ◽

Stefania Maccarini ◽

Francesca Malvestiti ◽

...

Keyword(s):

Intellectual Disability ◽

Molecular Characterization ◽

De Novo ◽

Marker Chromosome ◽

Uniparental Disomy ◽

Chromosomal Microarray ◽

Chromosomal Microarray Analysis ◽

Specific Syndrome ◽

Trisomy 18P

Abstract Background Small supernumerary marker chromosomes (sSMC) are a heterogeneous group of structurally abnormal chromosomes, with an incidence of 0,044% in newborns that increases up to almost 7 times in developmentally retarded patients. sSMC from all 24 chromosome have been described, most of them originate from the group of the acrocentric, with around half deriving from the chromosome 15. Non-acrocentric sSMC are less common and, in the 30 percent of the cases, are associated with phenotypic effect. Complex sSMC consist of chromosomal material derived from more than one chromosome. Genotype–phenotype correlations in patients with sSMC are difficult to assess. Clinical features depend on factors such as its size, genetic content, the involvement of imprinted genes which may be influenced by uniparental disomy and the level of mosaicism. Trisomy of the short arm of chromosome 18 (18p) is an infrequent finding and does not appear to be associated with a specific syndrome. However, mild intellectual disability with or without other anomalies is reported in almost one-third of the patients. Case presentation Here we present clinical and molecular characterization of a new case of de novo complex sSMC consisting of the entire short arm of chromosome 18p associated with a centromere of either chromosome 13 or 21, evidenced in a 5-year-old boy during diagnostic workup for moderate intellectual disability and dysmorphisms. To date, only seven cases of isolated trisomy 18p due to a sSMC have been reported, three of which have been characterized by array CGH. In two of them the breakpoints and the size of the duplication have been described. In the manuscript we also reviewed cases reported in the DECIPHER database carrying similar duplication and also considered smaller duplications within the region of interest, in order to evaluate the presence of critical regions implicated in the pathological phenotype. Conclusions Our case provides additional information about phenotypic effects of pure trisomy 18p, confirms chromosomal microarray analysis as gold standard to characterize complex sSMC, and supplies additional elements for genetic counselling.

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