Grandmaternal origin of an isochromosome 18p present in two maternal half-sisters

Boyle, Jane; Sangha, Karan; Dill, F. J.; Robinson, Wendy P.; Yong, Siu Li

doi:10.1002/ajmg.1295

Cited by 28 publications

(33 citation statements)

References 9 publications

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“…The i(18p) syndrome has a well-described phenotype, with more than 75 cases reported in the literature [Callen et al, 1990;reviewed in Schinzel, 2001]. There have also been cases of familial recurrence consistent with parental germline mosaicism [Boyle et al, 2001]. We found several features of the i(18p) phenotype in our patient, including microcephaly, dysmorphic ears, long philtrum, narrow digits, and anteriorly-placed anus.…”

Section: Discussionsupporting

confidence: 58%

DiGeorge anomaly in a patient with isochromosome 18p born to a diabetic mother

DeBerardinis¹,

Medne²,

Spinner³

et al. 2005

American J of Med Genetics Pt A

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The DiGeorge anomaly (DGA) is an etiologically heterogeneous developmental field defect in which cardiovascular malformations, hypocalcemia, thymic hypoplasia, and characteristic dysmorphisms are major clinical features. The 22q11.2 deletion is the most common single etiology of DGA, although a number of other chromosomal abnormalities and teratogens, including maternal diabetes, have been implicated as well. We present a patient, born to a diabetic mother, with interrupted aortic arch type B (IAA-B), neonatal hypocalcemia, thymic hypoplasia, and dysmorphic features including microcephaly, thick, overfolded helices, and anteriorly-placed anus. Cytogenetic studies showed the presence of a marker chromosome, identified by fluorescence in-situ hybridization (FISH) as an isochromosome 18p [i(18p)]. We did not detect a 22q11.2 deletion by FISH using a cosmid probe corresponding to locus D22S75. The patient is the first example of either DGA or IAA-B in a patient with i(18p). We review the genetic abnormalities associated with DGA, and discuss the potential contributions of maternal diabetes and i(18p) in our patient.

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Section: Discussionsupporting

confidence: 58%

DiGeorge anomaly in a patient with isochromosome 18p born to a diabetic mother

DeBerardinis¹,

Medne²,

Spinner³

et al. 2005

American J of Med Genetics Pt A

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“…The majority of 18p isochromosomes seem to be de novo anomalies, like the 2 cases reported in the present work; however, there are also familial cases in the literature [Boyle et al, 2001]. The first small supernumerary 18p isochromosome, designated i(18p), was originally described by Froland et al [1963].…”

supporting

confidence: 63%

Different Conformation of Two Supernumerary 18p Isochromosomes, One with a Concomitant Partial 18q Trisomy

Dutra

Mancini²,

Takeno³

et al. 2012

Cytogenet Genome Res

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The presence of a supernumerary 18p isochromosome is a rare chromosomal abnormality that results in 18p tetrasomy. This is a report on the clinical, cytogenetic and molecular findings of 2 non-related patients with a supernumerary 18p isochromosome. Both patients present some features of the 18p tetrasomy syndrome (strabismus, low-set ears, long and narrow fingers and toes), but additional characteristics were also observed. Cytogenetic analysis, FISH, MLPA and SNP array techniques showed that one of the isochromosomes is symmetric and monocentric, while the other is asymmetric and dicentric, yet resulting in a similar tetrasomy of the 18pter–18p10 region, followed by a partial 18q11.2 trisomy, an unprecedented finding in the literature.

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“…Isochromosomes are supernumerary marker chromosomes, that are made up of two copies of the same arm of a chromosome, so that they form a mirror image of each other, resulting in a tetrasomy of the arm involved (Boyle et al 2001;Ramegowda et al 2006). Prevalence of various kinds of isochromosomes range from 0.14 to 0.72 per 1000 live births (Boyle et al 2001;Ramegowda et al 2006).…”

Section: Introductionmentioning

confidence: 99%