J Korean Med Sci.  2010 Dec;25(12):1798-1801. 10.3346/jkms.2010.25.12.1798.

Partial Tetrasomy of Chromosome 22q11.1 Resulting from a Supernumerary Isodicentric Marker Chromosome in a Boy with Cat-eye Syndrome

• Ko JM
• Kim JB
• Pai KS
• Yun JN
• Park SJ

• KMID: 1792906
• DOI: http://doi.org/10.3346/jkms.2010.25.12.1798

Abstract

The 22q11 region has been implicated in chromosomal rearrangements that result in altered gene dosage, leading to three different congenital malformation syndromes: DiGeorge syndrome, cat-eye syndrome (CES), and der(22) syndrome. Although DiGeorge syndrome is a common genomic disorder on 22q11, CES is quite rare, and there has been no report of Korean CES cases with molecular cytogenetic confirmation. In this study, we present the phenotypic and genetic characteristics of a 3-month-old boy with CES. Clinical findings included micropthalmia, multiple colobomata, and renal and genital anomalies. Cytogenetic analyses showed the presence of a supernumerary marker chromosome, which was identified as a bisatellited and isodicentric chromosome derived from an acrocentric chromosome. The results of array comparative genomic hybridization and fluorescence in situ hybridization studies confirmed the karyotype as 47,XY,+mar.ish idic(22)(q11.1) (D22S43+).arr 22q11.1(15,500,000-15,900,000)x4, resulting in a partial tetrasomy of 22q11.1. To the best of our knowledge, this is the first report in Korea of CES confirmed by cytogenetic and molecular cytogenetic analyses.

Keyword

Trisomy 22; Cat Eye Syndrome; Supernumerary Marker; Microphthalmos; Renal Dysplasia

MeSH Terms

Abnormalities, Multiple/genetics
Aneuploidy
Chromosome Disorders/diagnosis/genetics
*Chromosomes, Human, Pair 22/genetics
Coloboma/genetics
Craniofacial Abnormalities/genetics
Genetic Markers
Humans
In Situ Hybridization, Fluorescence
Infant
Karyotyping
Male
Phenotype
*Tetrasomy
Ultrasonography, Prenatal

Figure

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  Fig. 1 A supernumerary bisatellited marker chromosome was identified by (A) GTG, (B) CTG, and (C) Nucleolar Organizing Region banding chromosome analyses of the present patient.

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  Fig. 2 Array comparative genomic hybridization profile from chromosome 22 displays a partial duplication of chromosome 22q11.1 in the present patient. Log 2 ratio values for all probes are plotted as a function of their chromosome position. Locations of probes with Log 2 ratios of greater than 0.25 are suggested to be the duplicated region.

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  Fig. 3 The FISH result with a probe of the CES critical locus on 22q11.1 (D22S43) shows two normal hybridization signals on chromosomes 22 and duplicated hybridization signals on the CES chromosome.

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