ABSTRACT
Pallister-Killian syndrome (PKS) is a rare inherited disease with multiple congenital anomalies, profound intellectual disability, and the presence in the karyotype of sSMC - i(12)(p10). The frequency of PKS may be underestimated due to problems with cytogenetic diagnosis caused by tissue-specific mosaicism and usually a low percentage of peripheral blood cells containing sSMC. Such tissue-specific mosaicism also complicates a detailed analysis of the sSMC, which, along with the assessment of mosaicism in different tissues, is an important part of cytogenetic diagnosis in PKS. Unfortunately, a full-fledged diagnosis in PKS is either practically impossible or complicated. On the one hand, this is due to problems with the biopsy of various tissues (skin biopsy with fibroblast culture is most often used in practice); on the other - a low percentage of dividing peripheral blood cells containing sSMC, which often significantly complicates the analysis of its composition and organization. In the present study, a detailed analysis of sSMC was carried out in a patient with a characteristic clinical picture of PKS. A relatively high percentage of peripheral blood cells with sSMC (50%) made it possible to perform a detailed molecular cytogenetic analysis of de novo sSMC using chromosomal in situ suppression hybridization (CISS-hybridization), multicolor FISH (mFISH), multicolor chromosome banding (MCB), array CGH (aCGH), and quantitative real-time PCR (qPCR), and short tandem repeat (STR) - analysis. As a result, it was found that the sSMC is not a typical PKS derivative of chromosome 12. In contrast to the classical i(12)(p10) for PKS, the patient's cells contained an acrocentric chromosome consisting of 12p material. Clusters of telomeric repeats were found at the both ends of the sSMC. Furthemore, the results of aCGH and qPCR indicate the presence of interstitial 8.9 Mb duplication at 12p13.1-p12.1 within the sSMC, which leads to different representations of DNA from different segments of 12p within cells containing sSMC. The obtained data raise the question of the instability of the sSMC and, as a consequence, the possible presence of additional rearrangements, which, in traditional cytogenetic analysis of patients with PKS, are usually described as i(12)(p10).
ABSTRACT
In this study authors searched for chromosomal aberrations in 71 children with developmental delay or idiopathic mental retardation using Human Genome CGH Microarray Kits 4×44K and 8×60K (Agilent Technologies, USA). Microdeletions and microduplications, as well as CNV, which may be related to intellectual disability and associated with regions of known hereditary diseases or chromosomal syndromes were identified in 14 (20%) children (these patients are described in this article). During the analysis, candidate genes localized within the regions of aberrations and associated with development and functioning of nervous system were denoted.
Subject(s)
Comparative Genomic Hybridization , Intellectual Disability/genetics , Adolescent , Child , Female , Gene Deletion , Gene Duplication , Humans , Intellectual Disability/diagnosis , MaleABSTRACT
Comparative Genomic Hybridization (CGH) is a molecular cytogenetic analysis that allows identification of genomic changes by comparing the copy number of DNA sequences in cells of tested tissue and the reference specimen. CGH is based on competitive suppressive in situ hybridization of two differently labeled DNA probes (tested and reference, karyotypically normal, fluorochrome-labeled DNAs) with metaphase chromosomes of a healthy subject. First described by Kallioniemi et al. in 1992, the CGH assay has been widely used for identification and characterization of both numerical and structural chromosome abnormalities in cells of different tissues at various pathological conditions in humans, especially in tumor diseases. We discuss the specific features and quality control of comparative genomic hybridization, its advantages and limitations in detection of genomic imbalance and the prospects for development of this technology.
Subject(s)
Genome, Human , In Situ Hybridization/methods , Chromosomes, Human , Humans , Neoplasms/genetics , Quality Control , Sensitivity and SpecificityABSTRACT
Comparative genomic hybridization (CGH) technique was used to examine a set of ten spontaneous abortions whose cell cultures were characterized by the lack of proliferation in vitro, and thereby, were not available for the analysis by means of routine cytogenetic methods. Five abortions (50%) had aneuploidy of autosomes, including trisomy 10, 14, 18, and 21, and monosomy 22. The latter variant of unbalanced chromosomal abnormalities is rarely detected in spontaneous abortions by use of conventional cytogenetic methods. The results were validated by using fluorescent in situ hybridization (FISH) analysis with centromere-specific DNA probes. Embryos with trisomy 10 and monosomy 22 displayed mosaicism with the frequencies of abnormal cell clones constituting 68 and 33% respectively. The advantages and limitations of the applying of CGH technique for detection of genomic abnormalities in both nonmosaic and mosaic forms are discussed.
