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Figure 1 | BMC Bioinformatics

Figure 1

From: An experimental loop design for the detection of constitutional chromosomal aberrations by array CGH

Figure 1

BAC-based Array CGH. Wolf-Hirschhorn syndrome was discovered in 1961 by Herbert Cooper and Kurt Hirschhorn. The phenotypical features include mental retardation, distinct facial appearance (typical Greek warrior helmet faces, high forehead), and seizures. Wolf-Hirschhorn is characterized by a deletion of the end of the short arm of chromosome 4; in particular, a deletion of the terminal band (4p16.3) is essential for full expression of the phenotype. Wolf-Hirschhorn can be detected with array CGH by comparing a genomic DNA sample of the patient (test) with that of a normal individual (reference). DNA extracted from test and reference sample is labeled with different fluorescent dyes (typically Cy3 and Cy5) and hybridized to the microarray. Array CGH probes can be PCR-amplified Bacterial Artificial Chromosomes or BAC clones or spotted long oligos. The microarray is scanned by two-channel laser scanner and aneuploid chromosomal regions are detected as probes with a deviant log ratio. This example clearly indicates a deviation of the log ratios at the end of the short arm of chromosome 4 and allows to confirm the hypothesis of Wolf-Hirschhorn syndrome.

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