Automated Detection of Gene Duplications or Deletions

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DESCRIPTION (provided by applicant): This project will further develop automated instrumentation and image analysis techniques to detect gene duplications or deletions in interphase FISH, which are difficult to detect by routine cytogenetics. There is a growing list of genetic disorders that result from chromosomal anomalies, related to either duplications or deletions. These include: (1) neuropathies; Charcot-Marie-Tooth Disease (CMT1A) and Hereditary Neuropathy with Pressure Palsies (HNPP), (2) neurological disorders; Pelizaeus-Merzbacher Disease (PMD) and X-Linked Spastic Paraplegia (SPG2), (3) muscular wasting disorders; Duchene (DMD) and Becker Muscular Dystrophy (BMD), (4) contiguous-gene syndromes; Smith-Magenis Syndrome (SMS). Our approach is to use readily available DNA probes, followed by automated genetic screening to detect duplications/deletions. We will develop an imaging system for the automated identification of interphase cells, and use sophisticated image analysis for high-resolution detection and separation of microscopic rearrangements. In the Phase I project we evaluated the feasibility of newly developed imaging algorithms, for effectively and precisely identifying the separation of FISH dot duplicates. Algorithms were developed for automatically (1) segmenting dots, (2) computing the integrated fluorescence intensity of dots, (3) determining the separation distance, and (4) classifying duplicates and single dots. In Phase II we will incorporate the newly developed imaging algorithms into our automated imaging system, and test the prototype clinically. We will also develop and implement three-dimensional modeling techniques to obtain an unbiased estimate of the spatial distance between duplicated genes. Phase III will commercialize the instrument. Computer automation will make genetic screening practical on a large scale by reducing costs and relieving humans of tedious duties. This approach will be most valuable to medical genetics, particularly for screening CMT1A/HNPP, PMD/SPG2, DMD/BMD, and SMS. Duplications have also been identified for the Prader-Willi /Angelman syndrome region that result in autism. Duplications, such as for 22ql 1.2 and 17pl 1.2 have been described and result in a rather mild phenotype. But duplications of the Williams syndrome region have not been described and thus, the phenotype is unknown. The ability to screen patients for duplications by interphase FISH analysis will likely identify a large number of individuals that would benefit from medical intervention. It may uncover syndromes that previously had no identifiable etiology. This will provide a screening test and eventually a diagnostic test for those individuals with perhaps mild phenotypes, such as learning disabilities.