Contributed by Deepak Mohan MD, Deborah Ketterer, Sally Kochmar , Urvashi Surti, PhD
Published on line in June 2003
The teenager living in a group home with history of severe behavior problems including acting out and hair pulling has a neurology consult due to possible seizures. The measured Intelligence Quotient was approximately 40. No identification of father was possible and the mother was unavailable due to diagnosis of paranoid schizophrenia and placement in another group home.
FISH for Angelman Syndrome was performed due to prominent jaw (despite normal gait and verbal skills).
FIG1 FISH for Angelman Syndrome
D15S10 (15q11-q13)Red - Angelman syndrome locus
pml (15q22) red & D15Z1 (centromere) green - internal marker probes FISH results did not show a deletion for the D15S10 Angelman syndrome critical region.
More information on fish
Fluorescence In Situ Hybridization (FISH) is a technique that allows DNA sequences to be detected on metaphase chromosomes or in interphase nuclei of fixed cultured or uncultured cytogenetic samples. The technique uses DNA probes that hybridize to entire chromosomes or single unique sequences, and serves as a powerful adjunct to classic cytogenetics. Target DNA, after fixation, is treated with heat and formamide to denature the double-stranded DNA, rendering it single stranded. The target DNA is thus available for annealing to a similarly denatured, single-stranded, fluorescently labeled DNA probe that has a complementary sequence. Following hybridization, unbound and non-specifically bound DNA probe is removed by a series of stringent washes and the DNA counterstained for visualization. Fluorescence microscopy then allows the visualization of the hybridized probe on the target material.