Screening microdeletion by FISH method (Fluoresan In Situ Hybridization) in patients with Miller-Dieker and Angelman, Prader-Willi syndromes

1-2 SUMMARY Prader-Willi syndrome (PWS) is a neuroendocrine disorder characterized by central muscular hypotonia, nutritional disorders, thrive failure in infants. The most common features of the syndrome are fasial dismorphism, hypogonadism, cryptorchidism, short stature, short hands and feets, and mental retardation. Obesity caused by hyperphagia has been usually added to clinical picture in the early childhood stage. Angelman syndrome (AS) is characterized by mental reterdation, absense of speech, paroxysms of laughter, ataxic jerky movements, microcephaly, seizures, an abnormal electrocephalogram (EEG) pattern, with protruding tongue, and prognathism. Miller-Dieker syndrome (MDS) is a multiple malformation syndrome characterized by type I lissencephaly and characteristic facial appearance. In addition to the lissencehaly, a severe mental retardasyon, prominent forehead, bitemporal narrowness, a short nose with to turn up nares, protuberant upper lip, and small jaw is present the findings in Miller-Dieker syndrome. About %70 of patients with Prader-Willi syndrome and Angelman syndrome have a common interstitial de novo microdeletion encompassing paternal or maternal loci D15S9 to D15S12. Most of the Prader-Willi syndrome patients and a small number of. Angelman syndrome patients have a maternal or paternal uniparental disomy (UPD) 15, respectively. Other chromosome 15 rearrangements and a few smaller atypical deletions associated with an abnormal methylation pattern, are rarely to be seen. Microdeletions of chromosome 17pl3.3 also known as the Miller-Dieker artical region, have been associated whith both Miller-Dieker syndrome and isolated lissensephaly syndrome. Normal chromosomes are present in %90 but others are associated with chromosomal abnormalities which include deletion of the short arm in association with the duplication of long arm of chromosome 17, ring chromosome 17, and 12q:17p translocation. SNRPN/IC and 15qter telomere spesific probs for 15qll-13 region in Prader Willi / Angelman syndrome cases; MDS/ILS and SMS probs for 17pl3.3 region in Miller-Dieker syndrome cases were used by FISH technique. The results of FISH in 12 cases with Prader Willi / Angelman syndrome and 13 cases with Miller-Dieker and lissencephaly who were dianosed according to the clinical assessment; were compared with the cytogenetic findings of those cases. No microdeletion or cytogenetic anomaly was detected in all patients.n-ı In both group ( 25 patients ) no microdeletion was detected FISH method has been reported that is the first choice to investigate the microdeletion in Prader Willi / Angelman syndrome and Miller-Dieker syndrome patient. In this study having no patient with microdeletion generated a thought of being more cautious in clinical diagnosis. It is considered that the FISH method used in this study can be performed routinely in our laboratory since all patients chromosomes showed fluorescent signals in the loci investigated.