Microdeletions of chromosome 17p13.3 markers in an unselected survey of probands with type I lissencephaly
- and others
Type I lissencephaly (MIM No.247200, McKusick, 1992), a brain malformation characterized by a smooth cerebral surface, exhibits a four-layered cortex and leads to mental retardation and other neurological anomalies. Lissencephaly, type I occurs either isolated (ILS) or in association with dysmorphic facial features (Miller-Dieker syndrome, MDS). Microdeletions were detected within a 350 kb critical segment in 17p13.3 in about 13% of patients with ILS and about 90% with MDS. Most of these patients were selected for molecular analysis, however, by an already known abnormal karyotype. Therefore, the diagnostic value of microsatellite and VNTR markers to identify deletions in unselected ILS/MDS patients is still unknown. We have tested the respective significance of a novel (CA)17 VNDR element (D17S379) and of the VNTR marker YNZ22 (D17S5) to identify deletions in an unselected survey of 28 ILS/MDS patients. For D17S379, 50% of our patients were heterozygous, while 46% were uninformative with respect to segregation of alleles within their family. One patient (3.6%) was shown to be deleted for a paternal allele. PCR for D17S5, which maps proximal to the ILS region, disclosed a deletion in 3 patients (10.7%), including the one seen also by D17S379. Altogether, 75% were heterozygous and only 14% uninformative for this locus. Our results suggest that the combined PCR analysis for two of the most significant markers within the ILS/MDS region disclose a deletion in about 10% of unselected patients with features of type I lissencephaly. The low frequency of deletions detected may reflect different mutation mechanisms, genetic heterogeneity, the need for more densely spaced markers around the critical region, and/or more strict clinical criteria for defining the study group.
- OSTI ID:
- 133298
- Report Number(s):
- CONF-941009--
- Journal Information:
- American Journal of Human Genetics, Journal Name: American Journal of Human Genetics Journal Issue: Suppl.3 Vol. 55; ISSN AJHGAG; ISSN 0002-9297
- Country of Publication:
- United States
- Language:
- English
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