Journal article

Transcript levels of the intermediate size or grey zone fragile X mental retardation 1 alleles are raised, and correlate with the number of CGG repeats

Danuta Z Loesch, Quang M Bui, Richard M Huggins, Robert J Mitchell, Randi J Hagerman, Flora Tassone

JOURNAL OF MEDICAL GENETICS | BMJ PUBLISHING GROUP | Published : 2007

Abstract

BACKGROUND: Grey zone or intermediate alleles are one of the three recognised classes of the X-linked fragile X mental retardation 1 (FMR1) gene showing intergenerational instability. These classes are defined according to the number of CGG repeats in the FMR1 5'-untranslated region. Although large CGG expansions (>200 repeats) cause a neurodevelopmental anomaly through silencing of the gene, resulting in a deficit of FMR1 specific protein, smaller expansions (approximately 55-200 repeats) are associated with an increased transcription and late-onset specific phenotypes. Those alleles with a CGG repeat number ranging between approximately 41 and 55 are relatively poorly defined with regard t..

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