FMR2 gene deletion as a cause of non-specific mental retardation and autistic behavior in two brothers

Abstract

Background: Silencing of the Fragile X Mental Retardation 2 gene (FMR2, Xq28) as a consequence of CCG trinucleotide repeat expansion located upstream of the gene is the cause of non-specific X-linked mental retardation (MRX) in 1/50.000 newborn males. This condition, also known as FRAXE, represents a mild to borderline form of mental retardation (MR) associated with communication deficits, attention problems, hyperactivity, and autistic behavior. Little is known about FMR2 deletions as potential cause of FRAXE in the absence of trinucleotide expansion. Several reports on large deletions including FMR1, FMR2 and other adjacent genes exist. However, reports on alterations affecting only FMR2 are to our knowledge limited to descriptions of a balanced translocation having the breakpoint within the FMR2 gene and two submicroscopic deletions which originally led to the cloning of the FMR2 gene.