title: [Fragile X syndrome and white matter abnormalities: Case study of two brothers].
abstract: Fragile X syndrome is the most usual cause of hereditary intellectual deficiency. Typical symptoms combine intellectual deficiency, social anxiety, intense emotional vigilance, and a characteristic facial dysmorphy. This is subsequent to a complete mutation of the FMR1 gene, considering a semidominant transmission linked to the unstable X. The expansion of the CGG triplet greater than 200 units combined with a high methylation pattern lead to a transcriptional silence of the FMR1 gene, and the protein product, the FMRP, is not synthesized. This protein is involved in synaptic plasticity. Brain MRI can show an increased volume of the caudate nucleus and hippocampus, combined with hypoplasia of the cerebellar vermis. Fragile X Associated Tremor Ataxia Syndrome (FXTAS) syndrome is a neurodegenerative disorder occurring in carriers of the premutation in FMR1. Brain MRI shows an increased T2 signal in the middle cerebellar peduncles. This syndrome is linked to a premutation in the FMR1 gene. We report here the case of two brothers presenting a typical fragile X symptomatology. Brain MRI showed hyperintensities of the middle cerebellar peduncles. Such MRI findings support the assumption of a genetic mosaicism.
authors.affiliation: Unité de neuropédiatrie, hôpital des enfants, CHU Purpan, 330, avenue de Grande-Bretagne, TSA 70034, 31059 Toulouse cedex 9, France. Electronic address: elisabethwallach@hotmail.com.
authors.forename: E
authors.initials: E
authors.lastname: Wallach
authors.affiliation: Service de génétique médicale, CHU Purpan, 330, avenue de Grande-Bretagne, 31059 Toulouse cedex 9, France.
authors.forename: E
authors.initials: E
authors.lastname: Bieth
authors.affiliation: Service de neuroradiologie, CHU Purpan, 330, avenue de Grande-Bretagne, 31059 Toulouse cedex 9, France.
authors.forename: A
authors.initials: A
authors.lastname: Sevely
authors.affiliation: Unité de neuropédiatrie, hôpital des enfants, CHU Purpan, 330, avenue de Grande-Bretagne, TSA 70034, 31059 Toulouse cedex 9, France.
authors.forename: C
authors.initials: C
authors.lastname: Cances
mesh_terms: D001921:Brain / Q000473:pathology; D002675:Child, Preschool; D004252:DNA Mutational Analysis; D051860:Fragile X Messenger Ribonucleoprotein 1 / Q000235:genetics; D005600:Fragile X Syndrome / Q000175:diagnosis* / Q000235:genetics*; D006580:Genetic Carrier Screening; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D009030:Mosaicism; D010641:Phenotype; D019680:Trinucleotide Repeat Expansion / Q000235:genetics; D066127:White Matter / Q000002:abnormalities*
chemical_list: D051860:Fragile X Messenger Ribonucleoprotein 1; C497683:FMR1 protein, human