Fragile X syndrome: clinical and cytogenetic studies

Abstract

Three families with the fragile X syndrome were studied with the aim to establish the most frequent clinical signs in the affected individuals and heterozygous women. The clinical evaluation, IQ level measurements and cytogenetic studies were performed in 40 subjects, 20 males and 20 females. The fragile X diagnosis was confirmed in all the male individuals with mental retardation. In the postpubertal subjects the most frequent clinical signs were inner canthal distance < 3.5 cm, macro-orchidism, long and narrow face and high arched palate while in the prepubertal subjects the behavioral characteristics as hyperactivity and poor eye contact were the most frequent and were observed in all patients. Twenty six percent of the heterozygous women presented with mental retardation and showed clinical signs rather than behavioral ones. All male individuals with mental retardation were observed as having fragile X [fra(X)] in lymphocytes culture. Sixty three percent of women showed fra(X). There was a positive correlation between the frequency of fra(X) and the clinical characteristics. We emphasize the importance of the clinical evaluation in the study of familial mental retardation and in the screening of isolated cases with suspect of having the fragile X syndrome.

Características físicas e bucais na síndrome do X frágil – revisão de literatura

“…Os portadores não afetados da mutação têm um número aumentado de repetições, geralmente entre 60 e 200, caracterizada como uma pré-mutação. Indivíduos com retardo mental e mutação completa têm mais de 200 repetições 6,8 .…”

“…As manifestações comportamentais nesses indivíduos assemelham-se ao autismo, como o déficit de atenção, a dificuldade na interação social, a timidez, a ansiedade, a labilidade emocional, os movimentos estereotipados de mãos 5,6 , além de hiperatividade e contato ocular pobre 5 .…”

“…As características bucais frequentemente encontradas em pacientes portadores da Síndrome do X frágil são: palato estreito e profundo, prognatismo mandibular, macroglossia, má higiene, hipoplasia de esmalte, má oclusão, presença de biofilme e/ou cárie, cálculo e gengivite. A deficiência mental é um fator que dificulta a abordagem odontológica desses pacientes, pois existem características comportamentais, como autismo e hiperatividade, que exigem atenção multidisciplinar 6 .…”

Research Article Molecular Diagnosis of X-Fragile Syndrome: Perspectives for the Public Health System in the Central Region of Brazil

“…Above 200 CGG repeats the gene tends to be methylated, preventing its transcription and synthesis of the FMRP protein (Bagni et al, 2012). This protein is responsible for several biological functions in the brain, controlling the gene expression in the signaling of several receptors (Felix and Pina-Neto, 1998). According to França et al (2012), any alteration of the FMR1 gene that results in the absence or deficit of the FMRP protein, would lead to the reduction of synaptic plasticity, fundamental to the learning and memory processes.…”

Συμβολή στη φυσική χαρτογράφηση και στον εντοπισμό γονιδίων της περιοχής q14-q24 του χρωμοσώματος 6 στον άνθρωπο.

“…Εξάλλου στο 6q21 υπάρχει η εύθραυστη θέση FRA6F . Τέτοιες θέσεις στα χρωμοσώματα είναι γνωστό ότι έχουν συσχετισθεί με ασθένειες (Felix et al, 1998), γήρανση και αστάθεια των χρωμοσωμάτων (Hewett et al, 1998).…”