A Cytogenetic Study in 120 Turkish Children with Intellectual Disability and Characteristics of Fragile X Syndrome

Abstract

We review the evidence for the frequency of the fragile X syndrome (FXS), other X-linked abnormalities, and other chromosomal disabilities of Turkish pediatric psychiatry outpatients with intellectual disability. Reported clinical features and genetic findings were used in cytogenetic screenings to estimate the prevalence of the fragile X (fra X) and other chromosomal aberrations in 120 patients with mental retardation, language disorders, attention deficit hyperactivity, or developmental delay, in comparison with 30 healthy children. Data on the clinical, intellectual and behavioral findings in 14 fra X positive children (11.7%) is presented. Ten of the 120 patients (8.3%) had enlargement of the heterochromatin region of chromosome 9. Other chromosomal aberrations and autosomal fragile sites (FS) were also observed. There was a statistically significant difference in the autosomal and X-linked FS between the study and control groups (p < 0.05). The tests for the fra X chromosome are likely to be of diagnostic benefit in young children with autism or developmental delay, particularly in speech, and who have large and prominent ears.

Genetic testing in children with autism spectrum disorders

“…16 Similarly, inversion of chromosome 9, associated with mental retardation and dysmorphic features 17,18 is also seen in patients with ASD. 18,19 Abnormalities of chromosomes 13p, 20 variation in heterochromatin regions 9qh+ 21,22 and Yqh+ 19 are other chromosome abnormalities shown in autistic children or children having autistic features similar to our study. Yqh+ is considered as clinically nonsignificant polymorphism.…”

Common Clinical Characteristics and Rare Medical Problems of Fragile X Syndrome in Thai Patients and Review of the Literature

“…In East and South East Asians studies, the prevalence of elongated face was higher in a Korean (90%) [21] than in Thai (48%) prepubertal boys with FXS ( p = 0.015). For Turkish prepubertal boys with FXS, elongated face was statistically different between studies (83% versus 29%, p < 0.001) [14, 15]. These studies indicate that even in young individuals with FXS, there is a wide variation of facial features among ethnicities and even within the same ethnicity.…”

“…Approximately 52% of prepubertal boys younger than 8 years old had testicular volumes greater than the 95th percentile, comparable with a study by Butler et al 1991 [39], which found that more than 50% of boys with FXS had testicular volumes greater than the 95th percentile. Studies in males with FXS younger than 20 years old have found that macroorchidism was not very common in middle east countries (Turkey, Saudi Arabia, and Egypt), with frequencies of 11–23%, 15%, and 21%, respectively, while it was more common in Thais and Koreans, with frequencies of 53% and 70%, respectively [13–15, 17, 21]. For Americans with FXS younger than 20 years of age, macroorchidism was observed in frequencies ranging from 19% to 63% [6–8].…”

“…Various studies have found that hyperactivity and/or attention deficit were common among both Caucasians and Asians with FXS (Table 1). Hyperactivity and/or attention deficit were observed as the most common features in FXS in some studies [15, 17, 21, 46]. Symptoms have been found to manifest even in high-functioning boys with FXS, although in such patients the symptoms usually improved with age [4].…”

Prevalence of Fragile X Syndrome among children receiving special education and carrier states in first degree relatives.

“…Prevalence among males was 2.03%. Prevalence rates ranging from 0.3% to 11.7% have been reported from similar populations of intellectually impaired individuals [10,25]. This wide variation could be explained on the basis of other biological differences in the nature of the study samples as well as the techniques of DNA analysis.…”