Frequency of fragile-x in x-linked mental retardation
Joint Authors
al-Sobky, Izzat S.
Abu al-Ula, Suhayr
Tawfiq, Maha A.
Muhammad, Wafa M.
Source
The Egyptian Journal of Medical Human Genetics
Issue
Vol. 9, Issue 2 (30 Nov. 2008), pp.237-248, 12 p.
Publisher
Egyptian Society of Human Genetics
Publication Date
2008-11-30
Country of Publication
Egypt
No. of Pages
12
Main Subjects
Topics
Abstract EN
Introduction : fragile X syndrome (FXS) is the most common form of inherited mental retardation and accounts for about one third of all cases of X linked mental retardation (XLMR).
It is inherited as an X-linked dominant trait with a fragile site at Xq27.3 locus named fragile X mental retardation gene (FMR-1).
The FMR-1 protein is widely expressed, with the highest expression in brain, testes, ovaries, esophagus, thymus, eye and spleen.
Patient and Methods : this study was conducted on twenty mentally retarded boys aged 8.5 ± 3.84 years, attending the genetic clinics at Menoufiya University hospitals.
They represented 11 families.
All patients were subjected to detailed history, family pedigree, anthropometric measurements, thorough clinical examination with clinical scoring for the 13 items fragile X checklist, IQ assessment, routine investigations and cytogenetic studies which included conventional karyotyping using G banding and cytogenetic analysis for fragile X detection.
Positive consanguineous marriage was found in 15 % of our studied cases.
Nine families out of total eleven families had positive family history most of them were second degree relative males through maternal cousins.
Results : craniofacial abnormalities included high arched palate in 65 % of patients, large ears in 55 %, prominent forehead in 45 % and elongated face and abnormal teeth in 30 % for each.
Speech problems were present in 75 % and hyperactivity in 55 % of patients.
Sixty five percent had mild mental retardation (IQ= 50-70 %).
By applying the clinical scoring fragile X checklist, it was found that 3 patients (15 % >) had score more or equal to 19 and 3 (15 %) had score from 16 to less than 19, while 14 (70 %) had score less than 16.
As regards cytogenetic studies, 80 % of our patients had normal karyotyping (46 XY) while four cases (20 %) had positive fragile site on X-chromosome of whom two cases from the same family had 46, Y, Frg (X) (q27.3), while the other two cases, also from a single family, had inversion of Y chromosome beside positive fragile X chromosome site 46, Fra(X) (q27.3), inv (Y).
Conclusion: So, in a child with isolated mental retardation or autism of unknown etiology with considerable fragile X dimorphic features or established family history of fragile X syndrome, chromosomal study that identifies the fragile site at Xq27.3 in addition to other cytogenetic abnormalities could be useful or early diagnosis and intervention by a special services team.
The present study revealed that the role of cytogenetic analysis in the diagnosis must be reevaluated since it can determine chromosomal abnormalities including the fragile X site with one single test, especially with unavailability of molecular techniques and their high costs.
A national multicenter genetic study of fragile X syndrome among affected children and their families is recommended to define our indications and steps of early diagnosis, population screening strategy, genetic counseling guidelines for different pheno-types and early intervention policies.
American Psychological Association (APA)
al-Sobky, Izzat S.& Abu al-Ula, Suhayr& Tawfiq, Maha A.& Muhammad, Wafa M.. 2008. Frequency of fragile-x in x-linked mental retardation. The Egyptian Journal of Medical Human Genetics،Vol. 9, no. 2, pp.237-248.
https://search.emarefa.net/detail/BIM-105860
Modern Language Association (MLA)
al-Sobky, Izzat S.…[et al.]. Frequency of fragile-x in x-linked mental retardation. The Egyptian Journal of Medical Human Genetics Vol. 9, no. 2 (Nov. 2008), pp.237-248.
https://search.emarefa.net/detail/BIM-105860
American Medical Association (AMA)
al-Sobky, Izzat S.& Abu al-Ula, Suhayr& Tawfiq, Maha A.& Muhammad, Wafa M.. Frequency of fragile-x in x-linked mental retardation. The Egyptian Journal of Medical Human Genetics. 2008. Vol. 9, no. 2, pp.237-248.
https://search.emarefa.net/detail/BIM-105860
Data Type
Journal Articles
Language
English
Notes
Includes bibliographical references : p. 247-248
Record ID
BIM-105860