الفهرس | Only 14 pages are availabe for public view |
Abstract Mental retardation is a genetic disorder manifested in significantly below average overall intellectual functioning and deficit in adaptive behavior. Fragile X syndrome is the most commonly inherited form of mental retardation which affects the child and potentially the mother and other family members. The multiple manifestations in different age groups have led to fragile X syndrome being designated as one in the spectrum of FMR1related disorders. Variations in FMR1 CGG repeat size is a useful biomarker of various types of risk that affect parents ,as it defines differences between ’’healthy’’ and ’’ affected’’ and between full mutation and premutation carriers. It is assumed that FMR-1 protein is essential for the normal development of central nervous system which important for learning and memory, and the loss or reduction in FMR-1 transcription is the critical event leading to mental retardation in the people fragile X syndrome; including intellectual disability ,cognitive impairments and behavioral problems. Our study aimed to study FMR1 gene in 50 boys who was chosen after IQ examination using Stanford Binet intelligence test 4th edition and they had IQ score <70, their ages ranged between 3-16 years, with exclusion of patients with known genetic etiology including well defined syndromes as Down syndrome and metabolic causes or history of prenatal, natal and postnatal insults, severe or profound mental retardation (IQ<20). All patients were subjected to the following (Full history, full clinical examination, anthropometric measurements, routine investigations if needed, assessment of IQ using Stanford Binet intelligence test 4th edition and molecular study of FMR1 gene. Molecular studies: a) DNA extraction from blood samples. b) Polymerase chain reaction (PCR) for FMR1 gene. c) Gel electrophoresis for amplified gene products on agarose gel 2%. Results of our study showed that: the prevalence of FXS full mutation was (6%) and prevalence of FXS premutation was (8%). Most of patients (52%) were in late childhood period (6ys <12ys), (76%) had family history of first degree relatives,(24%) had family history of second degree relatives, consanguinity presented in (14%) with no significant (P-value 0.64) As regards craniofacial abnormalities of all patients there were (46%) had prominent forehead, (30%) had long face, (70%) had high arched palate, (52%) had large prominent ear. Neuropsychatric problems (64%) had speech problem, (50%) had hyperactivity, (38%) had autistic features and (20%) had epilepsy. Genital examination one patient 2% had macroorchodism. According to IQ of our patients (54%) had moderate mental retardation with IQ (51-36);(66.7% of full mutation patients and 50% of premutation patients) ,46% had mild mental retardation with IQ (52-68); 33.3% of full mutation patients and 50% of premutation patients. As regards fragile X features (long face, large prominent ear, hyperextensible joint, macroorchidism, hyperactivity, autistic features in form of repetitive speech and lack of attention , speech problem) In full mutation patients (long face, large prominent ear, hyperextensible joint presented in 66.7% of each, 33.3% had macroorchidism (p-value < 0.0001). , hyperactivity presented in 100%, autistic features presented in 66.7% and speech problem presented in 100% of patients. |