Consanguinity and Associated Conditions Prevalence in Fragile X Syndrome Cases in Eastern Region in Saudi Arabia

Abstract

Fragile X Syndrome (FXS) is an X-linked genetic defect and the leading monogenic cause of inheritable Intellectual Disability (ID), which is caused by an abnormal expansion in trinucleotides CCG repeats in the Fragile X Mental Retardation 1 (FMR1) gene. Consanguinity has been reported to involve a high risk of inheriting this genetic disorder, while consanguineous marriage in Saudi Arabia is estaimated at 56%. This study aimed to examine the relationship between the FXS prevalence, the prevalence of the FXS associated conditions, and parental consanguinity in the FXS patients in the Eastern Region in Saudi Arabia. We examined 17 patients with positive alteration in FMR1 gene in hospitals in Dammam and Dhahran districts by extracting data from the patients’ medical records. The study variables were as follows: level of ID, FXS associated conditions, parental consanguinity, and the number of FXS siblings in the family. We used descriptive statistics to characterize the case relations, and prevalence was expressed in percentages.Data on patients were described in gender (16 males, 1 female), and age was distributed from 1-21 in five aged range categories. 15 cases with FXS and two premutations with ID and associated conditions frequency resulted. The two were excluded from ID and associated condition frequency, along with the female patient with FXS who had no associated condition. Consanguinity was found in 13/17 cases (76.47%), in which 2 cases were premutations, and 7 out of nine families included in this study were consanguineous, with four families having FXS siblings. The associated conditions were found in 14 FXS cases; four cases were observed with hyperactivity (26.57%), two cases with ASD, two with speech delay, two cases with aggressive behavior (14.3%), and one case with Hypertonia, abnormal laughter, epilepsy, and reckless behavior (7.14%). The results of this study suggest a high effect of consanguineous parenting on FXS prevalence. The test for associated conditions showed direct relation with increasing rates in FXS male cases. These findings contradicted with the results of previous studies in Saudi Arabia and other studies around the world. Preselection-based patients on positive cytogenetic test result are likely to have effected the results of this study. Also, the results may be affected by the small number of study participants.

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