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Hila L.,Laboratoire Of Genetique Humaine | Tebourbi H.,Laboratoire Of Genetique Humaine | Abeid L.,Laboratoire Of Genetique Humaine | Rejeb I.,Laboratoire Of Genetique Humaine | Chaabouni H.,Service des Maladies Congenitales et Hereditaires EPS Charles Nicolle
Biochemical Genetics | Year: 2010

Copy number changes of subtelomeric regions are a common cause of mental retardation, occurring in approximately 5% of mentally retarded patients. New molecular techniques allow the identification of subtelomeric microduplications. We report a Tunisian family of three sisters with moderate mental retardation, facial dysmorphism, cardiopathy, and bilateral clinodactyly of the third and fourth toes, explored by MLPA, showing the same associated microduplications, 15q and Xq, without a concurrent deletion. © 2010 Springer Science+Business Media, LLC.

Kharrat M.,Laboratoire Of Genetique Humaine | Trabelsi S.,Laboratoire Of Genetique Humaine | Chaabouni M.,Laboratoire Of Genetique Humaine | Maazoul F.,Laboratoire Of Genetique Humaine | And 7 more authors.
Clinical Genetics | Year: 2010

Steroid 11β-hydroxylase deficiency is the second most common cause of congenital adrenal hyperplasia, resulting in virilization, glucocorticoid deficiency and hypertension. The 11β-hydroxylase enzyme is encoded by the CYP11B1 gene and mutations in this gene are responsible for this disease. The aim of this study was to characterize mutations in the CYP11B1 gene and to determine their frequencies in a cohort of Tunisian patients. The molecular genetic analysis was performed by direct nucleotide sequencing of the CYP11B1 gene in 15 unrelated Tunisian patients suffering from classical 11β-hydroxylase deficiency. Only two mutations were detected in homozygous state in the CYP11B1 gene of all patients, the p.Q356X in exon 6 (26.6%) and the novel p.G379V in exon 7 with large prevalence (73.3%). This is the first report of screening for mutations of CYP11B1 gene in the Tunisian population and even in the Arab population. © 2010 John Wiley & Sons A/S.

Kharrat M.,Laboratoire Of Genetique Humaine | Riahi A.,Laboratoire Of Genetique Humaine | Maazoul F.,Laboratoire Of Genetique Humaine | M'rad R.,Laboratoire Of Genetique Humaine | Chaabouni H.,Laboratoire Of Genetique Humaine
Diagnostic Molecular Pathology | Year: 2011

Earlier we had reported a large prevalence of the Q318X mutation in the CYP21A2 gene with 35.3% in Tunisian patients with a classical form of 21-hydroxylase deficiency, in contrast with 0.5% to 13.8% as described in other populations. Here we present the analysis of the Q318X mutation in a healthy Tunisian population. We screened 136 individuals by the polymerase chain reaction (PCR)/random fragment length polymorphism method, which was confirmed by direct sequencing. Surprisingly, 17 Q318X carriers were identified, for a carrier frequency of 12.5% (95% confidence interval: 7.86-19.20). To explain this unexpectedly high rate we suggest that the haplotype with Q318X mutation and duplicated CYP21A2 gene could be very frequent in the Tunisian population. To test our hypothesis, we used 2 different quantitative PCR methods, that is, multiplex ligation-dependent probe amplification and real-time PCR. The molecular studies showed the presence of a duplicated CYP21A2 gene in all 17 heterozygous Q318X mutation carriers. In addition, both quantitative PCR methods used in this study represent a sensitive and useful approach to detecting copy number variations of the CYP21A2 gene. We have identified a very high frequency of carriers with duplicated CYP21A2 gene haplotype in a healthy Tunisian population. This finding complicates the molecular diagnosis of 21-hydroxylase deficiency and we recommend that, whenever a Q318X is identified, the structure of the CYP21A2 region should be determined to discriminate between the severe Q318X mutation and the normal Q318X variant. Copyright © 2011 by Lippincott Williams & Wilkins.

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