ABSTRACT
Introduction: Triple-A syndrome (Triple-A) is an autosomal recessive disorder characterized by alacrimia, achalasia, and adrenal insufficiency. Several variants on the AAAS gene have been described, and some variants are clustered in particular geographical areas, such as the c.1331+1G>A variant which is very frequent in North Africa. Here, we describe the genetic features of Triple-A in a series of unrelated families from Morocco. Methods: Screening for the AAAS c.1331+1G>A variant was performed by direct sequencing or by PCR-RFLP. Haplotype analysis using Single Tandem Repeat (STR) markers flanking AAAS gene was performed in order to evaluate the founder effect and estimate the age of the c.1331+1G>A variant. Results: Seven unrelated families with ten individuals clinically diagnosed with Triple-A were evaluated for sequence variations in the AAAS gene. The median age at diagnosis was 3 years, with a range between 2 and 11 years. Molecular analysis revealed that all patients were homozygous for the c.1331+1G>A variant. This variant was not found in 200 healthy controls, indicating that carriers are very rare in the general Moroccan population. Subsequently, STR marker analysis revealed a founder effect and that the most recent common ancestor of Triple-A patients in Morocco would have lived 125 years ago. Conclusion: This is the largest series of Triple-A in Morocco. The same AAAS c.1331+1G>A variant was found in all patients, suggesting a founder effect in Morocco which was subsequently confirmed by microsatellite marker analysis. Therefore, this variant should be systematically investigated to diagnose Triple-A in Morocco.
ABSTRACT
Familial Mediterranean Fever (FMF, MIM 249100) is an autosomal recessive disease mainly affecting patients of the Mediterranean basin. It is an autoinflammatory periodic disorder characterised by recurrent episodes of fever and abdominal pain, synovitis and pleuritis. FMF is caused by mutations in the Mediterranean Fever (MEFV) gene located on chromosome 16p13.3. Several mutations in the MEFV gene have been characterised in different populations. However, very little is known about mutations in the MEFV gene in patients with Moroccan origin. The aim of this study is to determine the clinical components of FMF and characterise mutations in the MEFV gene in Moroccan patients. The study was carried out on 120 unrelated Moroccan patients referred to the department of medical genetics in Rabat for suspicious FMF over a period of 10 years. Patients were screened for the most common MEFV mutations by direct sequencing of exons 2 and 10. Of the 120 unrelated patients investigated, 56 patients (47%) were carriers of one or two MEFV mutations, and 64 patients (53%) had no detected mutations. Of those with mutations, 24 were homozygous (44%), 13 were compound heterozygotes (24%), and 19 patients had only 1 identifiable mutation (32%). The most frequent mutation in Moroccan patients is M694V (47%), followed by M694I (32%), A744S (6.5%), M680L (4%), M694del (2%) and E148Q (6.5%). The R761H, K695R and I692del mutations were rarely encountered (less than 1%). The V726A mutation was not found in our study. Our data represent the first report of MEFV gene mutations causing FMF in Moroccans patients. The M694V and M694I mutations are the most common mutations found in MEFV gene in Moroccan population; while the most common mutation in Arabs from the Middle-East region, the V726A, was not found in our population.
