Genetic diseases in the Tunisian population

Abstract

Tunisia is one of the North African countries, geographically situated in a central position at the crossroad between Africa and Europe. The demographic features of the Tunisian population include among others high rates of consanguinity. We report, here on the spectrum of genetic diseases in Tunisia. The review of the literature, including other available information (gray literature) showed that there are at least 346 genetic disorders for which cases have been identified in the Tunisian population. Among these, 62.9% are autosomal recessive, 23% autosomal dominant, 5.4% X-linked, and the remaining are of Y-linked, mitochondrial, and unknown mode of transmission. Fifty percent of the reported conditions in this study are caused by at least one mutation. For autosomal recessive diseases, most of the mutations were identified at homozygous state among the affected individuals. Part of the mutations was the result of a founder effect; these are the consequences of the high rate of consanguinity. The congenital malformations, diseases of the nervous system and metabolic disorders are the major groups of genetic diseases affecting the Tunisian population. The large spectrum of diseases and their relatively high frequency could be explained by the high degree of inbreeding and the presence of multiple mutations, either allelic or in different genes. This is due to the richness of the genetic background of the studied population. A multidisciplinary approach is essential to develop adequate preventive programmes adapted to the social, cultural, and economic context.

The Experience of a Tunisian Referral Centre in Prenatal Diagnosis of <b><i>Xeroderma pigmentosum</i></b>

“…According to our experience in rare diseases in Tunisia, in some cases, 2 or more diseases cosegregate within the same family [9]. Even if this event is rare, the genetic counsellor should be aware of this possibility, in order to avoid the very unlikely case that the foetus is excluded of having the screened mutation but bares another mutation which is responsible for another disease.…”

Macrozoospermia: screening for the homozygous c.144delC mutation in AURKC gene in infertile men and estimation of its heterozygosity frequency in the Tunisian population

“…In Tunisia, as in many Arab countries, there is a high preference for unions between relatives (first cousin marriages are the most represented). The rate of consanguinity is estimated to be more than 32 % and may reach 60 % in rural areas, which highly increases the risk of recessively inherited disorders [27]. Otherwise, 10 patients (41.7 %) were issued from nonconsanguineous parents suggesting the relative frequency of this mutation in the general population.…”

The Moroccan Genetic Disease Database (MGDD): a database for DNA variations related to inherited disorders and disease susceptibility

“…9 This is similar to the situation in Tunisia, where frequencies of autosomal recessive and dominant disorders were 62.9% and 22.9%, respectively. 17 The disease classification reveals that endocrine, nutritional and metabolic diseases, congenital malformations and neurodegenerative diseases are the major categories of Mendelian disorders in the Moroccan population, with similar prevalence as in the Tunisian population. 17 We plan to collect and add new mutation data from diagnostic services and research laboratories to our database continuously.…”

“…17 The disease classification reveals that endocrine, nutritional and metabolic diseases, congenital malformations and neurodegenerative diseases are the major categories of Mendelian disorders in the Moroccan population, with similar prevalence as in the Tunisian population. 17 We plan to collect and add new mutation data from diagnostic services and research laboratories to our database continuously. MGDD encourages the human genetic research community and clinicians to submit their genetic data via dedicated web forms.…”