Association of the OPRM1 and COMT genes' polymorphisms with the efficacy of morphine in Tunisian cancer patients: Impact of the high genetic heterogeneity in Tunisia?

BACKGROUND: Genetic causes for inter-individual variability response to opioids are clinical difficulties for treatment efficiency. The aim of the present study was to investigate the possible association of opioid treatment outcome with single nucleotide polymorphisms (SNPs) in the mµ opioid receptor (OPRM1) and catechol-o-methyltransferase (COMT) genes, in Tunisian cancer pain patients. METHODS: We genotyped one hundred and twenty-nine cancer patients treated with different doses of morphine for 3 SNPs in OPRM1 gene (rs17174629, rs1799972 and rs1799971) and one in the COMT gene (rs4680). Associations between dose (continuous), dose escalation (yes/no) and SNP or haplotypes were investigated. RESULTS: Unlike other studies on Caucasian and Chinese populations, no significant association were found between the 4 polymorphisms screened and the dose of morphine needed for pain relief. CONCLUSION: This result can be explained by the genetic heterogeneity and cosmopolitan areas of our Tunisian patients compared to the others homogenous population.

Genetics of low spinal muscular atrophy carrier frequency in sub-Saharan Africa.

OBJECTIVE: Spinal muscular atrophy (SMA) is one of the most common severe hereditary diseases of infancy and early childhood in North America, Europe, and Asia. SMA is usually caused by deletions of the survival motor neuron 1 (SMN1) gene. A closely related gene, SMN2, modifies the disease severity. SMA carriers have only 1 copy of SMN1 and are relatively common (1 in 30-50) in populations of European and Asian descent. SMN copy numbers and SMA carrier frequencies have not been reliably estimated in Malians and other sub-Saharan Africans. METHODS: We used a quantitative polymerase chain reaction assay to determine SMN1 and SMN2 copy numbers in 628 Malians, 120 Nigerians, and 120 Kenyans. We also explored possible mechanisms for SMN1 and SMN2 copy number differences in Malians, and investigated their effects on SMN mRNA and protein levels. RESULTS: The SMA carrier frequency in Malians is 1 in 209, lower than in Eurasians. Malians and other sub-Saharan Africans are more likely to have ≥3 copies of SMN1 than Eurasians, and more likely to lack SMN2 than Europeans. There was no evidence of gene conversion, gene locus duplication, or natural selection from malaria resistance to account for the higher SMN1 copy numbers in Malians. High SMN1 copy numbers were not associated with increased SMN mRNA or protein levels in human cell lines. INTERPRETATION: SMA carrier frequencies are much lower in sub-Saharan Africans than in Eurasians. This finding is important to consider in SMA genetic counseling in individuals with black African ancestry.

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

PURPOSE: Macrozoospermia is a rare condition of male infertility characterized by the presence of close to 100 % large-headed multiflagellar spermatozoa. The homozygous mutation (c.144delC) in aurora kinase C gene (AURKC) has been identified as the most frequent mutation causing macrozoospermia in North African patients. The aim of this study was to evaluate the prevalence of this condition in Tunisia and estimate the frequency of c.144delC mutation among infertile and control populations. METHODS: Sequencing c.144delC mutation was carried out in 33 macrozoospermic patients among 6652 infertile men. Minisequencing of exon3 was performed in 250 unrelated control individuals to estimate the frequency of c.144delC heterozygosity. RESULTS: More than 80 % of macrozoospermic patients were c.144delC homozygous. The prevalence of homozygous c.144delC was 0.4 % among infertile men (27/6652). The frequency of heterozygosity was 0.4 % among controls (1/250). Surprisingly, it is five times less common than established in the general population of North Africa (2 %) or in the Moroccan population (1.7 %). CONCLUSIONS: We show that this mutation is relatively less frequent in the Tunisian population than in other Maghrebian populations. The occurrence of homozygous mutation among infertile men can be attributed to the high rate of consanguinity and its impact on the expression of this autosomal recessive male infertility disorder rather than a high frequency of heterozygous carriers among the general population. This highlights the importance of the molecular analysis of AURKC mutations for infertile men with high percentage of large-headed multiflagellar spermatozoa in order to limit unnecessary in vitro fertilization attempts for them.

Multiplex Minisequencing of the HBB Gene: A Rapid Strategy to Confirm the Most Frequent ß-Thalassemia Mutations in the Tunisian Population.

The ß hemoglobinopathies [ß-thalassemia (ß-thal) and structural hemoglobin (Hb) variants such as Hb S (HBB: c.20A > T) and Hb E (HBB: c.79G > A)] are among the most common inherited diseases worldwide. In Tunisia, due to the high prevalence of consanguineous marriages, the recurrent risk of this disease is high. The average prevalence of hemoglobinopathies is 4.48%, reaching 12.50% in some focus regions. The molecular investigations on thalassemia contributed to establishing the spectrum of mutations in the Tunisian population. The total number of HBB gene mutations identified was 24. The two most frequent mutations, codon 39 (C > T) (HBB: c.118C > T) and IVS-I-110 (G > A) (HBB: c.93-21G > A) accounted for 70.0% of the total encountered ß-thal cases. These two mutations together with IVS-I-2 (T > G) (HBB: c.92 + 2T > G) and the Hb S variant account for more than 90.0% of all HBB genetic variants in Tunisia. Thus, developing rapid, inexpensive and reliable mutation-specific molecular diagnostic assays targeting our Tunisian populations is our aim to facilitate routine detection of hemoglobinopathies. In this report, we describe the successful application of the multiplex minisequencing assay as an alternative strategy for genetic diagnosis of HBB gene disorders in Tunisia.

A Systematic Review of Chronic Diseases and Their Prevalence Among the Population of Northern Borders Province (NBP) in Saudi Arabia.

Estimation of the prevalence of chronic conditions is pivotal to effective healthcare planning and management. Therefore, our objective was to systemically review previous literature about the prevalence of chronic diseases among residents of Northern Borders Province (NBP) in Saudi Arabia. The electronic search has been done using scientific databases (PubMed, Ebsco, SciFinder, and Web of Science) and search engines up to September 2021. The following main key terms: chronic disease OR chronic conditions AND prevalence AND Northern Borders Province OR Northern Borders AND Saudi Arabia were applied. Other related terms with a more specific search were done with names of the main cities in the province and the most common diseases in Saudi Arabia. Duplicates were removed electronically by Endnote and manually. Extracted data were tabulated in the literature matrix. The risk of bias and quality of included studies were assessed using the "Strengthening the Reporting of Observational Studies in Epidemiology" (STROBE) checklist. Out of 63 observational studies that were assessed for eligibility, 21 observational studies were included to synthesize the evidence. These studies were conducted on Arar (n=16), Turaif (n=2), and Rafha (n=1), while the remaining were national studies in which NBP was one of the included regions (n=2). The most frequently studied diseases were diabetes (4 records), psychological diseases (4 records), and obesity (3 records). The most prevalent disease was gastroesophageal reflux disease (GERD), with an estimated prevalence of 61% among adults in Arar city. In conclusion, although some research is conducted about chronic diseases somewhere in NBP, further studies are needed to study chronic diseases using a representative sample of the whole NBP population.

Molecular and biochemical characterization of Tunisian patients with glycogen storage disease type III.

Glycogen storage disease type III (GSD III) is an autosomal recessive inborn error of metabolism caused by mutations in the glycogen debranching enzyme amylo-1,6-glucosidase gene, which is located on chromosome 1p21.2. GSD III is characterized by the storage of structurally abnormal glycogen, termed limit dextrin, in both skeletal and cardiac muscle and/or liver, with great variability in resultant organ dysfunction. The spectrum of AGL gene mutations in GSD III patients depends on ethnic group. The most prevalent mutations have been reported in the North African Jewish population and in an isolate such as the Faroe Islands. Here, we present the molecular and biochemical analyses of 22 Tunisian GSD III patients. Molecular analysis revealed three novel mutations: nonsense (Tyr1148X) and two deletions (3033_3036del AATT and 3216_3217del GA) and five known mutations: three nonsense (R864X, W1327X and W255X), a missense (R524H) and an acceptor splice-site mutation (IVS32-12A>G). Each mutation is associated to a specific haplotype. This is the first report of screening for mutations of AGL gene in the Tunisian population.

Two novel CYP11B1 mutations in congenital adrenal hyperplasia due to steroid 11ß hydroxylase deficiency in a Tunisian family.

Steroid 11ß hydroxylase deficiency (11ß-OHD) (OMIM # 202010) is the second most common form of congenital adrenal hyperplasia (CAH), accounting for 5-8% of all cases. It is an autosomal recessive enzyme defect impairing the biosynthesis of cortisol. The CYP11B1 gene encoding this enzyme is located on chromosome 8q22, approximately 40kb from the highly homologous CYP11B2 gene encoding for the aldosterone synthase. Virilization and hypertension are the main clinical characteristics of this disease. In Tunisia, the incidence of 11ß-OHD appears higher due to a high rate of consanguinity (17.5% of congenital adrenal hyperplasia). The identical presentation of genital ambiguity (females) and pseudo-precocious puberty (males) can lead to misdiagnosis with 21 hydroxylase deficiency. The clinical hallmark of 11ß hydroxylase deficiency is variable, and biochemical identification of elevated precursor metabolites is not usually available. In order to clarify the underlying mechanism causing 11ß-OHD, we performed the molecular genetic analysis of the CYP11B1 gene in a female patient diagnosed as classical 11ß-OHD. The nucleotide sequence of the patient's CYP11B1 revealed two novel mutations in exon 4: a missense mutation that converts codon AGT (serine) to ATT (isoleucine) (c.650G>T; p.S217I) combined with an insertion of a thymine at the c.652-653 position (c.652_653insT). This insertion leads to a reading frame shift, multiple incorrect codons, and a premature stop in codon 258, that drastically affects normal protein function leading to a severe phenotype with ambiguous genitalia of congenital adrenal hyperplasia due to 11ß hydroxylase deficiency.

Familial early-onset diabetes is not a typical MODY in several Tunisian patients.

BACKGROUND: MODY (Maturity-onset diabetes of the young), a dominantly inherited form of early-onset diabetes, is clinically and genetically heterogeneous with more than ten genetic subtypes described worldwide. AIM: To evaluate the possible existence of MODY in 12 young diabetic Tunisian patients by searching for mutations in the most prevalent MODY genes. METHODS: Twelve patients with diabetes in 2-to-3 generations, all diagnosed before age 31, were screened for mutations and deletions in HNF1A, HNF4A, INS, IPF1, NEUROD1 and GCK genes by Sanger sequencing and by Multiplex ligation-dependent probe amplification assay. RESULTS: The patients had no evidence of autoimmunity and a mean age at diabetes diagnosis of 25.66 ± 3.96 years with severe overt diabetes (fasting glycaemia: 10.91 ± 3.55 mmol/ l; HbA1c: 10.46 ± 3.31 %). Two subjects were initially treated with insulin. On the ten initially treated with OHA or on diet, eight converted to insulin therapy (within 3 months to 20 years). Molecular analysis showed only one missense HNF4A mutation (I453V) in one family. No mutations in the studied genes were detected in the other patients. CONCLUSION: A molecular defect in known MODY genes has been excluded in 11 patients with early-onset diabetes suggesting that other genetic causes may explain diabetes in these families. In such cases, new generation sequencing approaches may be well appropriate to identify specific molecular etiologies from extended families and to establish a strategy of molecular diagnostic of MODY in Tunisia.

Frequency of HNF4A-P.I463V Variant in the Tunisian North-African Population and Its Relation with Diabetes Mellitus.

BACKGROUND: HNF4A-p.I463Vvariant, reported previously in two distinct families suspected of MODY-1, is assessed in this report to determine whether it is a mutation or a polymorphism (frequency >1%). METHODS: 200 Tunisian healthy people were screened for the presence of HNF4A-p.I463V variant, using RFLP-PCR technique and sequencing. Then, the frequency of this variant was estimated in the Tunisian population and compared to other populations registered in genetic databases. We also performed in-silico analysis using PolyPhen2 and Mutation T@sting softwares to assess the probable effect of HNF4A-p.I463V variant. RESULTS: HNF4A-p.I463V had a rare frequency in different populations and was found in 3 control subjects (1.5%) of the studied population. PolyPhen2 predicted that it is a polymorphism, whereas mutation T@sting suggested a probably affected mutant protein. CONCLUSION: HNF4A-p.I463V has a relatively high frequency (>1%) in our control cohort. It is also present in different ethnicities and in- silico analysis showed conflicting results. For these reasons, HNF4A-p.I463V should not be considered as a mutation responsible for MODY-1.

Genetic study in a tunisian family revealed IVS1+1G>A mutation in the CHM gene.

Choroideremia is a rare X-linked recessive, hereditary retinal pigment epithelial dystrophy, characterized by night blindness and progressive constriction of the visual fields leading to blindness in young adulthood. In this study, we reported three cases of choroideremia belonging to a Tunisian family. Patients complained of vision loss and night blindness. Fundus examination revealed diffused chorioretenal atrophy. In all cases, there was a visual field constriction and an undetectable electroretinography. Direct sequencing of the CHM gene detected a guanine to adenine transition (G>A) into the donor splice site of intron 1 leads to aberrantly spliced mRNA producing a premature stop codon and therefore functional loss of the CHM gene product, REP-1. The diagnosis should be considered in patients with a suitable family history and fundus findings.

Correlation of SMN2, NAIP, p44, H4F5 and Occludin genes copy number with spinal muscular atrophy phenotype in Tunisian patients.

OBJECTIVES: Spinal muscular atrophy (SMA) is an autosomal recessive neuromuscular disorder which is characterized by a high clinical variability with severe, intermediate, mild and adult forms. These forms are caused, in 95% of cases, by a homozygous deletion of exon 7 of SMN1 gene. Our purpose was the determination of a possible genotype-phenotype correlation between the copy number of SMN2, NAIP, p44, H4F5 and occludin genes localized in the same SMN1 region (5q13) and the severity of the disease in SMA Tunisian patients. PATIENTS AND METHODS: Twenty six patients affected by SMA were enrolled in our study. MLPA and QMPSF were used to measure copy numbers of these genes. RESULTS: We found that 31.3% of type I patients carried one copy of SMN2, while all patients of other forms had at least 2 copies. NAIP was absent in 87.5% of type I patients. Furthermore, all SMA type I patients had one copy of H4F5. No correlation was found for p44 and occludin genes. CONCLUSION: There is a close relationship between SMN2, NAIP and H4F5 gene copy number and SMA disease severity, which is compatible with the previous reports.