Novel Mutations in the Amyloid Precursor Protein Gene within Moroccan Patients with Alzheimer's Disease

In Morocco, Alzheimer's disease (AD) affects almost 30,000 individuals, and this number could increase to 75,000 by 2020. To our knowledge, the genes predisposing individuals to AD and predicting disease incidence remain elusive. In this study, we aimed to evaluate the genetic contribution of mutations in the amyloid precursor protein (APP) gene exons 16 and 17 to familial and sporadic AD cases. Seventeen sporadic cases and eight family cases were seen at the memory clinic of the University of Casablanca Neurology Department. These patients underwent standard somatic neurological examination, cognitive function assessment, brain imaging, and laboratory tests. Direct sequencing of exons 16 and 17 of the APP gene was performed on genomic DNA of AD patients. In this original Moroccan study, we identified seven novel frameshift mutations in exons 16 and 17 of the APP gene. Interestingly, only one novel splice mutation was detected in a family case. There is a strong correlation between clinical symptoms and genetic factors in Moroccan patients with a family history of AD. Therefore, mutations in APP gene exons 16 and 17 may eventually become genetic markers for AD predisposition.     

Influence of genetics and non-genetic factors on acenocoumarol maintenance dose requirement in Moroccan patients

What is known and Objective: Coumarin derivatives such as acenocoumarol represent the therapy of choice for the long‐term treatment and prevention of thromboembolic diseases. Many genetic, clinical and demographic factors have been shown to influence the anticoagulant dosage. Our aim was to investigate the contribution of genetic and non‐genetic factors to variability in response to acenocoumarol in Moroccan patients. Methods: Our study included 114 adult Moroccan patients, receiving long‐term acenocoumarol therapy for various indications. Tests for VKORC1 ‐1639G>A promoter polymorphism (rs9923231), CYP2C9*2 rs1799853, CYP2C9*3 rs1057910, and CYP4F2 rs2108622 alleles were undertaken using Taq Man^® Pre‐Developed Assay Reagents for allelic discrimination. The statistical analysis was performed using the SAS V9 statistical package. Results and Discussion: Genotyping showed that the allele frequencies for the SNPs studied were no different to those found in Caucasians population. A significant association was observed between the weekly maintenance dose and the VKORC1 (P = 0·0027) and CYP2C9 variant genotypes (P = 0·0082). A final multivariate regression model that included the target International Normalized Ratio, VKORC1 and CYP2C9 genotypes explained 36·2% of the overall interindividual variability in acenocoumarol dose requirement. What is new and Conclusion: Our study shows large interindividual variability in acenocoumarol maintenance dose requirement in our population. VKORC1 and CYP2C9 variants significantly affected acenocoumarol dose, in‐line with results in other populations. For the Moroccan population, the SNPs that have the largest effect on acecoumarol dose are CYP2C9 rs1799853, CYP2C9 rs1057910 and VKORC1 rs9923231.     

Synergistic effect of MTHFR C677T and F2 G20210A polymorphisms on ischemic stroke

The predisposition to stroke might involve interactive effects among variants in several genes.We tested this hypothesis by examining the influence of polymorphisms in methylenetetrahydrofolate reductase（MTHFR）（C677T） and prothrombin（F2）（G20210A） as risk factors for stroke in Morocco.The polymerase chain reaction-restriction fragment length polymorphism methods were used to analyze DNA from 91 stroke patients and 182 controls.Association between the two polymorphisms and the risk of stroke was estimated by four-level models for the analysis of genetic interaction.Neither the MTHFR 677TT nor the F2 20210GA genotype showed any significant association compared to the MTHFR CC and F2 GG genotypes,respectively.An interactive effect between the MTHFR 677TT and F2 20210GA polymorphisms showed an increased risk of stroke.The odds ratios,in univariate and multivariate analysis,for the combined polymorphisms were 4.99（95% CI,1.75–14.2,P = 0.001） and 5.29（95% CI,1.63–17.1,P = 0.005）,respectively.     

First Study of the C2491t Nonsense Mutation Frequency in Moroccan Healthy Population

The mutation FV Leiden (G1691A) is the most common mutation worldwide with a variable allelic frequency between countries. More frequent in the European and Caucasian populations and rare or absent in African native population, the FVL was studied in the Moroccan population (They-They et al. Ann Hum Biol 37(6):767–777, 2010) and is totally absent as reported previously by (Mathonnet et al. Thromb Haemost 88(6):1073–1074, 2002). Here, another mutation in FV (Q773Term) was detected in a Moroccan patient, which took our interest for this study and establishes the first epidemiological database for future associated studies concerning neurovascular diseases.     

Prenatal Diagnosis of BMD in Morocco: Evolution and Limits

The muscular dystrophy is a group of inherited disorders characterized in the most of cases by progressive muscle weakness. The best known are X-linked disorder Duchenne muscular dystrophy (DMD) and Becker muscular dystrophy (BMD). BMD is a milder form of the disease with a later age of onset and a slower clinical progression. The DMD gene, located on Xp21, is the largest human gene in the human genome (2.3 Mb). DMD gene consists of 79 exons and codes for dystrophin protein. A 9-year-old boy, who experienced symptoms of the disease, was admitted to the Casablanca University Children’s Hospital. The patient, with no known family history of significant muscle disease, was first examined at 4 years of age because of walking difficulties and a limited hands force. Blood tests revealed elevated serum levels of creatine kinase (7.60 U/L). The electromyogram showed myopathic changes, consisting of polyphasic potentials, and the muscular biopsy revealed dystrophic aspect. Analysis of the dystrophin-encoding gene by PCR deletion analysis of the dystrophin gene was performed by multiplex PCR primer sets of Chamberlain and Beggs. The analysis showed a deletion of exons 45 to 49. Mother genetic testing showed the heterozygosis deletion.     

Methylenehydrofolate reductase (C677T) polymorphism and large artery ischemic stroke subtypes

They‐They TP, Nadifi S, Rafai MA, Battas O, Slassi I. Methylenehydrofolate reductase (C677T) polymorphism and large artery ischemic stroke subtypes.
Acta Neurol Scand: 2011: 123: 105–110.
© 2010 John Wiley & Sons A/S. Background – The role for the methylenetetrahydrofolate reductase C677T gene variants in the risk of ischemic stroke is controversial. Method – This first case–control study including 91 cases affected by ischemic stroke and 182 controls matched for age, sex, and same area was conducted in Casablanca, Morocco. Allele and genotype frequency were characterized by using PCR followed by HinfI enzymatic digestion. Results – We found no statistic association of T allele carriers genetic factors with stroke; odds ratio, 1.1; 95% confidence interval (CI), 0.59–2.04, P = 0.303. The results shown significant association of T allele carriers genetic factors with atherothrombotic subtype stroke (n = 42); odds ratio, 2.1; 95% CI: 1.17–3.8; P = 0.012, and adjusted odds ratio of 6.5; 95% CI: 1.86–23.1, P = 0.003, for TT genotype variant compared with CC wild genotype. Conclusion – We suggested that MTHFR C677T variant may be a determinant of atherothrombotic event of ischemic stroke in Morocco.     

Étude de la corrélation génotype–phénotype dans l’amyotrophie spinale infantile (ASI) dans une famille marocaine

Spinal muscular atrophy (SMA) is an autosomal recessive disorder with a highly variable clinical course and prognosis. We report on the cases of three siblings with SMA. The weakness muscular observes at three siblings but more earlier and severe to the index case with a fast evolution towards respiratory distress syndrome resulting in its death at 5 years. The homozygous deletions of exons 7 and 8 of the telomeric SMN gene were found in all three siblings. No child showed deletion of NAIP gene. Muscular weakness and respiratory distress severity however were different among the siblings. The index patient died at the age of 5 because of respiratory insufficiency. Several molecular mechanisms may be involved in such phenotypic variability. The PCR-RFLP method allows to confirm clinical diagnosis of SMA in children, while avoiding more invasive methods such as EMG and muscular biopsy. However, this diagnostic tool does not allow yet the distinction between different clinical forms of SMA.     

Influence of mutation of the HFE gene on the progression of chronic viral hepatitis B and C in Moroccan patients

The implication of hemochromatosis (HFE) gene mutations in chronic viral hepatitis remains controversial. The aim of the present study was to measure the frequencies of the common HFE gene mutations in Moroccan subjects with chronic viral hepatitis B and C and to assess their influence on the progression of liver disease. H63D and C282Y mutations were screened by the polymerase chain reaction followed by restriction fragment length polymorphism analysis in 170 chronic hepatitis B patients, 168 chronic hepatitis C patients, and 200 healthy controls. A very small proportion of patients infected with hepatitis B virus (HBV) or hepatitis C virus (HCV; 1.8% and none, respectively) were heterozygous for the C282Y mutation, that is, rates not statistically different from those observed in healthy control (2%, P > 0.05). Similarly, the frequency of the H63D allele was not significantly different between HBV (13.8%) or HCV (14.3%) patients and controls (13.5%, P > 0.05). Multivariate analysis showed that carriers of the H63D mutation infected with HBV are at higher risk to progress towards an advanced liver disease when compared with patients infected with HBV with wild‐type (OR = 2.45, 95% CI = 1.07–5.58). In contrast, no association between HFE mutated HCV‐infected patients and an increased risk of disease progression was found (OR = 1.24, 95% CI = 0.61–2.50, P = 0.547). In conclusion, in Morocco the frequency of the HFE C282Y allele is very low and H63D mutation carriage occurs in almost 14% of the patients, a rate similar in chronic hepatitis patients and healthy controls. In the case of chronic hepatitis B, the carriage of the H63D variant represents a risk factor of evolution towards a more active disease. J. Med. Virol. 83:2096–2102, 2011. © 2011 Wiley Periodicals, Inc.     

c.1643_1644delTG XPC mutation is more frequent in Moroccan patients with xeroderma pigmentosum

Xeroderma pigmentosum is a rare autosomal recessive disease characterized by hypersensitivity to UV light which is due to alterations of the nucleotide excision repair pathway. Eight genes (XPA to XPG and XPV) are responsible for the disease. Among them, the XPC gene is known to be the most mutated in Mediterranean patients. The aim of this study was to determine the frequency of the most common XPC mutation and describe the clinical features of Moroccan patients with xeroderma pigmentosum. Twenty four patients belonging to 21 unrelated Moroccan families and 58 healthy subjects were investigated. After clinical examination, the screening for the c.1643_1644delTG (p.Val548AlafsX25) mutation in the XPC gene was performed by PCR and automated sequencing of exon 9 in all patients and controls. The molecular analysis showed that among the 24 patients, 17 were homozygous for the c.1643_1644delTG mutation and all their tested parents were heterozygous, whereas the others (7 patients) did not carry the mutation. The frequency of this mutation was estimated to be 76.19 % (16/21 families). None of the 58 healthy individuals carried this mutation. In addition, clinical investigation showed that the majority of the patients bearing this mutation have the same clinical features. Our results revealed that the p.Val548AlafsX25 mutation is the major cause (76.19 %) of xeroderma pigmentosum in Moroccan families. This would have an important impact on improving management of patients and their relatives.