Absence of GATA4 Mutations in Moroccan Patients with Atrial Septal Defect (ASD) Provides Further Evidence of Limited Involvement of GATA4 in Major Congenital Heart Defects.

OBJECTIVE: Atrial septal defect (ASD) is one of the most common types of congenital heart disease (CHD). It is mainly caused by mutations of NK2 homeobox 5, GATA binding protein 4 (GATA4), and myosin heavy chain 6 in non-syndromic cases. This study aims to carry out, for the first time, the GATA4 mutation screening in a Moroccan population affected by ASD and compare the obtained mutation rate across populations. MATERIALS AND METHODS: A total of 33 patients were enrolled in this study. DNAs were extracted from peripheral blood samples, and we performed PCR-sequencing for GATA4 coding regions. Sequences were analyzed by sequence alignment and functional impact prediction tools. Mutation rate comparisons were performed by R software using the appropriate statistical tests. RESULTS: We detected 7 variants, but no pathogenic mutation was revealed, except for Asn352= that was assessed by human splicing finder algorithms to have a potential impairing effect on the splicing mechanism. Until proven by in vitro functional studies, the current pathogenic mutation rate in our cohort seems to be 0%. Statistical comparison with previous studies from all over the world shows no significant difference. Seemingly, comparison of previous GATA4 mutation rates among tetralogy of Fallot (TOF) populations shows no significant difference. CONCLUSION: The low rates of GATA4 mutations observed throughout ASD and TOF international populations may suggest a limited causality of GATA4 mutations in the main CHDs, which further confirms the co-involvement of additional genetic and/or environmental factors in the manifestation of these phenotypes.

GATA4 molecular screening and assessment of environmental risk factors in a Moroccan cohort with tetralogy of Fallot.

BACKGROUND: Tetralogy of Fallot (TOF) is the most common cyanotic congenital heart defect (CHD) with an incidence of 1/3600 live births. This disorder was associated with mutations in the transcription factors involved in cardiogenesis, like Nk2 homeobox5 (NKX2-5), GATA binding protein4 (GATA4) and T-BOX1 (TBX1). GATA4 contributes particularly to heart looping and differentiation of the second heart field. OBJECTIVES: The aim of this study was to screen a Moroccan cohort with tetralogy of Fallot for GATA4 mutations, and to assess environmental risk factors that could be involved in the occurrence of this disorder. METHODS: Thirty-one non-syndromic TOF patients, enrolled between 5th April 2014 and 18th June 2015, were screened for GATA4 mutations using direct sequencing of GATA4 coding exons. Statistical assessment of different risk factors, which is a retrospective study, was carried out using Chi-square and Fisher's exact tests. RESULTS: We identified seven exonic variants in nine patients (two missense and five synonymous variants); in addition of eight intronic variants. Assessment of environmental risk factors shows significant association of maternal passive smoking with TOF in the Moroccan population. CONCLUSION: The present study allowed, for the first time, the molecular and environmental characterisation of Moroccan TOF population. Our findings emphasise particularly the strong association of passive smoking with the emergence of tetralogy of Fallot.

[Fanconi anemia at the University Hospital (CHU) Hassan II of Fez: about 6 cases]. / Anémie de fanconi au CHU Hassan II Fès: à propos de 6 observations.

Fanconi anemia is a recessive disorder associated with chromosomal instability. It is marked by phenotypical heterogeneity which includes medullary deficiency, a variable malformation syndrome, a predisposition to develop acute leukaemias myéloïdes (ALM) and a cellular over-sensitiveness with the agents bridging the ADN. The diagnosis is based on the abnormal increase in the rate of spontaneous breaks chromosomal but especially and in a specific way, on a clear increase in these chromosomal breaks in the presence of bifunctional alkylating agents, which is the case in our six patients. Genetic counseling is that available for autosomal recessive diseases. We report our initial observations conducted at the University Hospital (CHU) Hassan II of Fez confirmed by the detection of a large chromosomal instability after culture with Mitomycin C compared to a normal control group. The purpose of this study was to update our knowledge of Fanconi anemia genes and to highlight the role of cytogenetics in its diagnosis and the genetic counseling for better management of affected children and their families.

NKX2-5 molecular screening and assessment of variant rate and risk factors of secundum atrial septal defect in a Moroccan population.

OBJECTIVE: Secundum atrial septal defect (ASDII) has multifactorial etiology that is combination of environmental (e.g., mother's exposure to toxicity, ethnicity) and genetic causes. Aim of the present study was to screen a Moroccan population with ASDII for NKX2-5 variants and to assess risk factors that may contribute to emergence of the disorder. METHODS: Thirty-two non-syndromic ASDII patients were screened for NKX2-5 variants using direct sequencing of polymerase chain reactionamplified coding regions. Risk factor rates were compared to general population and assessed using Fisher's exact and chi-square tests. In this retrospective study, criteria of exclusion were suggestive or confirmed syndrome association. RESULTS: Three heterozygous variants were detected in 4 patients. NKX2-5 variant rate in present cohort is estimated to be about 9.4%. Two prominent risk factors in the Moroccan population were highlighted: consanguinity, rate of which was significantly high at 30.8%, and previous maternal miscarriage or sibling sudden death, observed in 34.6% of cohort. CONCLUSION: Impact of identified variants was discussed and possible disease-predisposing effect is suggested. Findings indicate that ASD may be favored by consanguineous marriage and that NKX2-5 variant rate in ASD patients may be affected by ethnicity. High level of maternal miscarriage and sibling sudden death suggests potential non-sporadic nature as result of putative genetic defect.

[Lynch syndrome: case report and review of the literature]. / Syndrome de Lynch: à propos d'un cas et revue de la litterature.

Lynch syndrome or hereditary nonpolyposis colorectal cancer (HNPCC) is the most common form of hereditary colorectal cancers. It increases cancer susceptibility, the risk of colorectal cancer in first-degree, endometrial cancer in women, and to a lesser extent, other cancers (ovarian, small bowel, stomach, urinary tract and hepatobiliary). Thus, the cumulative risk of developing colorectal cancer or endometrial cancer at the age of 80 years rises to 20 and 40% respectively. These cancers are characterized by a positive family history, their occurrence at an early age, and by the development of metachronous cancers in the same individual. This syndrome is transmitted in an autosomal dominant manner. The genes whose alteration is associated with the presence of an HNPCC belong to the family of DNA mismatch repair genes (DNA mismatch repair or MMR): MSH2, MLH1, and MSH6 are involved, in decreasing order of frequency, in 35%, 25% and 2% of cases respectively. Colonoscopic and gynecological monitoring is recommended for patients with a constitutional mutation in MSH2, MLH1 or Msh6 genes. We report one of the first moroccan case with Lynch syndrome whose constitutional mutation in the MLH1 gene was identified in a family member with colon cancer. In reply to the inquiry ofother healthy family members, a presymptomatic diagnosis was made allowing to formulate an appropriate monitoring strategy. Our study aims to highlight the role of oncogenetics in the management of patients with cancer and their families.

Noonan syndrome-causing genes: Molecular update and an assessment of the mutation rate.

Noonan syndrome is a common autosomal dominant disorder characterized by short stature, congenital heart disease and facial dysmorphia with an incidence of 1/1000 to 2500 live births. Up to now, several genes have been proven to be involved in the disturbance of the transduction signal through the RAS-MAP Kinase pathway and the manifestation of Noonan syndrome. The first gene described was PTPN11, followed by SOS1, RAF1, KRAS, BRAF, NRAS, MAP2K1, and RIT1, and recently SOS2, LZTR1, and A2ML1, among others. Progressively, the physiopathology and molecular etiology of most signs of Noonan syndrome have been demonstrated, and inheritance patterns as well as genetic counseling have been established. In this review, we summarize the data concerning clinical features frequently observed in Noonan syndrome, and then, we describe the molecular etiology as well as the physiopathology of most Noonan syndrome-causing genes. In the second part of this review, we assess the mutational rate of Noonan syndrome-causing genes reported up to now in most screening studies. This review should give clinicians as well as geneticists a full view of the molecular aspects of Noonan syndrome and the authentic prevalence of the mutational events of its causing-genes. It will also facilitate laying the groundwork for future molecular diagnosis research, and the development of novel treatment strategies.

The first PTPN1 1 mutations in hotspot exons reported in Moroccan children with Noonan syndrome and comparison of mutation rate to previous studies.

BACKGROUND/AIM: Noonan syndrome is an autosomal dominant disorder with an incidence of 1/1000-2500. It results from protein-tyrosine phosphatase, nonreceptor type 11 (PTPN11) mutations in roughly 50% of cases. Mutational screening of PTPN11 has been carried out in different populations. Thus, the aim of this study was to screen, for the first time, PTPN11 mutations in a series of Moroccan Noonan syndrome patients. MATERIALS AND METHODS: We used bidirectional sequencing of exons 3 and 8, considered as PTPN11 mutation hot spots, and then compared the rate of mutational events of these exons between different populations using chi-square and Fisher's exact tests. RESULTS: We detected 3 heterozygous mutations (Asp6lGly, Tyr63Cys, and Asn308Ser) in 4 individuals of 16 sporadic patients (25%). The rate of mutation in our cohort did not differ from that of other populations. However, we found significant differences in the mutation rate of exon 8 between one Japanese cohort and some populations, which requires more investigations to be explained. CONCLUSION: The present study allowed identification of mutations clustered in exons 3 and 8 of the PTPN11 gene in a Moroccan Noonan syndrome cohort and enabled us to give appropriate genetic counseling to the mutation-positive patients.