[Williams-Beuren syndrome: a retrospective study of a series of 11 cases at the Mohammed VI University Hospital in Marrakech]

Williams-Beuren syndrome is a rare genetic disease (1/20 000) characterized by a microdeletion at 7q11.23 encompassing about 28 genes, including the elastin gene, ELN. It is a sporadic disease in the majority of cases. Easily identifiable in childhood, this developmental disorder associates suggestive face dysmorphism, cardiac defect, psychomotor retardation and specific behavioural and cognitive profile. We conducted a retrospective study of 11 patients with Williams-Beuren syndrome whose data were collected in the Genetics Department of the Mohammed VI University Hospital of Marrakech. The average age of patients was 6.05 years (SD=6.56; interquartile range=5), with a female predominance (64%; 7/11 patients). Almost all patients were mentally retarded and the diagnosis was confirmed in 100% (11) of patients using fluorescence in situ hybridisation (FISH).

[Contribution of cytogenetic in the diagnosis of Edwards's syndrome: about 9 cases]

INTRODUCTION

Trisomy 18 is a constitutional chromosomal disorder defined by the presence of a supernumerary chromosome 18. The diagnosis is suspected clinically and confirmed by cytogenetic analysis. Genetic counseling for patients' families is important. The objective of this study is to report our experience in Medical Genetics Department at the Mohammed VI University Hospital of Oujda in the diagnosis and genetic counseling of trisomy 18 through dysmorphological expertise and cytogenetic analysis.

MATERIAL AND METHODS

We report a retrospective descriptive study over a period of four years (2018-2022) of nine patients with polymalformative syndrome suggestive of trisomy 18 who underwent cytogenetic analysis.

RESULTS

The median age of patients at diagnosis was 2 days with a male predominance. The mean maternal age at birth of the patients in our series was 40 years. Consanguinity was found in only one patient. All patients had a typical phenotype of trisomy 18. The postnatal constitutional karyotype showed a homogeneous trisomy 18 in all patients. In our series, only one patient is still alive at the age of 7 months, the other 8 patients died with a median postnatal survival of 5 days.

CONCLUSION

We underline through this study, the contribution of the medical geneticist in the clinic and cytogenetic diagnostic approach of rare chromosomal affections, in order to provide an adequate genetic counseling to the families.

Double Isochromosome X, a Rare Cytogenetic Variant of Turner Syndrome: A Case Report and a Review of the Literature

Turner Syndrome (TS) is a genetic disorder caused by total or partial loss of an X chromosome. The isochromosome X (i(X)) is a known variant of TS, however, double i(X) is a very rare variant, reported very few times in the literature. We report on a rare case of TS with double i(X). This is an 11-year-old female patient , addressed to the medical genetics consultation for short stature and facial features suggestive of TS. We performed a constitutional postnatal karyotype from a peripheral blood sample, with lymphocyte culture, and an R band analysis, performed on 70 metaphases. Metaphases analysis in our patient identified the presence of three cell populations: 45,X[22]/46,X,i(X)(q10)[30]/47,X,i(X)(q10),i(X)(q10) [18]. The first has total chromosome X monosomy, the second with a normal X chromosome and one isochromosome of the long arm of the other X chromosome and the third with a normal X chromosome and two isochromosomes of the long arm of the X chromosome. A control cell culture was performed from a second blood sample of the patient and confirmed the abnormality. This paper will discuss this case in comparison with other rare cases described, as well as the formation of the double isochromosome, based on the literature.

Clinical description and mutational profile of a Moroccan series of patients with Rubinstein Taybi syndrome

Background

Rubinstein-Taybi syndrome (RSTS; OMIM 180849) is a rare autosomal dominant developmental disorder with an estimated prevalence of one case per 125,000 live births. RSTS is characterized by typical face, broad thumbs and halluces, short stature, and intellectual disability. Facial dysmorphy is characteristic with microcephaly, low frontal hairline, arched eyebrows, long eyelashes, convex profile of nose, narrow palate, and micrognathia. RSTS is mainly due to mutations or microdeletions of the CREBBP gene (about 60%) and more rarely of the EP300 gene (8%).

Objective

Clinical description and identification of mutations of patients with Rubinstein Taybi syndrome

Methods

PCR and direct sequencing of CREBBP gene.

Results

We report here, the clinical and molecular data of a series of six Moroccan patients with a phenotype of RSTS. The molecular study of the major gene CREBBP (by Sanger Sequencing followed by CGH array, if sequence normal) revealed point mutations in five patients. For the sixth patient, CGH array revealed a microdeletion carrying the CREBBP gene. Through this work, we emphasize the importance of clinical expertise in the diagnosis, management and genetic counseling in Rubinstein Taybi syndrome.

Patients' Knowledge and Attitude Toward Biobanks in Eastern Morocco

Background: To integrate biobanks into the Moroccan health system and to promote biobanks-based research projects, it is necessary to explore the knowledge of patients, their attitudes toward biobanks, and the reasons that motivate them to participate in biobanks. Methods: Face-to-face interviews were conducted with patients, and data were analyzed using SPSS. Results: One thousand one hundred thirty-three questionnaires were completed. The mean age of patients was 47.74 years (SD 15.26 years). More women (69%) were involved in this survey. Of the respondents, 97% had never heard of the term "biobanks." Knowledge of biobanks varied significantly with respondents' education level. Overall, 80.7% of the participants (n = 914) expressed their willingness to participate in biobanking through donation of biospecimens associated with personnel and health data. Willingness to participate in biobanks was significantly associated with gender and age. We found that the main barriers to participation in biobanks were the lack of trust in biomedical research and concerns about privacy. When asked about the preferred type of consent, the majority of patients (75%) opted for a one-time consent. Conclusion: Despite the lack of knowledge of biobanks among patients in Eastern Morocco, the majority of them expressed willingness to participate in biobanking through donation of biospecimens. However, active participation depended upon a number of factors, notably, the trust in biomedical research and privacy. Therefore, more efforts are needed to increase awareness and promote wider participation in biobanking.

[Lung cancer in Eastern Morocco: where do we stand?]

Introduction

Lung cancer is the most common cancer in men living Eastern Morocco. We here present the first report on the clinical, pathological and therapeutic features of lung cancer in Eastern Morocco.

Methods

We conducted a retrospective study of 738 patients diagnosed with lung cancer at the Hassan II, Oncology Center between October 2005 and December 2014.

Results

Among the cases studied, 671 patients were men and 67 women; 95.01% of men and 1.54% of women were smokers. The average age of patients was 59.1 ± 11.9 years. Most patients (97%) were diagnosed at advanced stage disease. Only 4 out of 227 patients with advanced adenocarcinoma underwent molecular test. In addition, no patient in our series received targeted therapy. In this series, 20.46% of patients had less than 50 years. Compared to patients aged 50 years and older, cannabis consumption was higher (p<0.001) in patients less than 50 years and as well as a higher rate of adenocarcinoma (p<0.01). By contrast, in these patients, tobacco consumption was lower (p<0.001) as well as the rate of squamous cell carcinoma (p<0.01) and small cell cancer (p<0.05).

Conclusion

Unlike Western countries, in Eastern Morocco lung cancer is diagnosed late, affects younger people and access to molecular tests is still very limited. These results justify the need to implement effective programs against lung cancer as well as to facilitate access to molecular tests and new therapeutic tools in Eastern Morocco.

Ellis-Van Creveld Syndrome and Dandy-Walker Malformation: An Uncommon Association

Ellis-Van Creveld (EvC) syndrome is a rare autosomal recessive chondroectodermal dysplasia including chondrodysplasia, postaxial polydactyly, ectodermal dysplasia, and congenital heart disease in 60% of patients. Additional findings may be observed affecting the pulmonary, renal, gastrointestinal, hematologic, and central nervous systems. We report a case of an 11-year-old Moroccan boy with EVC syndrome and Dandy-Walker malformation. To our knowledge, this association has been previously reported in 3 patients in the literature.

Acromelic frontonasal dysostosis and ZSWIM6 mutation: phenotypic spectrum and mosaicism

Acromelic frontonasal dysostosis (AFND) is a distinctive and rare frontonasal malformation that presents in combination with brain and limb abnormalities. A single recurrent heterozygous missense substitution in ZSWIM6, encoding a protein of unknown function, was previously shown to underlie this disorder in four unrelated cases. Here we describe four additional individuals from three families, comprising two sporadic subjects (one of whom had no limb malformation) and a mildly affected female with a severely affected son. In the latter family we demonstrate parental mosaicism through deep sequencing of DNA isolated from a variety of tissues, which each contain different levels of mutation. This has important implications for genetic counselling.

AGXT Gene Mutations and Prevalence of Primary Hyperoxaluria Type 1 in Moroccan Population

INTRODUCTION

Primary hyperoxaluria type 1 (PH1) is an autosomal recessive disorder caused by deficiency of alanine glyoxylate aminotransferase, due to a defect in the AGXT gene. Several mutations in this gene have been reported and some of them have been observed in multiple populations. The aim of our study was to analyze the mutations causing PH1 in the Moroccan population and to estimate its prevalence in Morocco.

METHODS

Molecular studies of 29 unrelated Moroccan patients with PH were performed by direct sequencing of all exons of the AGXT gene. In addition, to estimate the prevalence of PH1, we screened for the recurrent p.Ile244Thr mutation in 250 unrelated Moroccan newborns using real-time polymerase chain reaction.

RESULTS

Four pathogenic mutations were detected in 25 unrelated patients. The c.731T>C (p.Ile244Thr) was the most frequent mutation with a frequency of 84%. The other three mutations were c.33delC, c.976delG, and c.331C>T. The prevalence of the PH1 mutation among Moroccans was then estimated to range from 1/7267 to 1/6264.

CONCLUSION

PH1 is one of the most prevalent genetic diseases in the Moroccan population and is probably underdiagnosed. Front line genetic testing for PH1 in Morocco should be initiated using an assay for the recurrent p.Ile244Thr mutation. This strategy would provide a useful tool for precocious diagnosis of presymptomatic individuals and to prevent their rapid progression to renal failure.

Search for ReCQL4 mutations in 39 patients genotyped for suspected Rothmund-Thomson/Baller-Gerold syndromes

Three overlapping conditions, namely Rothmund-Thomson (RTS), Baller-Gerold (BGS) and RAPADILINO syndromes, have been attributed to RECQL4 mutations. Differential diagnoses depend on the clinical presentation, but the numbers of known genes remain low, leading to the widespread prescription of RECQL4 sequencing. The aim of our study was therefore to determine the best clinical indicators for the presence of RECQL4 mutations in a series of 39 patients referred for RECQL4 molecular analysis and belonging to the RTS (27 cases) and BGS (12 cases) spectrum. One or two deleterious RECQL4 mutations were found in 10/27 patients referred for RTS diagnosis. Clinical and molecular reevaluation led to a different diagnosis in 7/17 negative cases, including Clericuzio-type poikiloderma with neutropenia, hereditary sclerosing poikiloderma, and craniosynostosis/anal anomalies/porokeratosis. No RECQL4 mutations were found in the BGS group without poikiloderma, confirming that RECQL4 sequencing was not indicated in this phenotype. One chromosomal abnormality and one TWIST mutation was found in this cohort. This study highlights the search for differential diagnoses before the prescription of RECQL4 sequencing in this clinically heterogeneous group. The combination of clinically defined subgroups and next-generation sequencing will hopefully bring to light new molecular bases of syndromes with poikiloderma, as well as BGS without poikiloderma.

Germline mosaicism in Rubinstein-Taybi syndrome

Rubinstein-Taybi syndrome is an autosomal dominant disorder with multiple congenital anomalies and genetic heterogeneity. Clinical manifestations include mental retardation, postnatal growth deficiency, microcephaly, broad thumbs and halluces, and characteristic facial features. Mutations in the gene encoding the transcriptional coactivator CREB-binding protein (CREBBP; OMIM 600140) on chromosome 16p13, account for about 50% to 70% of patients. Most of CREBBP mutations are de novo and the rate of recurrence in a family is low. Families with several affected children are extremely rare. We report here a Moroccan family with two children with RSTS and apparently unaffected parents. The molecular studies showed a heterozygous mutation c.4361T>A (p.Leu1454His) in exon 26 of the CREBBP gene in the two affected siblings. Neither the parents, nor the healthy brother, carry this mutation in hematologic cells. The mutation was also absent in buccal epithelial cells of both parents. We discuss the hypothesis of germinal mosaicism. This concept is very important because it complicates genetic counseling of this family who has a risk of recurrence of the mutation in subsequent pregnancies.

[Prenatal diagnosis of trisomy 21 by fluorescence in situ hybridization (FISH): about the first tests in Morocco]

Introduction

Méthodes

Résultats

Conclusion

An inherited LMNA gene mutation in atypical Progeria syndrome

Hutchinson-Gilford Progeria syndrome (HGPS) is a rare genetic disorder, characterized by several clinical features that begin in early childhood, recalling an accelerated aging process. The diagnosis of HGPS is based on the recognition of common clinical features and detection of the recurrent heterozygous c.1824C>T (p.Gly608Gly) mutation within exon 11 in the Lamin A/C encoding gene (LMNA). Besides "typical HGPS," several "atypical progeria" syndromes (APS) have been described, in a clinical spectrum ranging from mandibuloacral dysplasia to atypical Werner syndrome. These patients's clinical features include progeroid manifestations, such as short stature, prominent nose, premature graying of hair, partial alopecia, skin atrophy, lipodystrophy, skeletal anomalies, such as mandibular hypoplasia and acroosteolyses, and in some cases severe atherosclerosis with metabolic complications. APS are due in several cases to de novo heterozygous LMNA mutations other than the p.Gly608Gly, or due to homozygous BAFN1 mutations in Nestor-Guillermo Progeria syndrome (NGPS). We report here and discuss the observation of a non-consanguineous Moroccan patient presenting with atypical progeria. The molecular studies showed the heterozygous mutation c.412G>A (p.Glu138Lys) of the LMNA gene. This mutation, previously reported as a de novo mutation, was inherited from the apparently healthy father who showed a somatic cell mosaicism.

Frequency of IL28B rs12979860 single-nucleotide polymorphism alleles in newborn infants and in patients with chronic hepatitis C in Morocco

BACKGROUND

Epidemiological and experimental evidence support the role of host genetics in treatment response and viral clearance in chronic hepatitis C (CHC). Recently, the CC genotype of IL28B single-nucleotide polymorphism (SNP) rs12979860 has been associated with spontaneous viral clearance and a better treatment response. The distribution of this polymorphism varies according to populations. Frequency of rs12979860 SNP alleles in the Moroccan population is unknown. The aim of our study was to estimate the frequency of the C allele of this SNP in the Moroccan population and, in parallel, in a cohort of Moroccan patients with CHC treated with pegylated interferon-alpha and ribavirin.

METHODS

We used real-time polymerase chain reaction assay based on TaqMan technology to determine the allele frequency of the rs12979860 SNP in 100 Moroccan newborn infants. We also compared the frequency of the CC genotype between two groups of patients with genotype 1-CHC treated by combination therapy: group1, n=30 patients, responders who achieved sustained viral response (SVR) and group2, n=30 patients, nonresponders.

RESULTS

The rs12979860 C allele frequency was estimated to be 73% in the Moroccan population. The frequency of this allele in the group of patients with CHC was only 58.3%, and the CC genotype is more prevalent in group1 (62.5%) than in group 2.

CONCLUSIONS

This is the first report providing genetic data related to the frequency of genetic polymorphisms of IL28B in Morocco. The C-allele frequency of the IL28B gene SNP rs12979860 in Morocco is higher than in the African populations. Distribution of this SNP distinguishes in a population of CHC between SVR and nonresponders. This result merits consideration and should be studied by analyzing a larger sample size of patients.

[Costello syndrome: report of a case]

Le syndrome de Costello appelé également syndrome Facio-cutanéo-squelettique est une anomalie rare du développement d'origine génétique de transmission autosomique dominante. Sa prévalence est inconnue mais environ 250 cas ont été rapportés dans la littérature. La majorité des cas sont sporadiques. Les principaux signes sont une dysmorphie faciale caractéristique, un retard mental, un retard de croissance, un cutis laxa, une malformation cardiaque et des papillomes péri-orificiels. Sur le plan génétique, ce syndrome est dû à des mutations au niveau du gène HRAS qui est un oncogène de la famille Ras. Ceci est à l'origine de la prédisposition de ces patients au développement de tumeurs malignes. Le pronostic dépend de la sévérité de la cardiopathie et de la survenue de tumeurs malignes. Les principaux diagnostics différentiels incluent le syndrome de Noonan et le syndrome cardio-facio-cutané. Nous rapportons dans ce travail, une patiente âgée de 13 ans qui présente des signes cliniques du syndrome de Costello. L'analyse moléculaire du gène HRAS a mis en évidence la mutation c.34G>A; p.Gly12Ser de novo au niveau de l'exon 1 de ce gène. Nous montrons à travers cette observation l'intérêt de l’étude moléculaire pour confirmer le diagnostic du syndrome de Costello et pour le conseil génétique de la famille.