Publications by authors named "Yosra Halleb"

3 Publications

  • Page 1 of 1

Expanding the clinical spectrum of STIP1 homology and U-box containing protein 1-associated ataxia.

J Neurol 2021 Jan 8. Epub 2021 Jan 8.

Service de Génétique Médicale, Hôpitaux de Brabois, CHRU de Nancy, Rue du Morvan, 54500, Vandoeuvre-lès-Nancy, France.

Background: STUB1 has been first associated with autosomal recessive (SCAR16, MIM# 615768) and later with dominant forms of ataxia (SCA48, MIM# 618093). Pathogenic variations in STUB1 are now considered a frequent cause of cerebellar ataxia.

Objective: We aimed to improve the clinical, radiological, and molecular delineation of SCAR16 and SCA48.

Methods: Retrospective collection of patients with SCAR16 or SCA48 diagnosed in three French genetic centers (Montpellier, Strasbourg and Nancy).

Results: Here, we report four SCAR16 and nine SCA48 patients from two SCAR16 and five SCA48 unrelated French families. All presented with slowly progressive cerebellar ataxia. Additional findings included cognitive decline, dystonia, parkinsonism and swallowing difficulties. The age at onset was highly variable, ranging from 14 to 76 years. Brain MRI showed marked cerebellar atrophy in all patients. Phenotypic findings associated with STUB1 pathogenic variations cover a broad spectrum, ranging from isolated slowly progressive ataxia to severe encephalopathy, and include extrapyramidal features. We described five new pathogenic variations, two previously reported pathogenic variations, and two rare variants of unknown significance in association with STUB1-related disorders. We also report the first pathogenic variation associated with both dominant and recessive forms of inheritance (SCAR16 and SCA48).

Conclusion: Even though differences are observed between the recessive and dominant forms, it appears that a continuum exists between these two entities. While adding new symptoms associated with STUB1 pathogenic variations, we insist on the difficulty of genetic counselling in STUB1-related pathologies. Finally, we underscore the usefulness of DAT-scan as an additional clue for diagnosis.
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January 2021

c.1227_1228dupGG (p.Glu410Glyfs), a frequent variant in Tunisian patients with MUTYH associated polyposis.

Cancer Genet 2020 01 4;240:45-53. Epub 2019 Nov 4.

Cytogenetic, Molecular Genetics and Human Reproduction Biology - FARHAT HACHED University Hospital, Sousse, Tunisia.

Introduction: Familial adenomatous polyposis (FAP) is an autosomal dominant-inherited disease caused by germline variants in the APC gene. It is characterized by the development of hundreds to thousands of adenomatous polyps in colon and rectum. Recently, biallelic germline variants in the base excision repair (BER) gene: MUTYH have been identified in patients with attenuated FAP and/or negative APC result. It can be responsible for an autosomal recessive inherited colorectal cancer syndrome (MAP syndrome: MUTYH-associated polyposis).

Objective: The aim of this study was to evaluate germline variants of MUTYH gene in Tunisian patients with attenuated FAP.

Methods: thirteen unrelated patients from Tunisia with attenuated FAP were screened for MUTYH germline variants. Direct sequencing was performed to identify point variants in this gene.

Results: A Biallelic MUTYH germline variant were found in all patients and showed an attenuated polyposis phenotype almost of them without extra-colic manifestations: The known pathogenic frameshift variant c.1227_1228dupGG (p. Glu410Glyfs) was found, in homozygous state, in 13 index patients.

Conclusion: Patients with attenuated familial adenomatous polyposis (<=100) and no obvious vertical transmission of the disease should be considered for MUTYH gene testing.
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January 2020

Transient neonatal diabetes mellitus and hypomethylation at additional imprinted loci: novel ZFP57 mutation and review on the literature.

Acta Diabetol 2019 Mar 13;56(3):301-307. Epub 2018 Oct 13.

Department of Human Cytogenetics, Molecular Genetics and Reproductive Biology, Farhat HACHED University Hospital, 4000, Sousse, Tunisia.

Aim: 6q24-related transient neonatal diabetes mellitus (6q24-TNDM) is a rare imprinting disorder characterized by uncontrolled hyperglycemia during the first 6 months of life. The molecular etiology of 6q24-TNDM is attributable to overexpression of the paternally inherited PLAGL1 and HYMAI genes located on the 6q24 locus. One of these major defects is maternal loss of methylation (LOM) at 6q24. In addition, approximately 50% of TNDM patients that present LOM at 6q24 can also display hypomethylation at additional imprinted loci (multilocus imprinting disturbances, MLID). Interestingly, the majority of these patients carry mutations in the ZFP57 gene, a transcription factor required for the adequate maintenance of methylation during early embryonic development.

Methods: Methylation analysis of 6q24 and additional imprinted loci was carried out by MS-MLPA in a Tunisian male patient with clinical diagnosis of TNMD. For the same patient, mutation analysis of the ZFP57 gene was conducted by direct Sanger sequencing.

Results: We report a novel nonsense mutation (c.373C > T; p.R125*; ENST00000376883.1) at the ZFP57 gene causing TNDM-MLID and describe detailed phenotype/epigenotype analysis of TNMD patients carrying ZFP57 mutations.

Conclusion: We provide additional support to the role of ZFP57 as a genetic determinant cause of MLID in patients with TNMD.
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March 2019