International Journal of Pediatric Otorhinolaryngology xxx (xxxx) xxx Please cite this article as: Ghita Amalou, International Journal of Pediatric Otorhinolaryngology, https://doi.org/10.1016/j.ijporl.2020.110481 Available online 2 November 2020 0165-5876/© 2020 Elsevier B.V. All rights reserved. Case Report A homozygous MPZL2 deletion is associated with non syndromic hearing loss in a moroccan family Ghita Amalou a, c, d , Crystel Bonnet b , Zied Riahi e , Aymane Bouzidi a, c, d , Soukaina Elrharchi a , Amale Bousfha a, h , Majida Charif c, i , Mostafa Kandil d , Guy Lenaers c , Christine Petit b, f, g , Abdelhamid Barakat a, * a Human Molecular Genetics Laboratory, Institut Pasteur du Maroc, Casablanca, Morocco b Genetics and Physiology of Hearing Laboratory, Institut Pasteur, 75015, Paris, France c MitoLab Team, Institut MitoVasc, UMR CNRS 6015, INSERM U1083, Universit´ e d’Angers, Angers, France d Team of Anthropogenetics and Biotechnologies, Faculty of Sciences, Chouaib Doukkali University, Eljadida, Morocco e Complexit´ e Du Vivant, Sorbonne Universit´ es, 75005, Paris, France f Institut de L’Audition, 75012, Paris, France g Coll` ege de France, 75005, Paris, France h Laboratoire de Physiopathologie et G´ en´ etique Mol´ eculaire, Facult´ e des Sciences Ben M’sik, Universit´ e Hassan II, Casablanca, Morocco i Genetics, and Immuno-cell Therapy Team, Mohammed First University, Oujda, Morocco A R T I C L E INFO Keywords: MPZL2 Non syndromic hearing loss Morocco ABSTRACT Adhesion glycoproteins are implicated in the pathophysiology of hearing loss, the most frequent inherited sensory disorder, affecting 1 in 1000 new-borns. Exome sequencing of a consanguineous Moroccan patient with mild hearing loss identifed for the frst time in a North African family a single homozygous mutation c.72delA in MPZL2 gene, encoding the Myelin Protein Zero-Like 2, reported as causing deafness in two other populations. Variable tandem repeat genotyping of this family revealed that the c.72delA MPZL2 allele shared a common haplotype with Turkish and Dutch families. These results confrm the pathogenicity of this MPZL2 mutation in recessive mild to moderate non-syndromic deafness. 1. Introduction Hearing loss (HL) is the most frequent sensory disorder affecting 1 in 1000 new-borns in the world population. HL is categorized in several ways: conductive HL typically implies a defect of the outer or middle ear while sensorineural HL refers to a defect of the inner ear [1]. In 70% of neonates who fail newborn hearing screens (NBHS) and are presumed to have inherited HL, there are no other distinguishing physical fndings and the HL is classifed as nonsyndromic [2]. In most cases, a genetic origin related to one of the 121 genes associated to non-syndromic HL (NSHL) is responsible for the symptom. Today, more than 70 genes and 85 locus have been identifed for the recessive NSHL (https://heredit aryhearingloss.org/accessed on December 29, 2019) 1 . In Morocco, GJB2 gene is the primary cause of hearing impairment, with mutations identifed in 43% of the studied NSHL cases [3]. In two recent studies, mutations in MPZL2 (OMIM: 604873) 2 were newly found as the cause of autosomal recessive deafness-111 (DFNB111) [4,5]. MPZL2 encodes the Myelin Protein Zero-Like 2, a transmembrane glycoprotein member of the immunoglobulin super-family, implicated in homophilic and heterophilic cell-cell adhe- sion mediation [5]. A single homozygous deletion c.72delA (p.Ile24- Metfs*22) was found in 12 patients with a non-syndromic symmetrical mild to moderate hearing impairment, from fve consanguineous fam- ilies: Dutch [5], Turkmen ethnicity from north-eastern Iran [4] and Turkish [4,5] origins. We present in this study the result of a whole exome sequencing of a patient from a consanguineous Moroccan family affected with NSHL associated to a MPZL2 deletion for the frst time in North Africa; and the * Corresponding author. Laboratoire de G´ enomique et G´ en´ etique Humaine, D´ epartement de Recherche Scientifque, Institut Pasteur du Maroc, 1 Place Louis Pasteur, 20360, Casablanca, Morocco. E-mail address: hamid.barakat@pasteur.ma (A. Barakat). 1 HHL, https://hereditaryhearingloss.org 2 OMIM, http://www.omim.org Contents lists available at ScienceDirect International Journal of Pediatric Otorhinolaryngology journal homepage: www.elsevier.com/locate/ijporl https://doi.org/10.1016/j.ijporl.2020.110481 Received 20 June 2020; Received in revised form 29 October 2020; Accepted 29 October 2020