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Wonkam‐Tingang E, Nguefack S, Esterhuizen AI, Chelo D, Wonkam A. DMD-related muscular dystrophy in Cameroon: Clinical and genetic profiles. Mol Genet Genomic Med 2020; 8:e1362. [PMID: 32543101 PMCID: PMC7434738 DOI: 10.1002/mgg3.1362] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2020] [Revised: 05/20/2020] [Accepted: 05/26/2020] [Indexed: 12/20/2022] Open
Abstract
BACKGROUND Most of the previous studies on Duchenne Muscular Dystrophy (DMD) were conducted in Caucasian, Asian, and Arab populations. Therefore, little is known about the features of this disease in Africans. In this study, we aimed to determine the clinical characteristics of DMD, and the common mutations associated with this condition in a group of Cameroonian patients. METHODS We recruited DMD patients and performed a general physical examination on each of them. Multiplex ligand-dependant probe amplification was carried out to investigate exon deletions and duplications in the DMD gene (OMIM: 300377) of patients and their mothers. RESULTS A total of 17 male patients from 14 families were recruited, aged 14 ± 5.1 (8-23) years. The mean age at onset of symptoms was 4.6 ± 1.5 years, and the mean age at diagnosis was 12.1 ± 5.2 years. Proximal muscle weakness was noted in all patients and calf hypertrophy in the large majority of them (88.2%; 15/17). Flexion contractures were particularly frequent on the ankle (85.7%; 12/14). Wasting of shoulder girdle and thigh muscles was present in 50% (6/12) and 46.2% (6/13) of patients, respectively. No patient presented with hearing impairment. Deletions in DMD gene (OMIM: 300377) occurred in 45.5% of patients (5/11), while duplications were observed in 27.3% (3/11). Both mutation types were clustered between exons 45 and 50, and the proportion of de novo mutation was estimated at 18.2% (2/11). CONCLUSION Despite the first symptoms of DMD occurring in infancy, the diagnosis is frequently made later in adolescence, indicating an underestimation of the number of cases of DMD in Cameroon. Future screening of deletions and duplications in patients from Cameroon should focus on the distal part of the gene.
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Affiliation(s)
- Edmond Wonkam‐Tingang
- Division of Human GeneticsDepartment of PathologyUniversity of Cape TownCape TownSouth Africa
| | - Séraphin Nguefack
- Department of PaediatricsFaculty of Medicine and Biomedical SciencesUniversity of Yaoundé IYaoundéCameroon
- Paediatrics UnitDivision of Paediatric NeurologyGynaeco‐Obstetric and Paediatric HospitalYaoundéCameroon
| | - Alina I. Esterhuizen
- Division of Human GeneticsDepartment of PathologyUniversity of Cape TownCape TownSouth Africa
- National Health Laboratory ServiceGroote Schuur HospitalCape TownSouth Africa
| | - David Chelo
- Department of PaediatricsFaculty of Medicine and Biomedical SciencesUniversity of Yaoundé IYaoundéCameroon
- Division of Paediatric Cardiology, Mother and Child HospitalYaoundéCameroon
| | - Ambroise Wonkam
- Division of Human GeneticsDepartment of PathologyUniversity of Cape TownCape TownSouth Africa
- Department of MedicineUniversity of Cape TownCape TownSouth Africa
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Evaluation of the behavioral characteristics of the mdx mouse model of duchenne muscular dystrophy through operant conditioning procedures. Behav Processes 2017; 142:8-20. [PMID: 28532665 DOI: 10.1016/j.beproc.2017.05.012] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2016] [Revised: 05/15/2017] [Accepted: 05/16/2017] [Indexed: 11/20/2022]
Abstract
The mdx mouse is an important nonhuman model for Duchenne muscular dystrophy (DMD) research. Characterizing the behavioral traits of the strain relative to congenic wild-type (WT) mice may enhance our understanding of the cognitive deficits observed in some humans with DMD and contribute to treatment development and evaluation. In this paper we report the results of a number of experiments comparing the behavior of mdx to WT mice in operant conditioning procedures designed to assess learning and memory. We found that mdx outperformed WT in all learning and memory tasks involving food reinforcement, and this appeared to be related to the differential effects of the food deprivation motivating operation on mdx mice. Conversely, WT outperformed mdx in an escape/avoidance learning task. These results suggest motivational differences between the strains and demonstrate the potential utility of operant conditioning procedures in the assessment of the behavioral characteristics of the mdx mouse.
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Chaussenot R, Edeline JM, Le Bec B, El Massioui N, Laroche S, Vaillend C. Cognitive dysfunction in the dystrophin-deficient mouse model of Duchenne muscular dystrophy: A reappraisal from sensory to executive processes. Neurobiol Learn Mem 2015; 124:111-22. [PMID: 26190833 DOI: 10.1016/j.nlm.2015.07.006] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2015] [Revised: 07/09/2015] [Accepted: 07/10/2015] [Indexed: 01/08/2023]
Abstract
Duchenne muscular dystrophy (DMD) is associated with language disabilities and deficits in learning and memory, leading to intellectual disability in a patient subpopulation. Recent studies suggest the presence of broader deficits affecting information processing, short-term memory and executive functions. While the absence of the full-length dystrophin (Dp427) is a common feature in all patients, variable mutation profiles may additionally alter distinct dystrophin-gene products encoded by separate promoters. However, the nature of the cognitive dysfunctions specifically associated with the loss of distinct brain dystrophins is unclear. Here we show that the loss of the full-length brain dystrophin in mdx mice does not modify the perception and sensorimotor gating of auditory inputs, as assessed using auditory brainstem recordings and prepulse inhibition of startle reflex. In contrast, both acquisition and long-term retention of cued and trace fear memories were impaired in mdx mice, suggesting alteration in a functional circuit including the amygdala. Spatial learning in the water maze revealed reduced path efficiency, suggesting qualitative alteration in mdx mice learning strategy. However, spatial working memory performance and cognitive flexibility challenged in various behavioral paradigms in water and radial-arm mazes were unimpaired. The full-length brain dystrophin therefore appears to play a role during acquisition of associative learning as well as in general processes involved in memory consolidation, but no overt involvement in working memory and/or executive functions could be demonstrated in spatial learning tasks.
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Affiliation(s)
- Rémi Chaussenot
- Paris-Saclay Neuroscience Institute, UMR 9197, CNRS, F-91405 Orsay, France; Univ. Paris-Sud, UMR 9197, F-91405 Orsay, France; Université Paris-Saclay, France
| | - Jean-Marc Edeline
- Paris-Saclay Neuroscience Institute, UMR 9197, CNRS, F-91405 Orsay, France; Univ. Paris-Sud, UMR 9197, F-91405 Orsay, France; Université Paris-Saclay, France
| | - Benoit Le Bec
- Paris-Saclay Neuroscience Institute, UMR 9197, CNRS, F-91405 Orsay, France; Univ. Paris-Sud, UMR 9197, F-91405 Orsay, France; Université Paris-Saclay, France
| | - Nicole El Massioui
- Paris-Saclay Neuroscience Institute, UMR 9197, CNRS, F-91405 Orsay, France; Univ. Paris-Sud, UMR 9197, F-91405 Orsay, France; Université Paris-Saclay, France
| | - Serge Laroche
- Paris-Saclay Neuroscience Institute, UMR 9197, CNRS, F-91405 Orsay, France; Univ. Paris-Sud, UMR 9197, F-91405 Orsay, France; Université Paris-Saclay, France
| | - Cyrille Vaillend
- Paris-Saclay Neuroscience Institute, UMR 9197, CNRS, F-91405 Orsay, France; Univ. Paris-Sud, UMR 9197, F-91405 Orsay, France; Université Paris-Saclay, France.
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Abstract
Many human syndromes associated with hearing loss are caused by disease genes located on the X chromosome, but few X-linked loci for non-syndromic hearing loss have been reported. Surprisingly, a Y-linked locus has been identified, representing one of the only disease loci on the Y chromosome. This study reviews the different sex-linked genes and loci on the X- and Y chromosome leading to syndromic and especially non-syndromic hearing loss.
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Affiliation(s)
- M B Petersen
- Department of Genetics, Institute of Child Health, Athens, Greece
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Pillers DAM, Kempton JB, Duncan NM, Pang J, Dwinnell SJ, Trune DR. Hearing loss in the laminin-deficient dy mouse model of congenital muscular dystrophy. Mol Genet Metab 2002; 76:217-24. [PMID: 12126936 DOI: 10.1016/s1096-7192(02)00039-2] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Sensorineural hearing loss is found in many inherited forms of muscular dystrophy. We investigated the dy mouse model, which has congenital muscular dystrophy due to a defect in laminin alpha 2, for evidence of cochlear dysfunction. Auditory brainstem response (ABR) audiometry to pure tones was used to evaluate 3-month-old homozygous dy/dy and age-matched C57 control mice. The average ABR thresholds to tone-burst stimuli for four frequencies (4, 8, 16, and 32 kHz) were determined and statistically compared by ANOVA. The dy/dy mice demonstrated elevated auditory thresholds ranging from 25 to 27 dB at each frequency tested (p<0.0001). Anatomic evaluations of the ears revealed pathology ranging from extensive connective tissue infiltration within the inner ear to possible minor defects in the cells of the organ of Corti. These anatomic and physiologic observations suggest that the extracellular matrix protein laminin plays a crucial role in normal cochlear function. Furthermore, the dy congenital muscular dystrophy mouse offers a novel model for evaluation of sensorineural hearing loss associated with muscular dystrophy.
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Affiliation(s)
- De-Ann M Pillers
- Department of Pediatrics, Oregon Retinal Degeneration Center, Oregon Child Health Research Center, Doernbecher Children's Hospital, Oregon Health Sciences University, 3181 S.W. Sam Jackson Park Road, Portland, OR 97201-3042, USA.
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Chen TJ, Chen SS, Wang DC, Hsieh YL. Increased vulnerability of auditory system to noise exposure in mdx mice. Laryngoscope 2002; 112:520-5. [PMID: 12148865 DOI: 10.1097/00005537-200203000-00021] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVES Dystrophin is a cytoskeletal protein mainly found just beneath the sarcolemma. Lack of dystrophin is known to be the cause of Duchenne muscular dystrophy (DMD). Other tissues, including the brain, retina, and cochlear hair cells, also express dystrophin. Recently, a gene (Xp21.2) associated with sensorineural hearing impairment has been mapped within the localization site for dystrophin in two families. Thus, it is reasonable to assume that dystrophin may play a role in auditory function. However, animal studies have produced conflicting results. STUDY DESIGN An attempt was made to clarify the differences between the auditory systems of dystrophin-deficient mdx mice and control B-10 mice by exposure to noise. METHODS In the present study, mdx mice and B-10 mice were used. Animals were exposed daily to noise for 1 month, and their auditory functions were evaluated by recording the brainstem auditory evoked potentials (BAEPs). RESULTS Before noise exposure, the mdx mouse demonstrated normal BAEP threshold when compared with the B-10 mouse. After 1 month of noise exposure, the B-10 mouse showed no apparent change in hearing threshold and BAEP latencies. In contrast, significantly increased hearing threshold and prolonged BAEP peak and interpeak latencies were observed in the mdx mouse after noise exposure. CONCLUSIONS These results indicate that the mdx mice are more vulnerable to noise damage. This involves not only the peripheral auditory system, but also the brainstem central auditory pathway. Therefore, a significant role for dystrophin in the auditory system, especially under noise stress, is suggested.
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Affiliation(s)
- Tsan-Ju Chen
- Department of Physiology, Graduate Institute of Medicine, Kaohsiung Medical University, Taiwan.
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Pillers DA, Duncan NM, Dwinnell SJ, Rash SM, Kempton JB, Trune DR. Normal cochlear function in mdx and mdx(Cv3) Duchenne muscular dystrophy mouse models. Laryngoscope 1999; 109:1310-2. [PMID: 10443839 DOI: 10.1097/00005537-199908000-00023] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVES/HYPOTHESIS Sensorineural hearing loss has been found in association with inherited muscular dystrophies in humans and in mouse models. An increased brainstem auditory evoked response threshold has been previously reported in the dystrophin-deficient mdx mouse model for Duchenne muscular dystrophy, suggesting that full-length dystrophin (Dp427) is involved in hearing. The objective of the present study was to confirm cochlear dysfunction with this gene defect and determine whether the shorter carboxyl terminus isoforms of dystrophin are also critical in maintaining normal hearing. STUDY DESIGN Case controlled. Animal model. METHODS Auditory brainstem response (ABR) audiometry to pure tones was used to evaluate cochlear function. Fourteen mdx, 4 mdx(Cv3), and 13 age-matched control (C57BL/6J and C57BL/10ScSn) male mice were tested at 5 weeks and 11 weeks of age. The ABR thresholds to tone-burst stimuli at 4, 8, 16, and 32 kHz were obtained for each ear and statistically compared (ANOVA) for potential group differences. RESULTS Both mdx and mdx(Cv3) mice demonstrated normal ABR thresholds when compared with controls. CONCLUSIONS Both mdx and mdx(Cv3) mouse models have normal hearing by ABR. The authors' data suggest that dystrophin and its carboxyl terminus isoforms do not play a critical role in hearing in the mouse. This was unexpected, as previous studies using the brainstem auditory evoked response method suggested that the mdx mouse has an increased threshold for hearing.
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Affiliation(s)
- D A Pillers
- Department of Pediatrics, Oregon Child Health Research Center, Doernbecher Children's Hospital, Oregon Health Sciences University, Portland 97201-3042, USA.
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Pfister MH, Apaydin F, Turan O, Bereketoglu M, Bilgen V, Braendle U, Kose S, Zenner HP, Lalwani AK. Clinical evidence for dystrophin dysfunction as a cause of hearing loss in locus DFN4. Laryngoscope 1999; 109:730-5. [PMID: 10334222 DOI: 10.1097/00005537-199905000-00010] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
OBJECTIVE Locus DFN4 is an X-linked nonsyndromic hearing loss locus originally mapped to Xp21.2. Recently, we have mapped deafness in a second family from Turkey to the same region, refining the location to within the Duchenne muscular dystrophy (DMD) locus. The objective of this study was to characterize the clinical phenotype of the Turkish family with comprehensive audiovestibular testing and high-resolution temporal bone computerized tomography. METHODS Fourteen members of a three-generation family were studied in detail including two deaf affected males. Members of the family underwent general physical and otologic examination, vestibular testing, pure-tone audiometry, otoacoustic emissions, and immitance testing. An affected male underwent high-resolution computerized tomography of the temporal bone, electroretinogram (ERG), electromyography, electroneurography, and determination of serum creatinine phosphokinase level. RESULTS Affected males were congenitally deaf with normal vestibular function. Carrier females showed a mild sensorineural hearing loss affecting all frequencies and absent otoacoustic emissions. Otoacoustic emissions in a younger, 3-year-old carrier girl were normal. In an affected male, ERG demonstrated subnormal scotopic b-wave typically seen in DMD. Computerized tomography of the temporal bone was normal. With the exception of the ERG finding, there was no clinical or laboratory evidence of DMD or Becker muscular dystrophy (BMD). CONCLUSION The abnormal ERG in the Turkish family in conjunction with mapping of the DFN4 locus to within DMD strongly suggests that a defect in dystrophin is responsible for the hearing loss in this family. Patients with DMD and BMD should be screened systematically for sensorineural hearing loss. This family provides additional evidence for the critical role of cytoskeletal proteins in normal hearing.
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Affiliation(s)
- M H Pfister
- Laboratory of Molecular Otology, Epstein Laboratories, University of California, San Francisco 94143-0526, USA
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Pfister MH, Apaydin F, Turan O, Bereketoglu M, Bylgen V, Braendle U, Zenner HP, Lalwani AK. A second family with nonsyndromic sensorineural hearing loss linked to Xp21.2: refinement of the DFN4 locus within DMD. Genomics 1998; 53:377-82. [PMID: 9799605 DOI: 10.1006/geno.1998.5538] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
X-linked inherited hearing impairment is a group of heterogeneous disorders accounting for less than 2% of hereditary hearing loss. DFN4, a sex-linked hearing impairment associated with profound sensorineural hearing loss, has been previously mapped to Xp21.2, a region containing the DMD locus. We have identified a family from Turkey with deafness in which the disease maps to and refines the DFN4 locus. In contrast to the previous family, the crossover points are entirely within the DMD locus. Two-point lod score analysis for the markers DXS 997, DXS 1214, and DXS 1219 showed a lod score of 2. 59. 5' and 3' crossovers were between DMD 44 and DXS 1219 and between DXS 1214 and DXS 985, respectively, suggesting that DFN4 is either an allele of DMD or a mutation in a DMD nested gene. The restriction of the DFN4 locus to DMD suggests that dystrophin may play an important role in hearing.
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Affiliation(s)
- M H Pfister
- Department of Otolaryngology, University of Tübingen, Tübingen, Germany
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