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Mutations in the HSJ1 (Heat-Shock Protein J1) gene, also called DNAJB2 (DnaJ (Hsp40) homologue, subfamily B, member 2), have been recently described as a cause of hereditary neuropathies. The HSJ1 c.352+1G>A mutation in homozygote state has been reported as the causative mutation in a single family with autosomal recessive distal hereditary motor neuropathy (dHMN).1 Since then, two other families with different HSJ1 mutations have been described: one with a dHMN phenotype and the other with a Charcot-Marie-Tooth disease type 2 (CMT2) phenotype.2
We identified the HSJ1 c.352+1G>A mutation in 10 patients who underwent long-lasting follow-up. We describe their phenotype and clinical evolution.
Patients and methods
Ten patients from five different Spanish families had been diagnosed with dHMN or CMT2 at two tertiary referral centres in Spain between 1976 and 2014. They all underwent neurological examination and electrophysiological studies using standard techniques.3 Regular follow-up was performed in all cases and repeated electrophysiological studies were carried out in some patients.
All the families carried the HSJ1 c.352+1G>A homozygote pathogenic sequence variation. Family 1 was diagnosed by exome sequencing. Families 2 and 4 were diagnosed using a gene panel for genetic testing of CMT and dHMN. Families 3 and 5 were identified by mutational screening of the HSJ1 c.352+1G>A change, carried out in 52 patients from our registry, with autosomal recessive dHMN or CMT2, who still had no molecular diagnosis. In all cases, mutation was confirmed by Sanger sequencing and a segregation analysis was performed whenever possible.
All the patients and relatives included in the present study signed informed consent. The research protocols were approved by the respective institutional boards of the Ethics Committee …
Contributors MF designed the study, participated in clinical data acquisition and interpretation, and wrote and edited the manuscript. MJC participated in electrophysiological studies and interpretation. JJV participated in clinical data acquisition and interpretation, and critically revised the manuscript. CM-I participated in clinical data acquisition and interpretation. FP critically revised the manuscript. JFV-C participated in clinical data acquisition. VL participated in genetic analysis and interpretation. CE participated in genetic analysis and interpretation. TS designed and supervised the study, participated in clinical data acquisition and interpretation, and critically revised the manuscript.
Funding This collaborative joint project is awarded by IRDiRC and funded by the Instituto de Salud Carlos III (ISCIII)-Subdirección General de Evaluación y Fomento de la Investigación within the framework of the National R+D+I Plan (grants number IR11/TREAT-CMT to TS, CM-I, FP and CE; PI12/0946 to TS), the Fundación para la Investigación del Hospital Universitari La Fe (2015/0085, PI TS). The Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER) is an initiative of the ISCIII. MF received a grant by Instituto de Investigación La Fe (2015/0085, PI TS). CM-I is funded by an IRDiRC grant (IR11/TREAT-CMT). FP is funded by an IRDiRC grant (IR11/TREAT-CMT). JFV-C is funded by an Instituto de Investigación La Fe grant (2013/0332). CE is funded by grants from the ISCIII (CPII14/00002 and PI12/00453) and IRDiRC (IR11/TREAT-CMT). CE has a ‘Miguel Servet’ contract funded by the ISCIII and the Research Centre Príncipe Felipe (CIPF). TS is funded by grants from the ISCIII and IRDiRC (IR11/TREAT-CMT and PI12/0946).
Competing interests None declared.
Ethics approval Institutional Review Board of the Ethics Committee of the Hospital Universitari I Politècnic La Fe and the Institutional Review Board of the Ethics Committee of the Hospital Universitario Virgen del Rocío.
Provenance and peer review Not commissioned; externally peer reviewed.