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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 …