The EXPLAIN Study: Exploring Arthrogryposis Multiplex Congenita in Adults in Norway - A Description of Demographic, Medical, and Neurological Findings.

Arthrogryposis Multiplex Congenita (AMC) encompasses several hundred conditions with diverse genetic, pathophysiological, and clinical origins. The overarching EXPLAIN study explores underlying causes and implications of AMC and represents the largest clinical cohort of adults with AMC reported to date. This part of the EXPLAIN study aims to describe demographic, medical, and neurological findings in adults with AMC in Norway. A complete social, medical, and surgical history was therefore obtained, and the clinical examination comprised phenotype descriptions, anthropometry, neurological and neurophysiological tests, and blood analyses. Seventy-two adults (44 women), 18 to 80 years, were included. 57% reported neurological disease or symptoms. Spinal or truncal involvement was observed in 63%, and craniofacial malformations were observed in 36%. Central nervous system involvement frequently manifested as sensory hearing impairment (26%) and ophthalmoplegia (18%). Peripheral features included axial muscle weakness (53%), areflexia (44%), and hypotonia (40%). Neurogenic changes were identified in 61% of electrophysiological studies, with 31% showing sensory-motor neuropathy. Medical follow-up was required in 75%. This study highlights significant phenotypic variability in socioeconomic factors, medical comorbidities, and clinical presentation of AMC. The prevalence of musculoskeletal and neurological variations emphasizes the need for multidisciplinary care throughout life.