Arthrogryposis multiplex congenita-whistling face syndrome

Arthrogryposis multiplex congenita-whistling face syndrome, also known as Freeman-Sheldon syndrome (FSS) or distal arthrogryposis type 2A (DA2A) or craniocarpotarsal dystrophy, is a rare genetic disorder characterized by the combination of multiple joint contractures (arthrogryposis) and distinctive facial features. The hallmark facial appearance includes a very small, pursed mouth that resembles a whistling expression, prominent nasolabial folds, a small nose, deep-set eyes, and an H-shaped dimpling of the chin. The condition primarily affects the musculoskeletal system, with contractures most commonly involving the hands (clenched fists with ulnar deviation), feet (clubfoot or talipes equinovarus), and other joints. Patients may also experience restricted movement of the shoulders, elbows, hips, and knees. Additional features can include short stature, scoliosis or kyphosis, difficulty swallowing and feeding (particularly in infancy), speech difficulties due to the small oral opening (microstomia), and respiratory complications. Intelligence is typically normal, though developmental delays may occur secondary to physical limitations. Some patients experience malignant hyperthermia susceptibility during anesthesia, which is an important consideration for surgical planning. Treatment is multidisciplinary and primarily supportive. Surgical interventions may be needed to correct joint contractures, clubfoot, scoliosis, and to improve oral opening. Physical and occupational therapy are essential to maximize joint mobility and functional independence. Speech therapy may be beneficial for those with communication difficulties. Craniofacial surgery can address the restrictive facial features. Genetic counseling is recommended for affected families. The condition is caused by mutations in the MYH3 gene, which encodes embryonic myosin heavy chain, playing a critical role in fetal muscle development.

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