Synonyms: SMAX2 | Spinal muscular atrophy with arthrogryposis | X-linked distal arthrogryposis multiplex congenita | X-linked spinal muscular atrophy type 2
A rare form of spinal muscular atrophy characterized by the neonatal onset of severe hypotonia areflexia profound weakness multiple congenital contractures facial dysmorphic features (myopathic face with open tent-shaped mouth) cryptorchidism and mild skeletal abnormalities (i.e. kyphosis scoliosis) that is often preceded by polyhydramnios and reduced fetal movements in utero and followed by bone fractures shortly after birth. Muscle weakness is progressive and chest muscle involvement eventually leads to ventilatory insufficiency and respiratory failure.
Data from Orphanet are used to provide information on a disease's name, synonym(s), and overview. Reference: Access aggregated data from Orphanet at Orphadata. Orphadata: Free access data from Orphanet. © INSERM 1999. Available on http://www.orphadata.org. Data version March 2026
Newly diagnosed with
Infantile-onset X-linked spinal muscular atrophy?
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Advocacy Organizations
Association Aux Pas du Coeur – Côte d’ivoire
Our organization wants to raise awareness and recognition of rare diseases in Ivory Coast. Our mission is to: Raise awareness and campaign to help with the diagnosis and free therapeutic care of patients. Request and/or contribute to actions relating to the training of the medical profession to be able to make a final diagnosis and ensure continuous monitoring of patients easily.
Charcot-Marie-Tooth Association
Our mission … to support the development of new treatments for CMT, to improve the quality of life for people with CMT, and, ultimately, to find a cure. Our vision … a world without CMT. CMTA was started by patients in 1986, and to this day is powered by a community of patients who are engaged in helping carry out and support our mission.
Fundacion Powerchair Football Argentina
To develop Powerchair Football in Argentina in order to integrate people with motor disabilities (SMA, Duchenne muscular dystrophy, Achondroplasia, Rare Diseases) into sports practice and to promote their social inclusion, based on empowerment, independence, and the creation of new bonds and friendships.
Neuromuscular Disease Foundation
The Neuromuscular Disease Foundation's (NDF) mission is to enhance the quality of the lives of people living with GNE Myopathy (also known as HIBM) through advocacy, education, outreach, and funding clinical research focused on treatments and a cure.
ZC4H2 Research Foundation
Our Mission: The purpose of the ZC4H2 Research Foundation is to support the development of viable therapies and standards of clinical care for the treatment of ZC4H2 Associated Rare Disorders (ZARD), and to be an information and support network for the ZARD community. We advocate through research, awareness, and support. For more information, please visit https://www.zc4h2foundation.org.
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Clinical Trials
For a list of clinical trials in this disease area, please click here.