<unk>  (SMAX2,<unk> LSMA), also known as arthrogryposis multiplex congenita<unk><unk>  type 1 (AMCX1), is a rare neurological disorder involving death of motor neurons in the anterior horn of spinal cord resulting in generalised muscle wasting (atrophy). The disease is caused by a mutation in UBA1 gene and is passed in an<unk><unk>  recessive manner by carrier mothers to affected sons. Affected babies have general muscle weakness, weak cry and floppy limbs; consequently, the condition is usually apparent at or even before birth. Symptoms resemble the more severe forms of the more common spinal muscular atrophy (SMA); however, SMAX2 is caused by a different genetic defect and only genetic testing can correctly identify the disease. The disorder is usually fatal in infancy or early childhood due to progressive respiratory failure, although survival into teenage years has been reported. As with many genetic disorders, there is no known cure to SMAX2. Appropriate palliative care may be able to increase quality of life and extend lifespan.
X-linked spinal muscular atrophy type 2
Jokela type spinal muscular atrophy
Fukuyama congenital muscular dystrophy
Distal spinal muscular atrophy type 2
Ullrich congenital muscular dystrophy
Distal spinal muscular atrophy type 1
Madras motor neuron disease
Becker muscular dystrophy