SMA-LED is a rarer form of SMA that begins in infancy or early childhood and progresses slowly. Like 5q SMA, SMA-LED affects the nerve cells called motor neurons. These cells transmit electrical signals from the spinal cord to muscles for voluntary muscle contraction.

SMA-LED causes motor neurons to malfunction, resulting in weakness in leg muscles, which is most severe in the thigh muscles (quadriceps). Children and adults often have a ‘waddling’ or unsteady walk and have difficulty climbing stairs and getting up from sitting.

There is only limited information about SMA-LED because it is so rare, but your or your child’s medical team will be able to discuss how it affects you / your child and how to manage symptoms for maximum comfort and quality of life.

SMA-LED has been linked to mutations in two different genes:

• For further information about the DYNC1H11-2 gene >
• For further information about the BICD23-6 gene >

SMA-LED has an Autosomal Dominant inheritance pattern, which means that only one faulty gene copy passed on from a parent with the condition is enough to cause the disease.

Though not a substitute for professional medical advice, MedlinePlus is a service of the US National Library of Medicine (NLM). It provides more information about SMA-LED >

SMA UK

• Phone: 01789 267520
• Email: office@smauk.org.uk
• Website: www.smauk.org.uk

Provides information and support for anyone in the UK affected by any form of SMA.

Contact 

• Phone: 0808 808 3555
• Website: www.contact.org.uk

Provides information and support for families with children with a disability.

1. Harms et al. (2012) Mutations in the tail domain of DYNC1H1 cause dominant spinal muscular atrophy. Neurology 78: 1714-1720.
2. https://www.omim.org/entry/158600 (last accessed 21st August 2024)
3. Neveling et al. (2013) Mutations in BICD2, which encodes a golgin and important motor adaptor, cause congenital autosomal-dominant spinal muscular atrophy. Am J Hum Genet 92: 946-954.
4. Peeters et al. (2013) Molecular defects in the motor adaptor BICD2 cause proximal spinal muscular atrophy with autosomal-dominant inheritance. Am J Hum Genet 92: 955-964.
5. Oates et al. (2013) Mutations in BICD2 cause dominant congenital spinal muscular atrophy and hereditary spastic paraplegia. Am J Hum Genet 92: 965-973.
6. https://www.omim.org/entry/615290 (last accessed 21st August 2024)