IDC-10: ICD-10: G71.2
Estimated occurrence2:100,000 live births.
The main symptoms of nemaline myopathy are muscle weakness and low muscle tone. The severity of symptoms varies between different people with the disease, from severe muscle weakness and low muscle tone in most parts of the body already at birth, to a milder form that first occurs in adulthood. The disease is divided into different forms depending on the age of onset and degree of severity: severe, medium-severe and the classic congenital form, the childhood form and the adult form. Muscle weakness is not usually progressive or only increases very slowly. Breathing may be affected and sometimes there is a need for some form of respiratory support. Children often have hyperflexible joints, but limitations on joint flexibility may occur as they get older.
Sucking and swallowing difficulties are common among children who have low muscle tone at birth. Weakened facial musculature with impaired facial expression, chewing and swallowing difficulties, reduced saliva control and speech impairments are also common. Muscle weakness can affect growth of the facial skeleton, sometimes leading to malocclusion. High and narrow palate occurs sometimes.
Advice on follow-up and treatment
- Early contact with dental services for intensified prophylactic care and oral hygiene information is essential.
- Regular check-ups of dental and jaw development. Orthodontist should be consulted when needed.
- Feeding and swallowing difficulties are investigated and treated by a specialist team at the hospital or multidisciplinary treatment centre.
- Orofacial therapy and oral motor skills training and stimulation in cases of difficulties with eating, speech or drooling may be relevant.
- There is an increased risk of malignant hyperthermia when administering anaesthetics to people with mutations in the RYR1 gene.