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Nemaline myopathy 6(NEM6)

MedGen UID:
Concept ID:
Disease or Syndrome
Synonyms: NEM6; Nemaline myopathy 6, autosomal dominant
Gene (location): KBTBD13 (15q22.31)
Monarch Initiative: MONDO:0012237
OMIM®: 609273


Nemaline myopathy-6 is an autosomal dominant skeletal muscle disorder characterized by childhood onset of slowly progressive proximal muscle weakness, exercise intolerance, and slow movements with stiff muscles. Patients are unable to run or correct themselves from falling over. Histopathologic changes seen on skeletal muscle biopsy include nemaline rods, cores devoid of oxidative enzyme activity, and predominance of hypertrophic type 1 fibers. There is no cardiac or respiratory involvement (summary by Sambuughin et al., 2010). [from OMIM]

Additional description

From MedlinePlus Genetics
Nemaline myopathy is divided into six types. In order of decreasing severity, the types are: severe congenital, Amish, intermediate congenital, typical congenital, childhood-onset, and adult-onset. The types are distinguished by the age when symptoms first appear and the severity of symptoms; however, there is overlap among the various types. The severe congenital type is the most life-threatening. Most individuals with this type do not survive past early childhood due to respiratory failure. The Amish type solely affects the Old Order Amish population of Pennsylvania and is typically fatal in early childhood. The most common type of nemaline myopathy is the typical congenital type, which is characterized by muscle weakness and feeding problems beginning in infancy. Most of these individuals do not have severe breathing problems and can walk unassisted. People with the childhood-onset type usually develop muscle weakness in adolescence. The adult-onset type is the mildest of all the various types. People with this type usually develop muscle weakness between ages 20 and 50.

Nemaline myopathy is a disorder that primarily affects skeletal muscles, which are muscles that the body uses for movement. People with nemaline myopathy have muscle weakness (myopathy) throughout the body, but it is typically most severe in the muscles of the face; neck; trunk; and other muscles close to the center of the body (proximal muscles), such as those of the upper arms and legs. This weakness can worsen over time. Affected individuals may have feeding and swallowing difficulties, foot deformities, abnormal curvature of the spine (scoliosis), and joint deformities (contractures). Most people with nemaline myopathy are able to walk, although some affected children may begin walking later than usual. As the condition progresses, some people may require wheelchair assistance. In severe cases, the muscles used for breathing are affected and life-threatening breathing difficulties can occur.  https://medlineplus.gov/genetics/condition/nemaline-myopathy

Clinical features

From HPO
Exercise intolerance
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A functional motor deficit where individuals whose responses to the challenges of exercise fail to achieve levels considered normal for their age and gender.
Limb muscle weakness
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Reduced strength and weakness of the muscles of the arms and legs.
Gait disturbance
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The term gait disturbance can refer to any disruption of the ability to walk. In general, this can refer to neurological diseases but also fractures or other sources of pain that is triggered upon walking. However, in the current context gait disturbance refers to difficulty walking on the basis of a neurological or muscular disease.
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Disease or Syndrome
A disorder of muscle unrelated to impairment of innervation or neuromuscular junction.
Muscle stiffness
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Sign or Symptom
A condition in which muscles cannot be moved quickly without accompanying pain or spasm.
Difficulty climbing stairs
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Reduced ability to climb stairs.
Skeletal muscle atrophy
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Pathologic Function
The presence of skeletal muscular atrophy (which is also known as amyotrophy).
Difficulty running
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Reduced ability to run.
Neck flexor weakness
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Weakness of the muscles involved in neck flexion (sternocleidomastoid, longus capitus, longus colli, and scalenus anterior).
Nemaline bodies
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Nemaline rods are abnormal bodies that can occur in skeletal muscle fibers. The rods can be observed on histological analysis of muscle biopsy tissue or upon electron microscopy, where they appear either as extensions of sarcomeric Z-lines, in random array without obvious attachment to Z-lines (often in areas devoid of sarcomeres) or in large clusters localized at the sarcolemma or intermyofibrillar spaces.
Elevated circulating creatine kinase concentration
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An elevation of the level of the enzyme creatine kinase (also known as creatine phosphokinase (CK; EC in the blood. CK levels can be elevated in a number of clinical disorders such as myocardial infarction, rhabdomyolysis, and muscular dystrophy.

Professional guidelines


Nowak KJ, Davis MR, Wallgren-Pettersson C, Lamont PJ, Laing NG
Eur J Hum Genet 2012 Jun;20(6) Epub 2012 Apr 18 doi: 10.1038/ejhg.2012.70. PMID: 22510848Free PMC Article

Recent clinical studies

Clinical prediction guides

Bouman K, Küsters B, De Winter JM, Gillet C, Van Kleef ESB, Eshuis L, Brochier G, Madelaine A, Labasse C, Boulogne C, Van Engelen BGM, Ottenheijm CAC, Romero NB, Voermans NC, Malfatti E
J Neuropathol Exp Neurol 2021 Mar 22;80(4):366-376. doi: 10.1093/jnen/nlab012. PMID: 33693846

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