U.S. flag

An official website of the United States government

Format

Send to:

Choose Destination

Congenital myasthenic syndrome 10(CMS1B, FORMERLY; CMS10; LGM, FORMERLY)

MedGen UID:
376880
Concept ID:
C1850792
Disease or Syndrome
Synonyms: AGRN-Related Congenital Myasthenic Syndrome; DOK7-Related Congenital Myasthenic Syndrome; Myasthenia, limb-girdle, familial
 
Gene (location): DOK7 (4p16.3)
 
Monarch Initiative: MONDO:0009690
OMIM®: 254300

Definition

Congenital myasthenic syndromes (CMS) are a group of inherited disorders affecting the neuromuscular junction (NMJ). Patients present clinically with onset of variable muscle weakness between infancy and adulthood. These disorders have been classified according to the location of the defect: presynaptic, synaptic, and postsynaptic. CMS10 is an autosomal recessive CMS resulting from a postsynaptic defect affecting endplate maintenance of the NMJ. Patients present with limb-girdle weakness in the first decade. Treatment with ephedrine or salbutamol may be beneficial; cholinesterase inhibitors should be avoided (summary by Engel et al., 2015). For a discussion of genetic heterogeneity of CMS, see CMS1A (601462). [from OMIM]

Additional description

From MedlinePlus Genetics
Congenital myasthenic syndrome is a group of conditions characterized by muscle weakness (myasthenia) that worsens with physical exertion. The muscle weakness typically begins in early childhood but can also appear in adolescence or adulthood. Facial muscles, including muscles that control the eyelids, muscles that move the eyes, and muscles used for chewing and swallowing, are most commonly affected. However, any of the muscles used for movement (skeletal muscles) can be affected in this condition. Due to muscle weakness, affected infants may have feeding difficulties. Development of motor skills such as crawling or walking may be delayed. The severity of the myasthenia varies greatly, with some people experiencing minor weakness and others having such severe weakness that they are unable to walk.

Some individuals have episodes of breathing problems that may be triggered by fevers or infection. Severely affected individuals may also experience short pauses in breathing (apnea) that can lead to a bluish appearance of the skin or lips (cyanosis).  https://medlineplus.gov/genetics/condition/congenital-myasthenic-syndrome

Clinical features

From HPO
Waddling gait
MedGen UID:
66667
Concept ID:
C0231712
Finding
Weakness of the hip girdle and upper thigh muscles, for instance in myopathies, leads to an instability of the pelvis on standing and walking. If the muscles extending the hip joint are affected, the posture in that joint becomes flexed and lumbar lordosis increases. The patients usually have difficulties standing up from a sitting position. Due to weakness in the gluteus medius muscle, the hip on the side of the swinging leg drops with each step (referred to as Trendelenburg sign). The gait appears waddling. The patients frequently attempt to counteract the dropping of the hip on the swinging side by bending the trunk towards the side which is in the stance phase (in the German language literature this is referred to as Duchenne sign). Similar gait patterns can be caused by orthopedic conditions when the origin and the insertion site of the gluteus medius muscle are closer to each other than normal, for instance due to a posttraumatic elevation of the trochanter or pseudarthrosis of the femoral neck.
Fatigable weakness
MedGen UID:
451076
Concept ID:
C0947912
Disease or Syndrome
A type of weakness that occurs after a muscle group is used and lessens if the muscle group has some rest. That is, there is diminution of strength with repetitive muscle actions.
Easy fatigability
MedGen UID:
373253
Concept ID:
C1837098
Finding
Increased susceptibility to fatigue.
Bulbar palsy
MedGen UID:
898626
Concept ID:
C4082299
Disease or Syndrome
Bulbar weakness (or bulbar palsy) refers to bilateral impairment of function of the lower cranial nerves IX, X, XI and XII, which occurs due to lower motor neuron lesion either at nuclear or fascicular level in the medulla or from bilateral lesions of the lower cranial nerves outside the brain-stem. Bulbar weakness is often associated with difficulty in chewing, weakness of the facial muscles, dysarthria, palatal weakness and regurgitation of fluids, dysphagia, and dysphonia.
Muscle spasm
MedGen UID:
52431
Concept ID:
C0037763
Sign or Symptom
Sudden and involuntary contractions of one or more muscles.
Gowers sign
MedGen UID:
65865
Concept ID:
C0234182
Finding
A phenomenon whereby patients are not able to stand up without the use of the hands owing to weakness of the proximal muscles of the lower limbs.
Weakness of facial musculature
MedGen UID:
98103
Concept ID:
C0427055
Disease or Syndrome
Reduced strength of one or more muscles innervated by the facial nerve (the seventh cranial nerve).
Axial muscle weakness
MedGen UID:
334472
Concept ID:
C1843697
Finding
Reduced strength of the axial musculature (i.e., of the muscles of the head and neck, spine, and ribs).
Distal amyotrophy
MedGen UID:
338530
Concept ID:
C1848736
Disease or Syndrome
Muscular atrophy affecting muscles in the distal portions of the extremities.
Proximal amyotrophy
MedGen UID:
342591
Concept ID:
C1850794
Disease or Syndrome
Amyotrophy (muscular atrophy) affecting the proximal musculature.
Reduced vital capacity
MedGen UID:
141657
Concept ID:
C0476408
Finding
An abnormal reduction on the vital capacity, which is defined as the total lung capacity (volume of air in the lungs at maximal inflation) less the residual volume (i.e., volume of air in the lungs following maximal exhalation) of the lung.
Respiratory insufficiency due to muscle weakness
MedGen UID:
812797
Concept ID:
C3806467
Finding
Anti-acetylcholine receptor antibody positivity
MedGen UID:
868186
Concept ID:
C4022578
Finding
The presence of autoantibodies (immunoglobulins) in the blood circulation that react against neuromuscular junction acetylcholine receptors.
Mildly elevated creatine kinase
MedGen UID:
342469
Concept ID:
C1850309
Finding
Tongue atrophy
MedGen UID:
66828
Concept ID:
C0241423
Finding
Wasting of the tongue.
Decreased fetal movement
MedGen UID:
68618
Concept ID:
C0235659
Finding
An abnormal reduction in quantity or strength of fetal movements.
Ptosis
MedGen UID:
2287
Concept ID:
C0005745
Disease or Syndrome
The upper eyelid margin is positioned 3 mm or more lower than usual and covers the superior portion of the iris (objective); or, the upper lid margin obscures at least part of the pupil (subjective).
Ophthalmoparesis
MedGen UID:
155551
Concept ID:
C0751401
Sign or Symptom
Ophthalmoplegia is a paralysis or weakness of one or more of the muscles that control eye movement.

Professional guidelines

PubMed

Özsoy Ö, Cinleti T, Günay Ç, Sarıkaya Uzan G, Giray Bozkaya Ö, Çağlayan AO, Hız Kurul S, Yiş U
Acta Neurol Belg 2023 Dec;123(6):2325-2335. Epub 2023 Sep 1 doi: 10.1007/s13760-023-02370-3. PMID: 37656362

Supplemental Content

Table of contents

    Clinical resources

    Practice guidelines

    • PubMed
      See practice and clinical guidelines in PubMed. The search results may include broader topics and may not capture all published guidelines. See the FAQ for details.

    Recent activity

    Your browsing activity is empty.

    Activity recording is turned off.

    Turn recording back on

    See more...