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Congenital myopathy 4B, autosomal recessive(CMYP4B)

MedGen UID:
1840525
Concept ID:
C5829889
Disease or Syndrome
Synonyms: Nemaline myopathy 1, autosomal dominant or recessive; Nemaline myopathy caused by mutation in the tropomyosin 3 gene
 
Gene (location): TPM3 (1q21.3)
 
Monarch Initiative: MONDO:0012239
OMIM®: 609284

Definition

Congenital myopathy-4B (CMYP4B) is an autosomal recessive disorder of the skeletal muscle characterized by the onset of muscle weakness in infancy or early childhood. The severity and pattern of muscle weakness varies, but most affected individuals show congenital contractures, delayed motor development, hypotonia, generalized muscle weakness, and weakness of the proximal limb muscles and neck muscles, resulting in difficulty walking or inability to walk. Affected individuals have respiratory insufficiency due to muscle weakness, which may be life-threatening. Other common features include myopathic facies, chest deformities, distal joint laxity, and scoliosis. Variable histologic findings on skeletal muscle biopsy are observed, including nemaline rods, type 1 fiber predomination, and centralized nuclei (Tan et al., 1999; Lehtokari et al., 2008). For a discussion of genetic heterogeneity of congenital myopathy, see CMYP1A (117000). [from OMIM]

Clinical features

From HPO
Pes cavus
MedGen UID:
675590
Concept ID:
C0728829
Congenital Abnormality
An increase in height of the medial longitudinal arch of the foot that does not flatten on weight bearing (i.e., a distinctly hollow form of the sole of the foot when it is bearing weight).
Distal lower limb muscle weakness
MedGen UID:
324514
Concept ID:
C1836450
Finding
Reduced strength of the distal musculature of the legs.
Shoulder girdle muscle atrophy
MedGen UID:
339837
Concept ID:
C1847766
Finding
Amyotrophy affecting the muscles of the shoulder girdle.
Dysphagia
MedGen UID:
41440
Concept ID:
C0011168
Disease or Syndrome
Difficulty in swallowing.
Motor delay
MedGen UID:
381392
Concept ID:
C1854301
Finding
A type of Developmental delay characterized by a delay in acquiring motor skills.
Scoliosis
MedGen UID:
11348
Concept ID:
C0036439
Disease or Syndrome
The presence of an abnormal lateral curvature of the spine.
Proximal muscle weakness
MedGen UID:
113169
Concept ID:
C0221629
Finding
A lack of strength of the proximal muscles.
Neck muscle weakness
MedGen UID:
66808
Concept ID:
C0240479
Finding
Decreased strength of the neck musculature.
Flexion contracture
MedGen UID:
83069
Concept ID:
C0333068
Anatomical Abnormality
A flexion contracture is a bent (flexed) joint that cannot be straightened actively or passively. It is thus a chronic loss of joint motion due to structural changes in muscle, tendons, ligaments, or skin that prevents normal movement of joints.
Generalized muscle weakness
MedGen UID:
155433
Concept ID:
C0746674
Sign or Symptom
Generalized weakness or decreased strength of the muscles, affecting both distal and proximal musculature.
Facial diplegia
MedGen UID:
322796
Concept ID:
C1836003
Finding
Facial diplegia refers to bilateral facial palsy (bilateral facial palsy is much rarer than unilateral facial palsy).
Distal lower limb amyotrophy
MedGen UID:
324515
Concept ID:
C1836451
Disease or Syndrome
Muscular atrophy of distal leg muscles.
Pectus excavatum
MedGen UID:
781174
Concept ID:
C2051831
Finding
A defect of the chest wall characterized by a depression of the sternum, giving the chest ("pectus") a caved-in ("excavatum") appearance.
Nemaline bodies
MedGen UID:
814369
Concept ID:
C3808039
Finding
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.
EMG: myopathic abnormalities
MedGen UID:
867362
Concept ID:
C4021726
Pathologic Function
The presence of abnormal electromyographic patterns indicative of myopathy, such as small-short polyphasic motor unit potentials.
Respiratory insufficiency
MedGen UID:
11197
Concept ID:
C0035229
Pathologic Function
Impairment of gas exchange within the lungs secondary to a disease process, neoplasm, or trauma, possibly resulting in hypoxia, hypercarbia, or both, but not requiring intubation or mechanical ventilation. Patients are normally managed with pharmaceutical therapy, supplemental oxygen, or both.
High palate
MedGen UID:
66814
Concept ID:
C0240635
Congenital Abnormality
Height of the palate more than 2 SD above the mean (objective) or palatal height at the level of the first permanent molar more than twice the height of the teeth (subjective).
Long face
MedGen UID:
324419
Concept ID:
C1836047
Finding
Facial height (length) is more than 2 standard deviations above the mean (objective); or, an apparent increase in the height (length) of the face (subjective).
Narrow face
MedGen UID:
373334
Concept ID:
C1837463
Finding
Bizygomatic (upper face) and bigonial (lower face) width are both more than 2 standard deviations below the mean (objective); or, an apparent reduction in the width of the upper and lower face (subjective).

Professional guidelines

Curated

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

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