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Start free with EleplanAlpha-B crystallin-related late-onset myopathy
ORPHA:399058Disease
Also called Alpha-B crystallin-related late-onset distal myopathy · Late-onset distal crystallinopathy
What it is
A rare, genetic, alpha-crystallinopathy disease characterized by adult-onset myofibrillar myopathy, variably associated with cardiomyopathy and/or posterior polar cataracts. Patients typically present progressive proximal and distal muscle weakness and wasting of lower and upper limbs, often with velopharyngeal involvement including dysphagia, dysphonia and ventilatory insufficiency. Electromyography shows myopathic features and muscle biopsy reveals myofibrillar myopathy changes.
Key facts
- Prevalence
- <1 / 1 000 000
- Age of onset
- Adult
- Inheritance
- Autosomal dominant
- Classified as
- Disease
Prevalence figures describe populations, not individuals, and are often estimates from a single study. Where the figure is an incidence or a birth prevalence, it says so.
Signs and symptoms
Common30–79%
12- Abnormal circulating creatine kinase concentration
- Accumulation of muscle fiber desmin
- Autophagic vacuoles
- Axial muscle weakness
- EMG: myopathic abnormalitiesDiagnostic criterion
- Foot dorsiflexor weakness
- Hyporeflexia
- Increased variability in muscle fiber diameter
- Limb-girdle muscle weakness
- Muscle fiber inclusion bodies
- Neck muscle weakness
- Posterior capsular cataractDiagnostic criterion
These ranges are how often a sign appears across everyone diagnosed, not a prediction for one person — most people have some of these and not others. Orphanet also records findings that are specifically absent in this disease; those are in the data but not listed here.
Gene
ICD-10 codes
ICD-10 has no distinct code for most rare diseases, so many are filed under the nearest available one. A shared code identifies the group, not this disease — the ORPHAcode above is what identifies it.
Related health topics
Reached through the ICD-10 categories this disease is filed under, so these describe the broader group rather than this disease specifically.
Benefit programs to look at
Programs whose eligibility touches the same ICD-10 categories. Eligibility is decided by the administering agency, never by this page.
Cross-references
Orphadata Science: Free access data from Orphanet. © INSERM 1999. Data version 2026-06-23. Available under CC BY 4.0. This is a reference, not medical advice.
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