Autosomal Recessive Limb-Girdle Muscular Dystrophy Caused by ANO5 Mutation

Other names
Types
Causes
Common symptoms
Diagnostic tests
Non-pharmacological treatments (therapies & other care)
Drug treatments
Dietary molecular supplements
Immunity-booster/regenerative/stem-cell” drugs
Surgeries
Preventions
When to see doctors (red flags)
What to eat” and “what to avoid
FAQs

Autosomal recessive limb-girdle muscular dystrophy caused by ANO5 mutation is a genetic muscle disease. It happens when a person inherits two faulty copies of the ANO5 gene (one from each parent). This gene makes a protein that helps muscle-cell membranes heal after tiny injuries that happen during normal movement. When the ANO5 protein does not work well, the muscle cell membrane does not repair itself properly. Over time, muscle fibers break down faster than the body can fix them. This leads to slowly progressive weakness in the muscles around the hips, thighs, shoulders, and upper arms—the “limb-girdle” areas. Symptoms often start in adulthood, most commonly in the 30s to 50s, but the range is wide. Some people have muscle pain, calf enlargement, or repeated episodes of dark urine after heavy exercise due to muscle breakdown (rhabdomyolysis). Others may be well for years with only a high blood level of muscle enzymes (high CK) and no weakness yet. NCBI+2Orpha+2

ANO5-related limb-girdle muscular dystrophy is an inherited muscle condition that weakens the shoulders and hips (the “limb-girdle” muscles). Symptoms usually start in teens to adulthood and may include exercise-induced pain, high blood levels of muscle enzyme (CK), and slowly progressive weakness; some people get calf muscle enlargement or episodes of rhabdomyolysis. ANO5 makes a protein (anoctamin-5/TMEM16E) that helps repair the muscle cell membrane; mutations disrupt repair, so everyday stress damages muscle fibers over time. There is currently no curative medicine, so care focuses on safe exercise, contracture prevention, pain control, and monitoring of heart and breathing just in case. MDPI+1

Why this happens at the cell level: ANO5 belongs to the “anoctamin/TMEM16” family. In skeletal muscle, ANO5 is involved in phospholipid scrambling and helps direct annexin proteins to wounds in the cell membrane. Without ANO5, injured muscle fibers cannot organize repair proteins correctly, and the membrane stays leaky. This repeated leak-repair failure is a key reason for progressive muscle damage. RUPress+1

Other names

LGMDR12 or LGMD R12 anoctamin-5-related (the current Limb-Girdle Muscular Dystrophy naming system for a recessive form). PMC
ANO5-related muscle disease (an umbrella term because the same gene can cause several muscle phenotypes). NCBI
Anoctamin-5 myopathy / anoctaminopathy-5. PMC
Miyoshi-like distal myopathy type 3 (MMD3) when the main weakness is in the calves and distal legs. NCBI+1

Types

1) Classic limb-girdle pattern (LGMDR12):
Slow, mainly proximal weakness (hips, thighs first; later shoulders). Walking, climbing stairs, and rising from chairs get harder over years. Calf enlargement can occur. Some have thigh muscle wasting, especially quadriceps. Adult onset is common. Heart involvement is uncommon but screening is advised. Orpha+1

2) Distal (Miyoshi-like) pattern (MMD3):
Weakness starts in the calves and feet. Running and tip-toe walking become difficult. Cramps and exercise-induced pain are frequent. Onset is often in early–mid adulthood. NCBI+1

3) HyperCKemia/myalgia phenotype:
Some people have no noticeable weakness for years but have high CK on blood tests, muscle pain with exercise, or occasional rhabdomyolysis. This can be the earliest sign before weakness appears. NCBI+2Frontiers+2 NCBI

Causes

Because this is a monogenic (single-gene) disease, the core cause is biallelic pathogenic variants in ANO5. The list below explains root mechanisms, variant contexts, and real-world triggers that can bring on or worsen muscle injury in people who carry ANO5 defects.

Biallelic pathogenic ANO5 variants (autosomal recessive inheritance) – two faulty copies are necessary for disease. NCBI
Loss of sarcolemmal (muscle membrane) repair – the basic pathophysiology leading to fiber necrosis over time. RUPress
Defective phospholipid scrambling – a needed step for membrane resealing after micro-tears. PMC
Annexin trafficking defects to wound sites – poor assembly of annexin “repair caps” in ANO5 loss. RUPress
Founder variants in certain populations – some regions have common ANO5 variants, increasing local incidence (for example, European clusters), although specifics vary by study. PMC
High-intensity eccentric exercise – larger membrane stress may precipitate pain, high CK, or rhabdomyolysis. NCBI+1
Prolonged unaccustomed activity or military-style training – similar stress-injury mechanism; watch for dark urine and severe muscle pain. ejcrim.com
Intercurrent infections with fever/dehydration – can increase risk of muscle breakdown in susceptible muscles. (Inference consistent with rhabdomyolysis care in genetic myopathies.)
Statin exposure – case reports suggest statins may worsen muscle symptoms in some genetic myopathies, including ANO5; risk-benefit requires clinician review. ejcrim.com
Electrolyte disturbances (e.g., low potassium) – can aggravate cramps and weakness in myopathies in general. (General neuromuscular care principle.)
Thyroid dysfunction – thyroid disease can worsen myopathy symptoms; screening is routine in unexplained high CK. (General endocrine-neuromuscular practice.)
Vitamin D deficiency – adds myalgia and weakness; correcting it can improve comfort/function. (General evidence in myopathy populations.)
Prolonged corticosteroid catabolism – long courses can waste muscle; not a standard ANO5 therapy. (General myopathy care.)
Immobilization – deconditioning accelerates weakness; gentle activity helps maintain function. (General rehab principle.)
Inadequate protein/energy intake – insufficient nutrition limits repair capacity. (General rehab/nutrition guidance for myopathies.)
Alcohol binge with dehydration – can raise rhabdomyolysis risk. (General rhabdomyolysis risk factor.)
Heat stress – increases muscle breakdown risk in exertion. (General exertional rhabdomyolysis knowledge.)
Certain anesthetic risks – LGMDs call for careful peri-anesthetic planning (avoid triggers for rhabdomyolysis; plan airway/respiratory assessment). PMC
Coexisting neuromuscular disorders – rare but may worsen outcomes if present. (General principle.)
Aging – sarcopenia adds to inherited weakness over decades. (General geriatric-neuromuscular principle.)

Common symptoms

Trouble climbing stairs or rising from a low seat – early sign of hip and thigh weakness. Orpha
Fatigue in the thighs with walking – proximal muscles tire early in LGMD. NCBI
Waddling or Trendelenburg-type gait – hips drop due to weak gluteal muscles. (LGMD hallmark.)
Difficulty running or jumping – power-dependent tasks become hard as proximal strength falls. NCBI
Calf enlargement (hypertrophy) – calves can look big even while other muscles thin. Orpha
Muscle cramps or aching after activity – membrane injury causes irritability and pain. NCBI
Exercise-induced myalgia or episodes of dark urine (rhabdomyolysis) – signals acute muscle breakdown; urgent hydration and medical review are needed. ejcrim.com
Frequent “charley horses” in calves – common in distal pattern (MMD3). Frontiers
Shoulder weakness later on – raising arms overhead gets harder. NCBI
Thigh muscle wasting (especially quadriceps) – visible thinning can appear over time. Orpha
Falls or near-falls – weak hip stabilizers and fatigue increase risk. (LGMD principle.)
High CK on a routine blood test – sometimes the first clue, even without symptoms yet. NCBI
Stiffness after rest – painful start-up after sitting is common in myopathies. (General myopathy symptom.)
Mild breathing or heart symptoms are uncommon – major cardiomyopathy is not typical, but baseline screening is advised. NCBI
Very slow progression – many people stay mobile for years with tailored activity and monitoring. NCBI

Diagnostic tests

A) Physical examination

Gait observation – doctors watch for a waddling gait or hip drop when you walk; this suggests proximal hip weakness typical of LGMD. PMC
Gowers’-type maneuvers and chair-rise – standing from the floor or a low chair may require using hands to push up, a sign of proximal weakness. (LGMD exam principle.)
Manual muscle testing by muscle group – hip flexors/extensors/abductors and quadriceps often show earlier weakness than hands or forearms. Pattern helps distinguish LGMD from neuropathy. PMC
Calf inspection and palpation – some people with ANO5 have calf hypertrophy; others have calf tenderness after exertion. Orpha
Functional tests (stair count, timed up-and-go, 6-minute walk) – simple timed tests track day-to-day function and change over time. (Standard neuromuscular clinic practice.)

B) “Manual bedside tests of function

Single-leg heel raise / tip-toe test – difficulty standing on tip-toes hints at calf involvement seen in distal ANO5 disease. Orpha
Squat-to-stand repetitions – tracks proximal thigh strength and endurance.
Arm abduction hold – tests shoulder girdle endurance; fatigue suggests progression to upper-girdle weakness. (General LGMD practice.)
Stair ascent/descent test – changes in time or need for rails show functional decline or improvement with rehab. (General rehab tracking.)

C) Laboratory and pathological tests

Serum creatine kinase (CK) – often high (sometimes 5–50× normal) even before weakness; very high during rhabdomyolysis. NCBI
Serum/urine myoglobin during episodes – confirms muscle breakdown in acute myalgias. (Rhabdomyolysis workup.)
Genetic testing of ANO5 – definitive test. Next-generation sequencing panels or whole-genome/exome identify variants; confirming two pathogenic variants establishes the diagnosis. NCBI+1
Variant interpretation with databases – clinicians use curated resources and segregation data to classify variants. (General genetics standard; example frameworks discussed in contemporary reviews.) ScienceDirect
Muscle biopsy (when genetics is inconclusive) – shows myopathic changes: fiber size variation, necrosis/regeneration, sometimes rimmed vacuoles; not always needed now that genetic testing is widely available. NCBI
Routine screening labs – thyroid function, vitamin D, and metabolic panels to rule out contributory factors to symptoms and cramps. (General myopathy care.)

D) Electrodiagnostic tests

Electromyography (EMG) – shows a myopathic pattern (short-duration, low-amplitude motor unit potentials with early recruitment). Nerve conduction studies are usually normal. Useful to exclude neuropathy. PMC
Cardiac rhythm screening (ECG ± Holter) – major cardiomyopathy is not typical, but baseline and periodic checks are prudent in LGMD. NCBI

E) Imaging tests

Muscle MRI of thighs and calves – helpful pattern recognition. In ANO5, radiologists often note selective involvement of adductor magnus, semimembranosus, and biceps femoris, with relative sparing of others early on. Pattern supports the diagnosis and helps choose a biopsy site if needed. PMC
Cardiac ultrasound (echocardiography) – baseline screen even though substantial heart muscle disease is uncommon in ANO5; done to be safe. NCBI
Chest imaging only if symptoms – not routine; used to evaluate breathing issues or other causes of fatigue if they arise. (General LGMD practice.)

Non-pharmacological treatments (therapies & other care)

Note: For every item below, the goals are “protect the membrane, keep muscles active but not over-stressed, avoid rhabdo triggers, and maintain safety and independence.” Your rehab team can customize frequency and intensity.

Education & pacing plan: Learn warning signs (new severe pain, dark urine), schedule activity with rest, hydrate, and avoid “boom-bust” exercise. This reduces membrane stress and rhabdo risk. PMC+1
Hydration strategy: Fluids before/during/after activity; more in heat/illness. Helps limit rhabdomyolysis risk and supports kidney flush-through in minor CK rises. enmc.org
Temperature management: Avoid heavy exertion in hot/humid weather (or use cooling vests/fans). Heat amplifies exertional muscle injury. nmd-journal.com
Personalized aerobic exercise (low-to-moderate): Walking, cycling, or water-based exercise improves stamina without excessive eccentric loads. Progress gradually. LGMD Awareness Foundation
Strength training (gentle, concentric-biased): Light resistance focusing on quality movement; avoid high-force eccentric routines that tear membranes. nmd-journal.com
Flexibility program (short, pain-free holds): Preserve range without overstretching fragile fibers; pay attention to calves and hip flexors. LGMD Awareness Foundation
Balance & falls-prevention: Task-specific balance drills and home safety checks reduce injuries that accelerate deconditioning. LGMD Awareness Foundation
Energy conservation & task modification: Raise chair heights, use hands strategically, break chores into chunks—protects muscles for meaningful activities. LGMD Awareness Foundation
Assistive devices (as needed): Trekking poles, canes, or lightweight braces can reduce fall risk and knee hyperextension from quadriceps weakness. NCBI
Orthotics/ankle-foot braces (individualized): Aid foot clearance and endurance for those with distal involvement. LGMD Awareness Foundation
Occupational therapy for upper-limb endurance: Adaptive strategies for overhead work and self-care to reduce shoulder fatigue. LGMD Awareness Foundation
Nutritional counseling: Adequate protein, total calories, and vitamin D/calcium to support muscle recovery and bone health. LGMD Awareness Foundation
Weight management: Modest weight loss (if needed) lowers strain on weak muscles and joints. LGMD Awareness Foundation
Sleep optimization: Consistent schedule, screen hygiene, and evaluating sleep apnea symptoms improve daytime function. LGMD Awareness Foundation
Pain self-management (heat/ice/massage): Non-drug methods to calm post-activity soreness and allow regular training. LGMD Awareness Foundation
Trigger-avoidance plan: Avoid maximal eccentric workouts, unaccustomed sprints, and heavy lifts to limit membrane micro-injury. PMC
Illness protocol: Reduce exertion when sick, hydrate more, and check urine color; seek care early if pain/weakness surge. enmc.org
Periodic baseline testing: CK trend, strength measures, and fall screens help tune exercise safely. LGMD Awareness Foundation
Genetic counseling: Clarifies inheritance, family testing options, and research trial eligibility. NCBI
Clinical trial engagement: Watch for ANO5 studies or general LGMD trials; contributes to future therapies. PMC

Drug treatments

Important: No medication below is approved to modify ANO5 disease. These can help specific symptoms (pain, cramps, mood, sleep) if your neuromuscular clinician believes they fit your situation. Always balance benefits and risks using the FDA label and your medical history.

Acetaminophen (oral/IV): For mild-to-moderate pain or fever; avoids NSAID GI/bleeding risks; watch cumulative daily dose (max 4,000 mg/day in adults). Common first-line analgesic. FDA Access Data+1
Naproxen/other NSAIDs: For activity-related musculoskeletal pain; carry boxed warnings for GI bleeding and CV risk—use lowest effective dose, shortest time. FDA Access Data+2FDA Access Data+2
Gabapentin: For neuropathic-type pain features or sleep when appropriate; dose titration required; dizziness/somnolence possible. FDA Access Data+1
Duloxetine: For chronic musculoskeletal or neuropathic pain with comorbid low mood/anxiety; monitor for suicidality warnings and recent recalls in specific lots. FDA Access Data+2FDA Access Data+2
Topical agents (lidocaine patches, diclofenac gel): Local pain relief with less systemic risk; follow label limits on duration/area. (Use FDA-labeled products as directed.) FDA Access Data
Tizanidine (spasticity, selected cases): Occasionally considered if clear spasticity coexists (uncommon in ANO5). Sedation/hypotension possible; reserve for targeted times. FDA Access Data+1
Baclofen (spasticity, selected cases): Similar caveat; taper slowly to avoid withdrawal reactions noted on labels (oral/IT). FDA Access Data+1
Short course muscle relaxants for acute spasms: Very selective use for brief flares; sedation is common; avoid chronic use. (General label safety principles.) FDA Access Data
Proton-pump inhibitor or H2 blocker (if frequent NSAID use): GI protection strategy in high-risk patients—only when risk justifies. (Follow individual FDA labels.) FDA Access Data
Antiemetics during rhabdo-related illness (as indicated): Symptom control to maintain hydration. (Use FDA-labeled ondansetron/prochlorperazine per label.) FDA Access Data
Oral rehydration solutions: For supportive care in minor exertional illness; check sodium/sugar loads and comorbidities. (General OTC label guidance.) FDA Access Data
Sleep aids (cautious, short-term): Prioritize behavioral sleep therapy; if pharmacologic, choose agents with safer profiles and clear stop plans per label. FDA Access Data
Vitamin D (if deficient): Treat per guidelines to support bone/muscle function; dosing per national guidance and product label. LGMD Awareness Foundation
Calcium (if diet is low): Only if indicated; avoid excess. (Label-based dosing.) LGMD Awareness Foundation
Topical analgesic heat/cold gels: Symptom relief adjuncts; check skin tolerance. (OTC label guidance.) FDA Access Data
Stool softener with opioid use (if ever needed): To prevent constipation during short opioid courses after injuries or procedures. (FDA label guidance.) FDA Access Data
Vaccinations (per schedule): Prevent illness-triggered deconditioning/rhabdo; follow vaccine labels/schedules. LGMD Awareness Foundation
Electrolyte replacement (when clinically indicated): Corrects deficits that worsen cramps/fatigue; avoid overcorrection. (FDA-labeled oral solutions.) FDA Access Data
Topical NSAID gel for focal pain: Lower systemic exposure than oral NSAIDs; follow site/amount limits on the label. FDA Access Data
Avoid routine systemic steroids or immunosuppressants in ANO5 LGMD: Misdiagnosis as inflammatory myositis has led to long, unhelpful exposure; genetics should guide. jnnp.bmj.com

Dietary molecular supplements

There is no supplement proven to fix ANO5 defects. Some patients and clinicians use the following for general muscle health; quality evidence is limited and products vary.
Creatine monohydrate, whey protein, omega-3s, vitamin D (if low), magnesium (if low), CoQ10, B-complex (if deficient), curcumin, tart cherry, electrolytes—each may support recovery, reduce DOMS, or correct deficiencies; dosing should follow product labels and professional guidance to avoid interactions (e.g., anticoagulants with omega-3s/curcumin). Family guides for LGMD emphasize nutrition adequacy rather than “megadoses.” LGMD Awareness Foundation

Immunity-booster/regenerative/stem-cell” drugs

Right now, there are no approved immune-boosting, regenerative, or stem-cell drugs proven to treat ANO5-related LGMD. Experimental approaches (gene transfer, cell therapies, membrane-repair targeting) are in research phases; participation is via clinical trials with strict safety oversight. Avoid commercial “stem cell” clinics that are not regulated. Focus on vaccinations, nutrition, sleep, and graded exercise—these are the safe ways to support your body’s defense and repair. PMC

Surgeries

Tendon-lengthening for fixed Achilles contracture: Rare in ANO5; considered only if conservative care fails and gait is severely limited. NCBI
Orthopedic stabilization after recurrent falls/fractures: Standard trauma care as needed. LGMD Awareness Foundation
Foot/ankle procedures for severe deformity: For selected distal-pattern cases to improve brace fit/foot clearance. LGMD Awareness Foundation
Spine surgery (unrelated conditions): Only if clear structural indications; muscle disease alone is not an indication. LGMD Awareness Foundation
Intrathecal baclofen pump (if true spasticity with major impact and conservative therapy fails): Rare in ANO5; has withdrawal risks if abruptly stopped—specialist centers only. FDA Access Data

Preventions

Choose hydration, heat avoidance, gradual training, rest days, illness down-shifts, fall-proofing the home, adequate protein/vitamin D, healthy weight, regular check-ins with rehab and genetics, and a written rhabdomyolysis plan (what to do if dark urine or severe pain appears). These actions reduce flares, injuries, and hospitalizations. enmc.org+1

When to see doctors (red flags)

Dark, cola-colored urine after exertion or heat exposure.
New severe muscle pain and swelling that does not settle with rest.
Rapid loss of walking ability, repeated falls, or new knee hyperextension.
Trouble breathing, chest pain, or fainting (rare in ANO5, but urgent if present).
Medication questions before starting new drugs that can affect muscles.
Each of these needs prompt assessment to prevent kidney injury, fractures, or other complications. enmc.org+1

What to eat” and “what to avoid

Eat more:

Water and oral rehydration around activity.
Lean proteins (fish, eggs, legumes, dairy) spaced through the day.
Whole grains, fruits, vegetables for micronutrients/antioxidants.
Calcium and vitamin D sources (or supplements if prescribed).
Healthy fats (olive oil, nuts, seeds) for balanced calories. LGMD Awareness Foundation

Avoid/limit:

Extreme diets with low protein or very low calories.
Binge exercise after inactivity (risk of rhabdo).
Heavy alcohol (dehydration/myopathy risk).
Unregulated supplements promising “cures.”
High-heat outdoor workouts without cooling/hydration plans. enmc.org+1

FAQs

Is ANO5 LGMD curable? Not yet; research is active. Current care focuses on safe exercise, symptom control, and preventing flares. PMC
Will I need a wheelchair? Many people remain ambulant for years; progression is often slow, and wheelchair use—if needed—tends to be late. LGMD Awareness Foundation
Is my heart at risk? Heart and lung problems are less common than in some other LGMDs, but a baseline screen is still sensible. LGMD Awareness Foundation
Why do my calves look big? Pseudohypertrophy can occur—muscle is replaced by fat/fibrous tissue over time while still appearing bulky. Lippincott Journals
Can I lift weights? Yes, with guidance—use light-to-moderate, concentric-biased routines; avoid high-force eccentric training. nmd-journal.com
How do I prevent rhabdomyolysis? Hydrate, avoid heavy exertion in heat, progress training slowly, and rest when ill; seek care if urine turns dark. enmc.org
Do steroids help? Not for ANO5 LGMD; misdiagnosis as inflammation has led to unnecessary immunosuppression in case series. jnnp.bmj.com
Which pain medicine is safest? It depends on your health profile. Acetaminophen avoids NSAID GI/CV warnings but has its own max-dose limits. Decide with your clinician. FDA Access Data
Are supplements required? Only to correct deficiencies (e.g., vitamin D) or as adjuncts; none repair ANO5. Food-first plus targeted supplements is the usual approach. LGMD Awareness Foundation
Can children get ANO5 disease? Most cases start in adolescence/adulthood, but onset varies. Genetic testing clarifies. NCBI
Is there a specific ANO5 diet? No. Aim for balanced calories and adequate protein; avoid dehydration and crash diets. LGMD Awareness Foundation
Will I pass this to my children? As an autosomal recessive disease, your children are typically carriers unless your partner is also a carrier; genetic counseling helps quantify risk. NCBI
Are there support groups? Patient groups and LGMD family guides offer practical tips and research updates. LGMD Awareness Foundation
What if my doctor suspects inflammation? Request genetics before long immunosuppression; ANO5 often mimics inflammatory myopathy but responds poorly to steroids. jnnp.bmj.com
Where can I read more science? GeneReviews, recent narrative reviews, and basic science on membrane repair in ANO5 are good starting points. NCBI+2PMC+2

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