Congenital muscular dystrophy with intellectual disability

What it is

From: Orphanet

A rare, genetic, congenital muscular dystrophy due to dystroglycanopathy disorder characterized by a wide phenotypic spectrum which includes hypotonia and muscular weakness present at birth or early infancy and delayed or arrested motor development, associated with mild to severe intellectual disability and variable brain abnormalities on neuroimaging studies. Feeding difficulties, joint and spinal deformities, respiratory insufficiency, and ocular anomalies (e.g. strabismus, retinal dystrophy, oculomotor apraxia) may be associated. Decreased or absent alpha-dystroglycan on immunohistochemical muscle staining and elevated serum creatine kinase are observed.

Reported clinical features and what the terms mean

The following findings are associated with this condition in Orphanet. They are not a checklist for diagnosing yourself, and they do not all occur in every affected person. Some are examination, imaging or laboratory findings that cannot be recognised at home.

The frequency labels describe how often a finding was reported among people with the condition in the source. They do not give the chance that a person with that symptom has the condition. Definitions below reproduce HPO terminology; they explain the term, not the likely severity in an individual.

Elevated circulating creatine kinase concentration · Very frequent (99-80%)

The activity of creatine kinase in the blood circulation is above the upper limit of normal.

Floppy infant · Very frequent (99-80%)

Floppiness/hypotonia is defined as reduced resistance to passive movement of joints. Physical examination of floppy/hypotonic infants shows head lag, lack of shoulder and elbow muscle contraction on traction response, inability to tighten the shoulder girdle muscles (or slipping through) when held under the axillae, scarf sign (when the arm is pulled to the opposite side, the arm wraps around the neck with the elbow crossing midline), hyperdorsiflexion of the feet, easy apposition of the thumb against the forearm, feet touching the cheek with ease and without discomfort, frog leg position, and inverted U sign on ventral suspension (head, arms, and legs hanging down without elbow or knee flexion and the trunk rounded in a dome shape).

Hypoglycosylation of alpha-dystroglycan · Very frequent (99-80%)

A reduction in the degree of glycosylation of alpha-dystroglycan in muscle tissue.

Intellectual disability · Very frequent (99-80%)

The term intellectual disability or intellectual developmental disorder is used to describe significantly sub-average intellectual and adaptive functioning based on clinical assessment and as measured by individually administered, appropriately normed, standardized and validated tests of intellectual functioning and adaptive behavior, with onset during the developmental period from infancy through adolescence.

Reduced muscle fiber alpha dystroglycan · Very frequent (99-80%)

Immunohistochemistry reveals reduced alpha dystroglycan protein in the muscle biopsy. Alpha-dystroglycan is a heavily glycosylated peripheral-membrane component of the dystrophin-associated glycoprotein complex (DAPC), which, in addition to laminin alpha2, binds perlecan and agrin in the extracellular matrix, whereas beta-dystroglycan, derived from the same gene, is a transmembrane protein that links to dystrophin intracellularly.

Calf muscle hypertrophy · Frequent (79-30%)

Muscle hypertrophy affecting the calf muscles.

Cerebral cortical atrophy · Frequent (79-30%)

Atrophy of the cortex of the cerebrum.

Fatigable weakness of skeletal muscles · Frequent (79-30%)

A type of weakness of skeletal muscle 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.

Feeding difficulties · Frequent (79-30%)

Impaired ability to eat related to problems gathering food and getting ready to suck, chew, or swallow it.

Global developmental delay · Frequent (79-30%)

A delay in the achievement of motor or mental milestones in the domains of development of a child, including motor skills, speech and language, cognitive skills, and social and emotional skills. This term should only be used to describe children younger than five years of age.

Limb-girdle muscle weakness · Frequent (79-30%)

Weakness of the limb-girdle muscles (also known as the pelvic and shoulder girdles), that is, lack of strength of the muscles around the shoulders and the pelvis.

Microcephaly · Frequent (79-30%)

Head circumference below 2 standard deviations below the mean for age and gender.

Motor delay · Frequent (79-30%)

A type of Developmental delay characterized by a delay in acquiring motor skills.

Poor gross motor coordination · Frequent (79-30%)

An abnormality of the ability (skills) to perform a precise movement of large muscles with the intent to perform a specific act. Gross motor skills are required to mediate movements of the arms, legs, and other large body parts.

Other findings in the same source

From: Orphanet

Additional reported features include Multiple joint contractures (Frequent (79-30%)); Abnormal periventricular white matter morphology (Occasional (29-5%)); Abnormality of connective tissue (Occasional (29-5%)); Abnormality of the eye (Occasional (29-5%)); Abnormality of the nervous system (Occasional (29-5%)); Abnormality of the pons (Occasional (29-5%)); Axial muscle weakness (Occasional (29-5%)); Cerebellar hypoplasia (Occasional (29-5%)); Cerebellar vermis hypoplasia (Occasional (29-5%)); Cryptorchidism (Occasional (29-5%)). This is a selected summary, not a complete description of the condition.

When it may begin

From: Orphanet

Infancy; Neonatal

Inheritance in the source

From: Orphanet

Autosomal recessive

Frequency and the population described

From: Orphanet

Point prevalence: Not yet documented; Worldwide; Class only. Annual incidence: Unknown; Worldwide; Class only.

Understanding the inheritance label

From: MedlinePlus Genetics

An autosomal recessive pattern usually involves disease-causing changes in both copies of a gene. Parents may each carry one altered copy without having the condition themselves. A genetic counsellor can explain carrier testing and reproductive implications using the actual laboratory findings, rather than the condition name alone.

Which doctor should you see?

The suggested department for discussing Congenital muscular dystrophy with intellectual disability is Neurology, with a neurologist as the relevant type of clinician. General physician / Family Medicine; paediatrician for children. Referral depends on symptoms.

Additional services that may be relevant, depending on the findings, include: Clinical Genetics.

This is an editorial referral starting point. The appropriate clinic depends on the person’s age, symptoms, previous diagnosis and local services. The first clinician can decide whether another specialty or a team is needed; a department label does not confirm the diagnosis.

How to prepare for an assessment

Bring a short timeline of the main symptoms: when they first appeared, whether they are constant or episodic, what seems to change them, and how they affect daily activities. Include previous reports, discharge summaries, current medicines and supplements, allergies, and any relevant family history. A dated record is more useful than trying to match every feature in an online article.

Ask the clinician what is already established and what remains uncertain. If a test is suggested, ask what question it answers, what its limitations are and how the result would change the next step. The information here is not an instruction to arrange every possible test. In children, bring growth, developmental and school information if it is relevant to the concern.

• Which nervous-system findings help explain the symptoms?
• Would an assessment of walking, communication or daily function be helpful?
• Are rehabilitation or other specialist services relevant?

Treatment discussions and follow-up

The material gathered for this draft does not provide a complete condition-specific treatment pathway for Congenital muscular dystrophy with intellectual disability. That gap does not mean that treatment is unavailable. A clinician needs to establish the diagnosis and review current guidance before recommending medicines, procedures, rehabilitation or other support.

Before leaving the appointment, clarify the next review date, who will communicate results, and whom to contact if the situation changes. Discuss difficulties with sleep, work, school, mobility, eating or emotional wellbeing when these are relevant. Practical support may require coordination between the treating clinician and other services.

The collected references do not establish a complete prevention or long-term outlook section for this entry. Missing information should not be interpreted as proof that prevention is impossible or that a particular outcome is inevitable. Ask what is known for the exact subtype, stage and personal circumstances, and which uncertainties remain.

When to seek emergency help

Severe breathing difficulty, collapse, new stroke-like symptoms, a seizure that is prolonged or repeated without recovery, uncontrolled major bleeding, or an immediate risk of self-harm require emergency help. In India, call 112 or reach the nearest emergency department. This is a general, non-exhaustive warning list; it is not a condition-specific triage tool.