Central core disease (CCD)

Overview

Central core disease (CCD) is a genetic condition present from birth or early childhood, part of the wider congenital myopathy group. It takes its name from unusual pale 'core' areas visible in muscle fibres when examined under a microscope.

Symptoms

Signs are usually noticed at or shortly after birth, though occasionally mild cases go unrecognised for years. Weakness centres on the hips, upper legs, shoulders and upper arms; early clues include low muscle tone and being a little behind on milestones like sitting and walking. Cramps, stiffness and fatigue are common, and in severe cases some muscle wasting can occur. The heart and breathing muscles are usually spared. Weakness around the hips can lead to hip dislocation or contractures, particularly at the hips and knees, and some people develop foot deformities or scoliosis.

Inheritance and cause

CCD is caused by changes in the RYR1 gene, which provides instructions for a protein central to how muscles contract and relax properly. Most cases are autosomal dominant — a single changed copy is enough — though a recessive form exists, and sometimes the change arises for the first time with no family history. Crucially, RYR1 is also linked to malignant hyperthermia (MH), a potentially life-threatening reaction to certain anaesthetic drugs.

Getting a diagnosis

A GP typically refers on to a paediatrician or neurologist, who carries out a physical assessment and may arrange a muscle MRI, muscle biopsy, or genetic testing. A biopsy showing central cores in type 1 muscle fibres is characteristic; a blood test checking the RYR1 gene can sometimes confirm the diagnosis without needing a biopsy at all.

Management and outlook

Care works best through a multidisciplinary team led by a neurologist. Physiotherapy and moderate exercise — swimming, walking, gentle cycling — help maintain strength, mobility and breathing capacity, though vigorous or excessive exercise should be avoided. Orthopaedic support (splints, braces, sometimes surgery) helps manage contractures and scoliosis.

The single most important thing to flag before any procedure: because of the RYR1 link, anyone with CCD carries a raised risk of malignant hyperthermia under general anaesthesia. Every anaesthetist needs to know the diagnosis in advance — dantrolene is the emergency treatment for an MH reaction, and certain drugs (including suxamethonium) should be avoided altogether.