One of these tests is a blood test, which measures the level of a muscle enzyme called creatine kinase (CK). This enzyme is usually found in the muscles, but, following muscle damage, can leak into the bloodstream; in those with MDC1A, levels of CK in the blood are typically elevated (often to more than 10 times the normal values).
All children with MDC1A have a particular constitution of the white matter of the brain which shows, by six months of age, as altered ’white matter signal’ on brain imaging. Brain MRI (in which clinicians take photos of the brain in a non-invasive way) may be very helpful in identifying the condition in a child, when muscle biopsy appearances are not typical or when a muscle biopsy is not available.
A skin biopsy may also be taken to make a diagnosis of MDC1A, since merosin is absent in both muscle and skin in MDC1A. A skin biopsy involves taking a very small skin sample under a local anaesthetic. However, in most instances a muscle biopsy is preferred since it allows the study of many more proteins and enables the diagnosis of MDC1A even in those in whom merosin expression appears normal.
Genetic tests looking for abnormalities in LAMA2, the gene responsible for MDC1A are now available in UK. These are done in a laboratory in a specific nationally designated centre and can provide a definitive diagnosis. If you would like to have these genetic tests, speak to your neurologist consultant about the nearest place to you and ask them to arrange a referral.