Bethlem myopathy (BM) is a little known muscle disorder, which is named after the Dutch doctor who first described the condition in 1976. Diagnosis and recognition of it has improved over the past few years following work done by a number of researchers around the world on the identification of the protein involved. The protein is called collagen VI. A fault in any of the three genes for collagen VI can give rise to BM.

First symptoms of BM can present at any time from birth through to adulthood and are very variable. In childhood these symptoms can be hypotonia (floppiness), muscle weakness, delayed motor milestones (for example when a baby first sits up unaided or learns to walk), talipes (clubfoot), torticollis (stiff neck) and contractures (tightness) in the ankles, hip, knees and elbows. The contractures are often quite variable and can come and go over time.

Adults with BM can have tight tendons at the back of their ankles, as well as tightness of various other joints (elbows, knees, joints in the back) and especially some of the muscles in the hands. Other symptoms such as poor stamina/poor exercise tolerance and difficulties walking upstairs or doing tasks which require lifting the arms above the head are related to the subtle muscle weakness that tends to go with Bethlem myopathy. In addition, the skin of some people with BM can be unusual. Over the outer surfaces of the arms and legs especially it can feel rough or dry to touch and has been described as looking like “plucked chicken skin”. Other patients might find that they scar in an unusual way, either by forming keloids (raised, rather angry looking scars) or thin silvery “cigarette paper scars”.

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