Do you mean like blood test (genetic test) and needle in his muscle in his shin to listen to the noise the muscle makes? Both my husband and I are carriers and both passed our myotonia gene :(
Caleb has symptoms not sure if they are classed as strong. When he gets out of the car we have to hold his hand otherwise he falls over, massive calves, biceps, 6 pack on empty tummy, stiff, unstable running and walking. We were kept being told he was just delayed with his development but we knew there was more too it so finally got answers.
Started magnesium oil spray recently so hopefully that gives him some relief.