check with their doctor or genetic counselor. predictive testing it is possible to test someone who is at risk for developing dm1 before they are showing symptoms to see whether they inherited an expanded trinucleotide repeat. this is called predictive testing. predictive testing cannot determine the age of onset that someone will begin to have symptoms or the course of the disease. if the child is not having symptoms, the testing is not possible with an exception of emancipated minors as a policy. auxiliary testing electrodiagnostic testing (emg and ncs) can detect the electrical signs of myotonia before myotonia becomes noticeable to the affected individual. muscle biopsy can reveal damage of the muscle, but findings are generally nonspecific and do not greatly aid in diagnosis. management there is currently no cure for or treatment specific to myotonic dystrophy. management is focused on the complications of the disease, particularly those related to the lungs and heart, which are life-threatening. complications relating to the cardiopulmonary system account for 70% of deaths due to dm1. compromised lung function can, in turn, contribute to life-threatening complications during anesthesia and pregnancy. lung complications are the leading cause of death in dm1, warranting lung function monitoring with pulmonary function tests every 6 months. central sleep apnea or obstructive sleep apnea may cause excessive daytime sleepiness, and these individuals should undergo a sleep study. non-invasive ventilation may be offered if there is an abnormality. otherwise, there is evidence for the use of modafinil as a central nervous system stimulant, although a cochrane review has described the evidence thus far as inconclusive. cardiac complications are the second leading cause of death in dm1, and commonly no symptoms are present prior to adverse events. all affected individuals are advised to have an annual or biennial ecg. pacemaker insertion may be required for individuals with cardiac conduction abnormalities. improving the quality of life which can be measured using specific questionnaires is also a main objective of the medical care. physical activity there is a lack of high-quality evidence to determine the effectiveness and the safety of physical activities for people who have myotonic dystrophy. further research is required to determine if combined strength and aerobic training at moderate intensity is safe for people who have neuromuscular diseases, however the combination of aerobic and strength exercises may increase muscle strength. aerobic exercise via stationary bicycle with an ergometer may be safe and effective in improving fitness in people with dm1. cardiovascular impairments and myotonic sensitivities to exercise and temperature necessitate close monitoring of people and educating people in self-monitoring during exercise via the borg scale, heart rate monitors, and other physical exertion measurements. orthotics muscular weakness of dorsiflexors (dorsiflexion) hinders the ability to clear the floor during the swing phase of gait and people may adopt a steppage gait pattern or ankle-foot-orthotics may be indicated. factors such as hand function, skin integrity, and comfort must be assessed prior to prescription. neck braces can also be prescribed for neck muscle weakness. mobility aids and adaptive equipment upper and lower limb weakness, visual impairments and myotonia may lead to the need for mobility aids and functional adaptive equipment such as buttonhooks and handled sponges for optimal hand function. if assistive devices and home adaptations are needed, physical therapists may refer on to occupational therapist(s) for further assessment. prognosis life expectancy in non-congenital late-onset or adult onset dm1 is in the early 50s, with pulmonary complications being the leading cause of death, followed by cardiac complications. dm2 life expectancy has yet to be studied. epidemiology the prevalence of dm1 ranges from 5 to 20 per 100,000 (1:20,000–1:5000). up to 48 per 100,000 (1:2100) of individuals tested positive for the mutation of dm1 in new york, although not all of these individuals would have become symptomatic. again in new york, premutations for dm1 were found in 191 per 100,000 (1:525). dm2 prevalence is not known, but genetic studies estimate it to be as high as 1:1830. dm affects males and females approximately equally. about 30,000 people in the united states are affected. in most populations, dm1 appears to be more common than dm2. however, recent studies suggest that type 2 may be as common as type 1 among people in germany and finland. dm1 is the most common form of myotonic muscular dystrophy diagnosed in children, with a prevalence ranging from 1 per 100,000 in japan to 3–15 per 100,000 in europe. the prevalence may be as high as 1 in 500 in regions such as quebec, possibly due to the founder effect. the incidence of congenital myotonic dystrophy is thought to be about 1:20,000. history myotonic dystrophy was first described by a german physician, hans gustav wilhelm steinert, who first published a series of 6 cases of the condition in 1909. isolated case reports of myotonia had been published previously, including reports by frederick eustace batten and hans curschmann, and type 1 myotonic dystrophy is therefore sometimes known as curschmann-batten-steinert syndrome. the underlying cause of type 1 myotonic dystrophy was determined in 1992. research directions altered splicing of the muscle-specific chloride channel 1 (clc-1) has been shown to cause the myotonic phenotype of dm1 and is reversible in mouse models using morpholino antisense to modify splicing of clc-1 mrna. some small studies have suggested that imipramine, clomipramine and taurine may be useful in the treatment of myotonia. however, due to the weak evidence and potential side effects such as cardiac arrhythmias, these treatments are rarely used. a recent study in december 2015 showed that a common fda approved antibiotic, erythromycin reduced myotonia in mice. human studies are planned for erythromycin. erythromycin has been used successfully in patients with gastric issues.