Late-onset Steinert myotonic dystrophy is a rare form of muscular dystrophy that typically affects adults over the age of 40. It is characterized by progressive muscle weakness and wasting, as well as myotonia (involuntary muscle contractions). Other symptoms may include difficulty speaking, swallowing, and breathing, as well as vision and hearing problems.

The symptoms of Late-onset Steinert myotonic dystrophy can vary from person to person, but generally include:

- Muscle Weakness and wasting, especially in the face, neck, and hands
- Difficulty with fine motor skills, such as buttoning a shirt or writing
- Drooping eyelids
- Difficulty swallowing
- Speech problems
- Cognitive impairment
- Heart problems
- Diabetes
- Cataracts
- Sleep disturbances
- Heat intolerance
- Abnormal sweating

Late-onset Steinert myotonic dystrophy is caused by a genetic mutation in the DMPK gene. This gene mutation causes an abnormal buildup of a protein called myotonin protein kinase (MTPK) in the body. This buildup of MTPK leads to the symptoms of the disorder.

1. Medications: Medications such as mexiletine, quinine, and phenytoin can be used to reduce muscle stiffness and spasms.

2. Physical Therapy: Physical therapy can help improve muscle strength, flexibility, and coordination.

3. Assistive Devices: Assistive devices such as wheelchairs, walkers, and canes can help improve mobility.

4. Surgery: Surgery may be recommended to correct any deformities or contractures caused by the disease.

5. Speech Therapy: Speech therapy can help improve communication skills.

6. Occupational Therapy: Occupational therapy can help improve daily living skills.

7. Nutritional Support: Nutritional support can help maintain muscle strength and health.

8. Genetic Counseling: Genetic counseling can help individuals and families understand the risks

1. Age: Late-onset Steinert myotonic dystrophy typically affects people over the age of 40.

2. Gender: Men are more likely to be affected than women.

3. Family history: Having a family member with the condition increases the risk of developing it.

4. Ethnicity: People of European descent are more likely to be affected than other ethnicities.

5. Genetic mutation: A mutation in the DMPK gene is the cause of the condition.

At this time, there is no cure for late-onset Steinert myotonic dystrophy. However, there are medications that can help manage the symptoms of the condition. These include medications to help with muscle spasms, pain, and fatigue, as well as medications to help with sleep disturbances. Additionally, physical and occupational therapy can help improve muscle strength and coordination.