MTHFR

Methylenetetrahydrofolate reductase or MTHFR: "The MTHFR gene provides instructions for making an enzyme called methylenetetrahydrofolate reductase. This enzyme plays a role in processing amino acids, the building blocks of proteins. Methylenetetrahydrofolate reductase is important for a chemical reaction involving forms of the B-vitamin folate (also called folic acid or vitamin B9). Specifically, this enzyme converts 5,10-methylenetetrahydrofolate to 5-methyltetrahydrofolate. This reaction is required for the multistep process that converts the amino acid homocysteine to another amino acid, methionine. The body uses methionine to make proteins and other important compounds." http://ghr.nlm.nih.gov/gene/MTHFR

The symptoms can vary depending on the mutation: One can be homozygous for C677T or A1298C or heterozygous and even from person to person depending on other biological and genetic issues.
My one son is 11 and exhibits many symptoms that are related to his homozygous C677T and possibly to mitochondrial issues, and a Chromosome 16.13 microdeletion. He has apsergers, bi-lateral hydronephrosis,  autonomic issues, and more.

Some of the common recommendations are:

1. Limit ingestion of folic acid in fortified foods as you cannot process folic acid well.
2. Limit or cease taking supplements or drugs with folic acid in them. Talk with your doctor before stopping.
3. Avoid folic acid blocking drugs such as birth control or Methotrexate.
4. Avoid drugs which increase homocysteine such as Nitrous Oxide (most used in dentistry)
5. Avoid antacids as they block absorption of vitamin B12 and other nutrients
6. Begin understanding which of your symptoms may be related to the C677T MTHFR mutation.
7. Measure homocysteine levels – properly!
8. Inform your family members so they can also test for the MTHFR mutation
9. Find a doctor who is knowledgeable about MTHFR or is willing to learn
10. If you are pregnant, find an OB/GYN or midwife who is knowledgeable about MTHFR.
11. Eliminate Gluten from your diet – especially wheat.
12. Eliminate or reduce Dairy from your diet. If you must have dairy, use Goat milk.
13. Sauna or sweat somehow (epsom salt baths, sports, yoga..) at least once to three times a week.
14. Limit intake of processed foods
15. Increase intake of whole foods and home-prepared meals
16. Eat the Rainbow of colors from fruits and vegetables – daily
17. Castor Oil Packs over your abdomen daily during times of pain, soreness, cramps
18. Vegetable/Fruit Juice Diet with Chia Seeds during times of pain, soreness, cramps
19. Limit intake of high methionine-containing foods if homocysteine elevated
20. Coffee Enemas during times of detoxification or pain
21. Filter chlorine from your drinking water, shower and bath.
22. Drink at least two liters of filtered water daily mixed with vitamin C and electrolytes.
23. Eat smaller, but more frequent meals, throughout the day with some form of protein.
24. Limit protein intake to approximately 0.7 grams protein per kilogram of body weight.
25. Remove mercury amalgams and root canals with a trained biological dentist.
26. Avoid cooking, drinking, storing and heating in any type of plastic container.
27. Use an air purifier in your home and office
28. Eliminate carpets from your home and install low VOC wood or tile flooring.
29. Eat grass-fed beef, free range, hormone free and antibiotic meats and eggs
30. Cook with electric stove and oven and remove gas stove and oven.

General Nutrient Recommendations for C677T MTHFR mutations:

• Methylfolate
• Methylcobalamin
• Betaine in the form of TMG
• NAC
• Glutathione
• Pyridoxal-5-phosphate
• Riboflavin
• Curcumin
• Mixed tocopherals (vitamin E)
• Silymarin (Milk Thistle)
• EPA/DHA
• Phosphatidylcholine
• Nattokinase
• Vitamin C
• Vitamin D3
• Comprehensive multivitamin/multimineral
• Probiotics

http://mthfr.net/mthfr-c677t-mutation-basic-protocol/2012/

My other children and I have different mutations which require similar yet different precautions and nutritional suggestions.