Nutritional and Metabolic Diseases

The National Center for Biotechnology Information (NCBI) of the U.S. National Library of Medicine, National Institutes of Health lists numerous nutritional and metabolic diseases in its collection of articles entitled Genes and Disease.

Of interest is the Gaucher disease which consists of an inherited illness caused by a mutation of a gene responsible for an enzyme that breaks down a particular kind of fat. The good news is that enzyme replacement therapy for this disorder became available in 1991, so there's hope for the possibility of future enzyme replacement therapy for other disorders.

In 1991, enzyme replacement therapy became available as the first effective
treatment for Gaucher disease. The treatment consists of a modified form of the
glucocerebrosidase enzyme given intravenously. Performed on an outpatient basis,
the treatment takes about 1–2 h and is given every 2 weeks. Enzyme replacement
therapy can stop and often reverse the symptoms of Gaucher disease, allowing
patients to enjoy a better quality of life.

full article:
http://www.ncbi.nlm.nih.gov/books/bv.fcgi?rid=gnd.section.227&ref=sidebar