Organizes information related to human medical genetics, such as attributes of conditions with a genetic contribution. (from website).
The MedGen website can be reached at http://www.ncbi.nlm.nih.gov/medgen/.
The example shown will find medical information about problems in the LCT gene.
NCBI provides an MedGen tutorial at http://www.ncbi.nlm.nih.gov/books/NBK159970/
Start by searching for LCT in MedGen:

The page returned shows various types of medical data:

By selecting the first entry, we see various literature about the clinical findings for LCT mutations:

The 2nd entry returns more detailed information about the gene, including the mode of inheritance, gene location, description of mutation, and other clinical information:

Looking further down the page, we see literature on therapy and diagnosis:
