essentialmedgen.com

Mutations and single nucleotide polymorphisms (SNPs)

Based at the Institute of Medical Genetics in Cardiff, Wales.
Database of genomic variants and related clinical information
CanVar UK

Cancer predisposition gene variant database.

 InSiGHT

International Society for Gastrointestinal Hereditary Tumours

Leiden Open Variation Database.

Human Genome Variation Society

Provides guidelines for the correct naming of mutations.

Genome aggregation database. Huge database of variants detected by exome and genome sequencing.
 dbSNP

NCBI single nucleotide polymorphism (SNP) database

Franklin variant interpretation website.
Contains large quantities of SNP-related data for each gene. Type in the gene name; scroll down until the SNP section; then can select "see all" and read the SNP genomic position, type, etc

For more details regarding these databases and a user's guide on how to make the most efficient use of these databases, see Part 3 of Essential Medical Genetics 6th Edition