Familial gastric cancer accounts for 10% of all cases, but predisposing genetic variations is unknown except for CDH1 mutation.

Because Germline mutation is believed to be a key aspect of cancer predisposition, we plan to recruit persons with 2 or more affected family members in three-generation pedigree. The investigators will perform a whole-exome sequencing using DNA from blood samples of families including gastric cancer patients and non-gastric cancer patients

1> Patient selection

Enroll criteria:

1) Gastric cancer patients and their first-degree relatives and 2) family with two or more gastric cancer patients within three-generation pedigree.

A three-generation pedigree will be used for diagnostic consideration or risk assessment of rare variation.

Personal history will be acquired by questionnaire which asks smoking, alcohol intake, dietary preference, socioeconomic information and history of previous eradication of HP. For any family member with gastric cancer, age at diagnosis, histology type, methods of treatment or pathological reports will be evaluated.

2> Whole exome sequencing, variant annotation, filtering and prioritization After whole exome sequencing, functional annotation of genetic variants will be conducted using ANNOVAR.

3> Linkage analyses To perform variant and gene-based linkage analysis in pedigrees, data will be analyzed using pedigree-VAAST.

4> Validation using a genechip

Inclusion Criteria :

• Gastric cancer patients and their first-degree relatives
• Members in family with two or more gastric cancer patients within three- generation pedigree

Exclusion Criteria :

• Those who reject the enrollment

The investigator will recruit or invite the participants among persons who visit the clinic with a family history of gastric cancer.

The investigator plans to recruit gastric cancer patients and non-patients in family with 2 or more affected members.

Non-gastric cancer patients was restricted to persons over 50 years of age.