• INCLUSION CRITERIA:

Study population:

Patients must be members of families with familial TGCT as defined below.

Definition of familial TGCT:

The criterion establishing familial TGCT is the presence of:

-at least two cases of documented GCT in blood relatives (at least one of which is testicular in origin),

OR

• a single family member with bilateral testicular cancer,
• men with a history of TGCT who are one in a set of identical siblings will also be included in the study.

Case definition:

A case will be determined to have TGCT according to the following criteria:

• Pathologic confirmation of a germ cell-derived tumor arising in the testis. Extragonadal germ cell tumors will also be included.
• Germ cell-derived histologies including: seminoma, germinoma, embryonal carcinoma, endodermal sinus (yolk sac) tumor, gonadoblastoma, choriocarcinoma, teratoma, and mixed germ cell tumor.
• A case will be determined to have TIN on the basis of pathologic confirmation of intratubular malignant germ cells (ITMGCs) as defined by Burke and Mostofi.

Individuals from participating families who are eligible for this study include:

i) all TGCT cases;

ii) All GCT cases (including those of ovarian or extra-gonadal sites);

iii) all first-degree relatives of each TGCT case;

iv) the spouse(s) of every case if the spouse and case had children who are participating in the study;

v) any blood relative not included in (ii - iii) above who genetically links two cases; and

vi) any blood relative with cancer other than TGCT

vii) family members as described in i) - v) above must be age 12 or greater in order to participate

EXCLUSION CRITERIA:

Families will be deemed ineligible for participation in this study if:

There are not at least two proven cases of GCT in the family, one of which is testicular in origin, unless there is a family member with bilateral testicular cancer;

Deceased TGCT cases lacking both archival sources of tissue for DNA extraction AND lacking surviving spouses and children who are willing to paricipate in the study (unavailability of such persons prohibits inferring the genotype of the deceased individual with TGCT).

Critical informative family members are unwilling to participate (i.e., unwilling to provide written informed consent);