My friend's wife is about 4 - 5 months pregnant. She recently had a blood test that looks for genetic abnormalities (a quad marker I believe). She was called in today and told by a nurse (still waiting to see a doctor) that she tested positive for TCHG, a birth defect that causes death although the test could have been a "positive negative" requiring further tests. I understand that this test is not conclusive but does anyone have any idea what TCHG is? I can't find anything on the net about it.