Familial hCG Syndrome is a dominant genetic defect discovered by the USA hCG Reference Service.
If a person has familial hCG syndrome, then one parent has to have it also, in addition to possible kin and children having this syndrome. Familial hCG syndrome is marked by a person producing up to 216 mIU/ml total hCG (USA hCG Reference Service experience with 16 families). As discovered, people seeming produce a combination of mostly hCG free ß-subunit and a mutant hCG variant. Commonly the mutant hCG is not detected by an hCG assay using a ß-subunit C-terminal peptide antibody (9 of 10 automated assays use this kind of antibody that does not detect this mutant hCG, the exception is the Siemens Immulite assays).
The USA hCG Reference Service has experience with 16 families carrying Familial hCG Syndrome. Looking at medical records, hCG production is their only symptom, no other ailment appears to be associated with this syndrome. In 16 of 16 cases similar levels of hCG were found in the patient, and in one parent of the patient. Genetics (performed on one case only) suggests that this is a mutant hCG molecule. The biggest question with this genetic syndrome is what cells in the human body are making the hCG variant?