It's not all that uncommon; I know several people with it, including me, and we all lead normal, healthy lives. It's caused, as I understand it, by a liver enzyme abnormality. The symptoms it causes are very occasional bouts of lethargy, possible headache, and slightly jaundiced appearance, usually triggered by 'stressing' the liver by, for instance, overindulgence in alcohol or fasting. Colds shouldn't be connected with Gilberts.Only your cousin knows if she's exaggerating her symptoms for attention!