MedGen

Down syndrome, the most frequent form of mental retardation caused by a microscopically demonstrable chromosomal aberration, is characterized by well-defined and distinctive phenotypic features and natural history. It is caused by triplicate state (trisomy) of all or a critical portion of chromosome 21. [from OMIM]

The Headache Classification Committee of the International Headache Society (1988) classified headache associated with sexual activity (HSA) as an idiopathic headache under 'miscellaneous headaches unassociated with structural lesions.' Based on initial descriptions, 3 subtypes are differentiated: type 1 is a dull ache in the head and neck that slowly intensifies as sexual excitement increases, and is believed to be caused by muscle contraction similar to tension-type headache; type 2, also called 'vascular-type,' is a sudden severe, explosive headache occurring at orgasm, which may be due to increased intracranial pressure; type 3, the most uncommon type, is a postural headache resembling that caused by decreased CSF pressure, perhaps due to a meningeal tear during coitus (summary by Frese et al., 2003). [from OMIM]

A type of cardiac arrhythmia with premature atrial contractions or beats caused by signals originating from ectopic atrial sites. [from HPO]

An infection that is caused by Gonococcus. [from NCI]