25% of hypertensive crises have been found to be hypertensive emergency versus urgency when presenting to the ER.Risk factors for hypertensive emergency include age, obesity, noncompliance to anti hypertensive medications, female sex, Caucasian race, preexisting diabetes or coronary artery disease, mental illness, and sedentary lifestyle. Several studies have concluded that African Americans have a greater incidence of hypertension and a greater morbidity and mortality from hypertensive disease than non-Hispanic whites, however hypertensive crises have a greater incidence in Caucasians. Although severe hypertension is more common in the elderly, it may occur in children (though very rarely), likely due to metabolic or hormonal dysfunction. In 2014, a systematic review identified women as having slightly higher increased risks of developing hypertensive crises than do men.With the usage of anti hypertensives, the rates of hypertensive emergencies has declined from 7% to 1% of patients with hypertensive urgency.16% of patients presenting with hypertensive emergency can have no known history of hypertension. See also
Hypertensive retinopathy
Hypertensive encephalopathy
Preeclampsia
Eclampsia
Aortic dissection
Intracranial hemorrhage

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Weakening of the hair associated with pili torti also causes alopecia in approximately 80% of patients.The severity of hearing loss associated with Björnstad syndrome varies. Some individuals are unable to hear sounds at certain frequencies, while others are completely deaf. Their hearing loss is caused by tissue damage of the inner ear. Genetics
Björnstad syndrome is caused by a mutation in the BCS1L gene (position 2pq35) and is inherited in an autosomal recessive pattern. BCS1L is a protein that adds Rieske Fe/S to complex III during oxidative phosphorylation of cellular respiration. Mutations of BCS1L gene prevents the protein product from aiding in complex III formation, which reduces oxidative phosphorylation and increases the production of reactive oxygen species.Two missense mutations linked to Björnstad syndrome have been documented, but several other variants are suspected to be pathogenic. The clinical severity of different BCS1L mutations may be caused by the varying production of reactive oxygen species. The symptoms of Björnstad syndrome may be attributed to a particular sensitivity of inner ear and hair tissues to reactive oxygen species, but more research is needed. Mutations of the BCS1L gene may also result in GRACILE syndrome, which is an inherited lethal metabolic disease. Diagnosis
Roar Theodor Björnstad first noticed a correlation between pilli torti and hearing loss in 1965, and subsequently diagnosed eight patients with Björnstad syndrome. Out of these eight patients with pili torti, five experienced sensorineural deafness.