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• DESCRIPTION (provided by applicant): Sleep disordered breathing (SDB) is synonymous with obstructive sleep apnea syndrome and is known to result in daytime sleepiness, fatigue and associated behavioral changes which lead to impaired work performance, increased healthcare burden and thus, presents a significant socio-economic burden to society. Recent studies suggest that >25% of middle-aged population men are afflicted with SDB and this may be an underestimation of the prevalence of SDB in some populations. SDB is strongly correlated with obesity, thus the actual prevalence will likely grow in association with the current obesity epidemic. Moreover, the prevalence of hypertension in patients with SDB is very high (>50%), and the incidence of most cardiovascular disease states is elevated in SDB. Nevertheless, the relation of SDB to the presentation of metabolic syndrome (which includes both obesity and hypertension) remains ill-defined and prospective evaluation of these relationships to metabolic syndrome remains scarce. In addition, despite the growing appreciation of SDB as a significant health risk, there is very little knowledge of the prevalence of SDB (with or without metabolic syndrome) among underrepresented minorities (URM) in which there are often many barriers to proper health care. Thus, specific aim one will prospectively seek to determine the existence and magnitude of the health disparity for SDB within URM populations in patients with and without metabolic syndrome.We have shown in laboratory studies that there is a transient increase in sympathetic nerve activity and blood pressure in response to apnea, with these responses being exaggerated in SDB patients. However, it is unknown whether these differences are present in patients with hypertension or metabolic syndrome. Therefore, specific aim two will address the utility of this physiologic test to distinguish patients with SDB and metabolic syndrome and the presence of a health disparity for these physiologic abnormalities. Many health disparities are likely linked to genetic differences among populations. Recent preliminary findings have identified a potentially important gene (ATP1A2) that is linked to type-2 diabetes and potentially hypertension. Specific aim three will assess the prevalence of this gene in URM and Caucasian populations as an initial step toward development of genetic profiles that present a risk for metabolic syndromes. Therefore, the proposed studies will address the following specific aims. The specific hypotheses are stated for each specific aim and study in the methods section. Specific Aim 1: To determine the discrepancy of prevalence of diagnosis of SDB in URM populations versus the Caucasian population; (Aim 1B) to determine the prevalence of SDB in URM and Caucasian patients with metabolic syndrome; (Aim 1C) to determine the disparity of community awareness of SDB as a contributing barrier to this disparity of prevalence to diagnosis. Specific Aim 2: To determine the predictive reliability of the voluntary apnea pressor response for distinguishing SDB and hypertension in URM and Caucasian patients with and without metabolic syndrome. Specific Aim 3: To determine a) the frequency of the 5' and 3' polymorphisms of the ATP1A2 gene in URM and Caucasian subjects, b) the effect of the 5' mutant alleles on DNA-nucleoprotein interaction, and c) the relation of the presence of the polymorphism to abnormal blood pressure control.