PROJECT SUMMARY Recent efforts in rare and undiagnosed disorders have made a major impact on the diagnosis of affected families and contributed significantly to scientific knowledge. One of the key goals of the UDN was to recruit, evaluate, and follow up with participants from minorities and underserved populations. Despite efforts to increase minority participation in research studies, biases are still prevalent, particularly with respect to African American and Hispanic populations. These underserved populations are at risk to benefit less from recent advances compared to non-Hispanic Whites. The vision of the UDN Miami Clinical Site funded during the second phase of UDN has been to enhance the inclusion of minority populations in UDN studies. South Florida is one of the most diverse metro areas in the US, with 70% Hispanics, which truly represent all regions of the Caribbean and Central and South America. At the Miami Clinical Site, we have enrolled over 60 participants, as planned during the second phase of UDN; the majority of our participants are from minorities and from underrepresented populations. Thus far we reached a diagnosis in one-third of participants whose evaluations are completed. In addition, we have identified several candidate genes, which are functionally characterized. Further, we analyzed UDN-wide data for repeat expansions and identified causative variants explaining the observed phenotype. In this proposal, we will continue to enroll and evaluate at least 15 participants from our highly diverse catchment area as part of UDN. We will establish collaboration with the new Data Management and Coordinating Center, and transition to the third phase of UDN as a sustainable diagnostic center of excellence.