Constitutional ring chromosomes causing developmental disorders and somatic ring chromosomes in the form of double minutes, ring and marker chromosomes in various types of tumors have been documented. However, there are no organized efforts to compile and curate cytogenomic and clinical findings from ring chromosome cases. We have developed a web-based interactive Human Ring Chromosome Registry (HRCR) using a Microsoft Access based relational database to present cytogenomic and clinical findings from ring chromosome cases (http://web.gxmu.edu.cn/shengwu/HRC/home.asp). To validate the functional modules in this registry, constitutional ring chromosome cases reported in Chinese patients were compiled as a testing data set. From a total of 113 cases, relative frequencies, cytogenomic findings, and clinical features were summarized. An initial effort, focused on constitutional ring chromosome 21, classified the patients into three groups based on the cytogenomic findings and provided specific recommendations for prenatal and postnatal genetic counseling of ring chromosome 21. Furthermore, cytogenomic and genomic sequencing results from supernumerary ring chromosomes and derived giant marker chromosomes identified in liposarcoma were summarized to reveal the gene content of genomic imbalances, underlying mechanisms of ring formation, and implications for tumor classification and treatment. The development of HRCR has provided an interactive platform to compile and curate cytogenomic and clinical findings for constitutional and somatic ring chromosome cases. We propose a collaborative effort of clinical cytogeneticists and molecular geneticists to contribute to this online ring chromosome resource for establishing genotype-phenotype correlation and developing diagnostic guidelines and recommendations for genetic counseling and precise treatment.