Genetic Relationship and Fingerprinting (GRAF)
Genetic Relationship and Fingerprinting (GRAF) is a rapid statistical method to detect duplicates and closely related samples in large genomic datasets to be used as a quality assurance tool in dbGaP data processing.  For more information, see this abstract in PubMed. 
https://www.ncbi.nlm.nih.gov/pubmed/28609482