The GIAB reference material (NA12878) is useful for validating diagnostic genetic tests but has some limitations. It provided many single nucleotide variants for analysis but few examples of more complex and clinically relevant variants like large indels, copy number variants, and variants in difficult regions. While it demonstrated high accuracy for common variants, it did not adequately represent the full spectrum of variant types seen in clinical cases. More data is needed from a wider diversity of samples with more engineered variants to fully validate tests for their ability to detect pathogenic variants.