The NIGMS Human Genetic Cell Repository contains over 6,000 samples associated with nearly 500 OMIM classifications. The phenotype of many of these cell lines specifically affects one or more organelles or cell components. In the Cell Diagram these cell lines are organized according to the cellular location of the affected protein, RNA or metabolic process. These include cellular regions (extracellular space, extracellular matrix and basement membrane, plasma membranes, cytoskeleton and cytosol) and organelles (nucleus, mitochondria, lysosomes, endoplasmic reticulum, Golgi complex, plasma membrane, and peroxisomes). Cell lines with OMIM classifications that are restricted to single cell types (e.g., sickle cell anemia), cell lines with OMIM classifications with no known cellular phenotype (e.g., manic depression), or cellular localization of affected gene product was unknown and chromosomal abnormalities (e.g., Downs syndrome) are not included. In the Cell Diagram over 275 OMIM classifications are represented. In some disorders the effects may occur in multiple components of the cell, however, here we have only represented the most frequently mentioned one(s). The assignments of gene products to cell components was based on information in OMIM, the BRENDA database, Lehninger Principles of Biochemistry 3rd Edition (Worth Publishers, 2000), Molecular Cell Biology 4.0 (Freeman Press, 2000) and references therein. The cell drawing is a composite adapted from all of these sources.