Cytogenetics is the study of chromosome structure, pathology, function, and behavior as it relates to genetic disease. Cytogenetic analysis uses routine G-banded chromosome analysis and higher-resolution banding as well as molecular methods such as fluorescence in situ hybridization (FISH) and whole genome microarray analysis. Chromosome abnormalities identified using these tests can give physicians and patients clues to the etiology of diseases and conditions, including multiple congenital anomalies, developmental delay, autism, and pregnancy loss. Our Constitutional Cytogenetic Laboratory offers testing for the identification of chromosomal aberrations in many sample types, including peripheral blood, amniotic fluid, chorionic villus sampling, products of conception, and skin biopsy. The laboratory also offers FISH analysis for certain formalin-fixed, paraffin-embedded solid tumors, including HER2 in breast carcinoma.