Complete Blood Count (CBC): What You Need to Know About This Common Blood Test

A complete blood count, or CBC, is a common blood test that measures the different cells in your blood, including red blood cells, white blood cells, and platelets. It gives your healthcare provider a broad picture of your overall health and helps detect a wide range of conditions, such as infections, anemia, and certain blood disorders.

The 16p11.2 deletion/duplication test is a genetic test that looks for missing (deletion) or extra (duplication) genetic material in a specific region of chromosome 16, known as p11.2. This test uses molecular genetics methods to analyze your DNA from a blood sample. The 16p11.2 region contains several genes that are important for brain development and function.

Your healthcare provider may order this test as part of a routine health checkup, or to help evaluate symptoms like fatigue, weakness, fever, easy bruising, or unexplained bleeding. It can also be used to monitor an ongoing medical condition or to check how treatments such as chemotherapy or certain medications are affecting your blood cells over time.

Your doctor may recommend this test if you or your child shows signs of neurodevelopmental disorders, particularly autism spectrum disorder (ASD), intellectual disability, developmental delay, speech problems, or behavioral issues. This test is also useful when there is a family history of genetic conditions or when other genetic tests have not provided a clear diagnosis.

Results show whether your blood cell counts fall within normal ranges. A low red blood cell count may suggest anemia, while a high white blood cell count can point to infection or inflammation. Abnormal platelet levels may affect how your blood clots. Your provider will interpret your values together with your symptoms and medical history, so be sure to discuss what your specific results mean for you.

A deletion in the 16p11.2 region means a piece of genetic material is missing, while a duplication means there is extra genetic material. Both can affect how the brain develops and functions. Not everyone with a 16p11.2 deletion or duplication will have symptoms—the effects can vary widely even among family members. Your healthcare provider will interpret your results in the context of your symptoms and family history.

The test is performed by drawing a small sample of blood, usually from a vein in your arm. A healthcare professional cleans the site, wraps a band around your upper arm, and inserts a thin needle to collect the blood into a tube. The procedure takes only a few minutes and may cause a brief pinch. A small bandage is applied afterward, and the sample is sent to a laboratory for analysis.

A healthcare professional will draw a blood sample from a vein in your arm. The sample is then sent to a laboratory where technicians extract DNA and analyze the 16p11.2 region using specialized molecular genetic techniques such as chromosomal microarray analysis (CMA) or quantitative PCR. The test typically takes several weeks for results.