The signs and symptoms of 12q14 microdeletion syndrome can be different from person to person depending on the size of the missing piece of chromosome and the genes involved. In general, people with this syndrome have growth delay that starts before they are born, short stature, and poor weight gain. They may have feeding difficulties, speech and developmental delay, and mild intellectual disability. Some people with this syndrome have a triangular shaped face and a large forehead. Many have small areas of increased bone density that show up as bright spots on x-rays, a condition called osteopoikilosis. Osteopoikilosis does not cause pain or other symptoms.

It has been suggested 12q14 microdeletions that include the HMGA2 gene cause some cases of Russell-Silver syndrome, because people with Russell-Silver syndrome and people with 12q14 microdeletion syndromes have similar signs and symptoms.