Many families first notice something around infancy or early childhood, such as feeding difficulties, weak muscle tone, or delays in sitting, crawling, or walking; doctors may also pick up unusual facial features or hand/foot differences during routine checkups. Sometimes the first signs of 2q31.1 microdeletion syndrome appear before birth on an ultrasound, which can show limb differences or growth concerns, prompting genetic testing. Later, concerns about speech, learning, or behavior often lead to evaluations that confirm the diagnosis.