My son was born with asymmetric crying facies (some doctors called it cullp) – he is 3 years old now and it is still visible. Can anything be done?

Probably not. There are various expressions of this condition: simple missing muscle in that part of face to a complex abnormality of chromosome 22 with far reaching problems, including heart, blood, eye and brain defects. If all your child has is an asymmetric cry, count yourself blessed. Be sure there has been a thorough workup looking for above.