Klippel–Feil syndrome (KFS), also known as cervical vertebral fusion syndrome, is a rare congenital condition characterized by the abnormal fusion of any two of the seven bones in the neck (cervical vertebrae). It results in a limited ability to move the neck and shortness of the neck, resulting in the appearance of a low hairline.The syndrome is difficult to diagnose, as it occurs in a group of patients affected with many different abnormalities who can only be unified by the presence of fused or segmental cervical vertebrae. [Source: Wikipedia ]