Czeizel-Losonci syndrome (CLS) is an extremely rare congenital disorder noted for its severe malformations. It is characterized by limb abnormalities such as split hand or split foot, as well as problems with the spine like spina bifida. In addition, people with this condition may experience hydronephrosis, which affects the kidneys, and other skeletal manifestations including thoracolumbar scoliosis and radial defects. Spinal issues in this syndrome can include different forms of spina bifida, and there may also be a diaphragmatic defect known as Bochdalek hernia. This disorder has been described in the literature only up until 1987, and information beyond these reports is limited.

People with Czeizel-Losonci syndrome may show a range of symptoms including split hand or split foot, hydronephrosis (swelling of the kidney due to urine buildup), spina bifida, and other skeletal issues like thoracolumbar scoliosis and radial defects. Diaphragmatic defects such as Bochdalek hernia have also been reported as part of the condition.

Czeizel-Losonci syndrome is described as a congenital genetic malformation disorder, meaning that the changes are present at birth. However, beyond this categorization, the exact genetic factors or causes remain unclear.