Microphthalmia with linear skin defects syndrome (MLS syndrome) is a genetic condition that affects the eyes and skin. It is mainly found in females and is characterized by small or poorly developed eyes (microphthalmia) and characteristic linear skin markings on the head and neck. The signs and symptoms of this condition may include abnormalities of the brain, heart, and genitourinary system. Other symptoms may include short stature, developmental delay, and finger and toenails that do not grow normally (nail dystrophy). MLS syndrome is typically caused by either a deletion of certain genetic material on the p (short) arm of the X chromosome or by a genetic change in the HCCS gene. In some cases, it may be caused by genetic changes in the COX7B and NDUFB11 genes, (also located on the X chromosome). This condition is inherited in an X-linked manner and is thought to result in serious early developmental concerns in males, leading to almost no males with this condition surviving to delivery.