Important syn
A characteristic of X-linked inheritance is that fathers cannot pass X-linked traits to their sons. In females (who have two X chromosomes), a mutation in one copy of the COL4A5 gene usually only results in hematuria, but some women experience more severe symptoms. In males (who have only one X chromosome), one altered copy of the COL4A5 gene in each cell is sufficient to cause kidney failure and other severe symptoms of the disorder. This gene is located on the X chromosome, which is one of the two sex chromosomes. About 80 percent of cases are caused by mutations in the COL4A5 gene and are inherited in an X-linked pattern. Mutations that disrupt type IV collagen can result in misshapen lenses and an abnormally colored retina.Īlport syndrome can have different inheritance patterns. In the eye, this protein is important for maintaining the shape of the lens and the normal color of the retina. Alterations in type IV collagen often result in abnormal inner ear function, which can lead to hearing loss. Type IV collagen is also an important component of inner ear structures, particularly the organ of Corti, that transform sound waves into nerve impulses for the brain. Gradual scarring of the kidneys occurs, eventually leading to kidney failure in many people with Alport syndrome. Mutations in these genes result in abnormalities of the type IV collagen in glomeruli, which prevents the kidneys from properly filtering the blood and allows blood and protein to pass into the urine. Glomeruli are clusters of specialized blood vessels that remove water and waste products from blood and create urine. This protein plays an important role in the kidneys, specifically in structures called glomeruli. These genes each provide instructions for making one component of a protein called type IV collagen. Mutations in the COL4A3, COL4A4, and COL4A5 genes cause Alport syndrome. Significant hearing loss, eye abnormalities, and progressive kidney disease are more common in males with Alport syndrome than in affected females. These eye abnormalities seldom lead to vision loss. Affected individuals may also have misshapen lenses in the eyes (anterior lenticonus) and abnormal coloration of the light-sensitive tissue at the back of the eye ( retina ). People with Alport syndrome frequently develop sensorineural hearing loss, which is caused by abnormalities of the inner ear, during late childhood or early adolescence. The kidneys become less able to function as this condition progresses, resulting in end-stage renal disease (ESRD). Many people with Alport syndrome also develop high levels of protein in their urine (proteinuria). Almost all affected individuals have blood in their urine (hematuria), which indicates abnormal functioning of the kidneys. People with Alport syndrome experience progressive loss of kidney function. Alport syndrome is a genetic condition characterized by kidney disease, hearing loss, and eye abnormalities.
