Familial Exudative Vitreoretinopathy (FEVR) is a genetic condition affecting the retina, and its inheritance patterns vary depending on the specific gene involved. The most common forms of FEVR are linked to alterations in the FZD4 or LRP5 genes and exhibit an autosomal dominant inheritance pattern. This means that only one copy of the altered gene in each cell is sufficient to cause the disorder. In autosomal dominant FEVR, affected individuals often inherit the altered gene from a parent, who may or may not show signs or symptoms of the condition.
Illustration of autosomal dominant inheritance
FEVR associated with LRP5 gene variants can also follow an autosomal recessive inheritance pattern. Autosomal recessive inheritance requires that both copies of the gene in each cell have a variant to cause the disorder. In such cases, the parents of an affected individual each carry one copy of the altered gene, but typically do not exhibit symptoms of familial exudative vitreoretinopathy themselves.
Illustration of autosomal recessive inheritance
When familial exudative vitreoretinopathy is caused by variants in the NDP gene, it displays an X-linked recessive inheritance pattern. The NDP gene is located on the X chromosome, one of the two sex chromosomes. In individuals with one X chromosome (typically males), a single altered copy of the gene in each cell is enough to cause the condition. However, in individuals with two X chromosomes (typically females), both copies of the gene would need to be altered to result in the disorder. Consequently, X-linked recessive disorders like familial exudative vitreoretinopathy are more frequently observed in individuals with one X chromosome. A key characteristic of X-linked inheritance is that fathers cannot transmit X-linked traits to their sons.
Illustration of X-linked recessive inheritance
Sex chromosomes, like the X chromosome, play a crucial role in genetic inheritance. Understanding the different inheritance patterns associated with familial exudative vitreoretinopathy is essential for genetic counseling and family planning.
