Dr. Zuhal Butuner Talks About Ophthalmic Genetic Disorders

Our genes and associated proteins are foundational to our physical and mental makeup, determining many distinct traits and characteristics. Despite this, these genetic components may also harbor mutations that can adversely affect our lifelong health. These mutations may be inherited through our parental chromosomes or arise spontaneously. Genetic disorders occur when these mutations alter the resulting proteins in detrimental ways. These mutations may manifest in either the heterozygous or homozygous states, affecting one or both alleles accordingly. Dr. Zuhal Butuner emphasizes that understanding how these mutations impact our ocular and systemic health can be vital in preventing and addressing genetic disorders in the future.

In addition, some disorders require the additive effect of mutations in several genes, or they require an environmental component to become manifest. These are then referred to as polygenic or multifactorial disorders. Among the 6,000 known human genetic diseases, roughly one-third are solely ocular or present ocular symptoms.

Disease development is a complex process that often involves mutations in multiple genes. The significance of each gene can be reduced in these cases, as the interaction and combination of mutations play a crucial role in developing certain diseases. For instance, retinitis pigmentosa, a group of rare genetic disorders that cause retina degeneration, has been linked to mutations in over 200 genes. Mutations in several of these genes may lead to different phenotypes, such as macular degeneration, night blindness, or the severe inherited retinal disease known as Leber congenital amaurosis. Therefore, understanding how mutations in multiple genes contribute to disease development is crucial for effective diagnosis and the development of treatments. It is worth noting that a person’s genome comprises two strands, a maternal and a paternal, each containing three billion base pairs and organized as chromosomes.

Dr. Zuhal Butuner explains that a thorough ophthalmologic examination helps confirm the diagnosis of genetic eye diseases. This examination is just a piece of a larger genetic workup that includes constructing a pedigree to show genetic relationships and medical histories within a family. By studying this pedigree, patterns of transmission of familial disorders may become evident, leading to a more refined diagnosis and risk assessment for family members. Further refinements can be made through chromosomal or molecular analysis to search for gene mutations, potentially specifying the disease subtype. Patients must undergo this comprehensive evaluation to ensure proper treatment and management of their condition.

A broad array of hereditary eye disorders have been identified, including conditions limited to the eye and complex syndromes with ocular manifestations. Heritable conditions such as congenital cataracts and retinal degeneration are among the leading genetic causes of blindness.

Congenital cataracts present at birth affect roughly one in 250 newborns, while others develop later in life in association with other underlying genetic disorders. Hereditary retinal degenerations include a group of eye disorders called retinitis pigmentosa (RP), which affects approximately one in 5,000 people in the United States. RP commonly onsets during the first two decades of life, with the severity of the disorder varying between subtypes and modes of transmission. For some individuals, RP can progress to severe vision loss by the fourth or fifth decade of life. Another common inherited retinal disease is Juvenile Macular Degeneration or Stargardt disease.

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