What is albinism?
Albinism is a genetic disease that manifests as a lack of pigmentation of the skin, eyes, hair, etc., due to mutations in various genes that result in defects in melanin or melanosome biosynthesis. Albinism was first described in official medical records in 1908 by Archibald Garrod, a famous British physician and geneticist, who is therefore known as the “father of albinism”. Albinism is also known as the child of the moon because of its photophobic symptoms and relative comfort during nighttime activities. The average incidence of albinism in the population is 1:15,000, so it is estimated that there are about 90,000 albinos in our population, and on average one in 60 people carry the albinism gene without showing symptoms.
How is albinism inherited?
Albinism is generally inherited in an autosomal recessive manner, and consanguineous marriages can increase the risk of the disease. This means that both parents carry the albinism gene and do not develop the disease themselves. If both parents pass the gene to their children, they will develop the disease, and the chances of both sexes developing the disease are equal, with a 1 in 4 chance of this happening.
One type of albinism, known as ocular albinism, which is predominantly eye damage, is X-linked recessive and develops when the albinism gene is passed from mother to son and not usually to daughter, with a probability of 1/2. This type accounts for a relatively small percentage of all albinism types.
What are the major types of albinism?
There are many ways to classify albinism. Depending on the site of involvement, albinism is divided into two categories: oculocutaneous albinism and ocular albinism. According to the presence or absence of concomitant symptoms, albinism can be divided into syndromic and non-syndromic (also called simple) albinism. Tyrosinase positive or negative albinism is classified according to the presence or absence of residual tyrosinase activity in melanocytes.
What are the genes that cause albinism?
In recent years, there are at least 18 genes that cause generalized albinism and at least 8 genes that cause localized albinism. There is a possibility that new albinism genes will be discovered one after another.
What are the clinical manifestations of albinism?
Albinism is characterized by reduced melanin in the skin, sensitivity to ultraviolet light, and susceptibility to skin cancer. The clinical manifestations of albinism vary among subtypes. Most patients’ life expectancy and intelligence are not affected, etc. Some severe albinos may show bleeding tendencies, pulmonary fibrosis, colitis, and symptoms of nerve damage. Some albinos have immune deficiencies that can make them susceptible to infections.
How is albinism diagnosed?
The diagnosis of albinism is based on the signs and symptoms of the eyes. Genotyping of the various subtypes is critical. Genetic diagnosis is currently the most reliable method for differential and prenatal diagnosis. Genetic diagnosis of some albinism subtypes may be difficult because their pathogenesis has not been elucidated.
Are there any prevention and treatment options for albinism?
The main risk of albinism is damage to vision. A very small percentage of albinos can die at an early or middle age due to complications of immunodeficiency or pulmonary fibrosis, and is one of the serious genetic diseases requiring intervention. In addition to symptomatic treatment, there is no cure for albinism, and prevention is the main focus. Preventing the birth of a child with albinism is the main preventive measure.
Genetic diagnosis of albinism In cooperation with the Institute of Genetics and Developmental Biology of the Chinese Academy of Sciences, our dermatology clinic has established a series of diagnostic methods for the genes of common albinism, specifically to provide clinical diagnosis, genetic counseling and necessary treatment for albinism patients and susceptible people.
Determination of the genetic type of those already affected to guide symptomatic treatment and to understand the prognosis.
Prenatal diagnosis to guide eugenics.
Genetic diagnosis of albinism is performed by collecting 2 to 4 ml of peripheral blood from the patient who applies for genetic diagnosis of albinism, and by performing clinical typing through genetic counseling and necessary tests before genetic diagnosis. The currently adopted albinism genetic screening protocol can generally make accurate genotyping diagnosis for more than 90% of patients or carriers, and the results of gene mutations are confirmed by gene sequencing.