Albinism (albinism) is a relatively common disease caused by a lack of melanin in the skin and its accessory organs. It is a genetic leukomalacia caused by a congenital lack of tyrosinase, or hypotyrosinase function, and impaired melanin synthesis. These patients usually have a lack of melanin in the skin, hair, and eyes of the whole body, so they manifest as retinal pentapigmentation of the eyes, pale pink color of the iris and pupils, fear of light, and always squinting when looking at things. The skin, eyebrows, hair and other body hair are white or yellowish in color. These patients are commonly referred to as “sheep with white heads”. Albinism runs in families and is an autosomal recessive disease, often occurring in people who are married to close relatives.
Symptoms and signs The albino skin lacks melanin and is creamy white or pink, soft and dry. The hair becomes pale white or yellowish. Due to the lack of melanin protection, the patient’s skin is highly sensitive to light and is prone to sun spots and various photosensitive dermatitis after sun exposure without darkening the skin after sun exposure. Photodermatitis, capillary dilation and solar keratosis also often occur, and basal cell carcinoma or squamous cell carcinoma may occur. The iris is pink or light blue due to lack of pigmentation, and there are often symptoms such as photophobia, lacrimation, nystagmus and astigmatism. Most albinos have poor physical and mental development Treatment Currently, medication is ineffective and only physical methods, such as shading, can be used to reduce the patient’s discomfort. Treatment with photosensitizing drugs and hormones can also be used to reduce or even eliminate the white spots.
The diagnosis of genetic diagnosis of albinism is mainly based on the signs and symptoms of the eyes. Differential diagnosis of the various subtypes is critical. Tyrosinase activity measurement helps in its classification and diagnosis. Genetic diagnosis is currently the most reliable method for differential and prenatal diagnosis. Genetic diagnosis of some albinism subtypes may be difficult because their pathogenic mechanisms have not been elucidated. There is no cure for albinism except symptomatic treatment, so prevention should be the main focus, i.e., prohibition of consanguineous marriage through genetic counseling is one of the important preventive measures, and prenatal genetic diagnosis is also an important safeguard to prevent the birth of children with this disease. Prevention should be based on minimizing damage to the eyes and skin from UV radiation.
Pathogenesis Early researchers had many different theories about the cause of albinism, but none of them were quite correct. It was not until the early twentieth century that scientists were truly certain that albinism was due to an abnormality in the gene that controls tyrosinase, an inborn metabolic abnormality with a defect in the melanogenesis process, a somatic recessive disorder that is monogenic (tyrosinase converts tyrosine into melanin). The melanin that is missing in albinos is produced in melanocytes.
The normal function of human melanocytes, which are mainly found in the skin, hair follicles and eyes, is closely related to the activity of tyrosinase, which is the raw material for melanin formation and requires tyrosinase as the locomotive to catalyze a series of biochemical reactions; because the melanin production process is quite complex, it often involves lesions in other organ systems, such as The process of melanin production is complex and often involves lesions in other organ systems, such as abnormalities in the course of optic nerve fibers, hemorrhagic tendencies, immune abnormalities, and waxy lipid accumulation (a rare fatty lesion); however, other than optic neuropathy, these are quite rare. This reflects the fact that genes control the metabolic processes and thus the traits of the organism by controlling the synthesis of enzymes.
Disease diagnosis Diagnosis is based on congenital onset and clinical manifestations. Pure white or pink spots are present at birth and are prone to dermatitis after sun exposure, with distinct local boundaries. Histopathology shows the presence of clear cells in the basal layer, with normal number and appearance. Silver staining demonstrates a lack of melanin in the epidermis; hair turns white or yellowish; iris is pink, pupils are red and photophobic.
Examination methods Laboratory tests: genetic examination, tumor marker examination.
Other auxiliary examinations: histopathological examination.