Oculocutaneous Albinism - Causes, Symptoms, Diagnosis, and Treatment

Introduction

Oculocutaneous albinism is a group of rare hereditary diseases that affects the color (pigmentation) of skin, hair, and eyes. A reduced or complete lack of melanin pigment characterizes this disease. This condition is caused when a mutation happens in specific genes responsible for the production of melanin pigment in melanocytes. Melanocytes are the cells that produce melanin. The reduction or lack of melanin leads to abnormal eye and skin development. There will be abnormalities in vision, nystagmus (eyes make rapid, repetitive movements), strabismus (crossed eyes), and photophobia (sensitivity to light).

In contrast, in the skin, the skin becomes very light that gets damaged even in sunlight, and skin cancer. All these abnormalities vary in their severity depending on their type. In addition, the types of oculocutaneous albinism vary depending on their mutation. Oculocutaneous albinism is an autosomal recessive genetic condition.

What Are the Alternative Names for Oculocutaneous Albinism?

• Minimal oculocutaneous albinism.

• Brown oculocutaneous albinism.

• Platinum oculocutaneous albinism.

• Temperature-sensitive oculocutaneous albinism.

• Rufous oculocutaneous albinism.

• Tyrosinase negative oculocutaneous albinism.

• Tyrosinase-positive oculocutaneous albinism.

• Tyrosinase-related oculocutaneous albinism.

• Yellow oculocutaneous albinism.

What Are the Types of Oculocutaneous Albinism?

Oculocutaneous albinism is classified into seven types. Each of these is caused due to the mutation of seven different genes. They are:

• Oculocutaneous Albinism Type IA (OCA1A) - Individuals are presented with a complete absence of melanin pigment, resulting in completely white hair and skin at birth and the iris not getting darker. They may also present with visual acuity. It is caused by the mutation of the tyrosinase gene, which produces the key enzyme for melanin pigment production.

• Oculocutaneous Albinism Type IB (OCA1B) - In this type of oculocutaneous albinism, patients have white or light-yellow hair at birth that can become darker over time. Iris may change from light blue to green or brown color. Vision is better when compared with OCA1A. The mutation of the tyrosinase gene also causes it, but the enzyme activity is a little less in this type.

• Oculocutaneous Albinism Type II (OCA2) - In type 2, hair and skin pigment is not completely absent. They usually present with partial pigmentation. Individuals with more sun exposure may develop dark spots on their skin. Due to sun exposure, these dark spots are pigmented nevi and lentigines. These dark spots do not appear in other types of oculocutaneous albinism. This type is also called brown oculocutaneous albinism. The mutation of the OCA2 gene causes it to be called the p gene, which is responsible for the production of the OCA2 protein. The main function of this protein needs to be evident.

• Oculocutaneous Albinism Type III (OCA3) - In this type, the people have reddish-brown skin, reddish hair, and brown eyes. It is termed as rufous albinism. It is caused by the mutation of the tyrosinase-related protein one gene, which is responsible for the production of an enzyme like tyrosinase enzyme that is involved in the production of melanin pigment. It is the later step after the tyrosinase initiation.

• Oculocutaneous Albinism Type IV (OCA4) - In this type, the features are similar to OCA2. It is caused by the mutation of the SLC45A2 gene, which is also responsible for the production of melanin pigment.

• Oculocutaneous Albinism Type V (OCA5) - This type is a rare type that is found only in one family from Pakistan. The patient presented with golden color hair, white skin, and visual abnormalities similar to OCA1. The specific gene which causes this type is located on chromosome 4, where 14 genes are located in the same place. The causative gene is not determined.

• Oculocutaneous Albinism Type VI (OCA6) - In this type, individuals are presented with light to dark brown hair, white skin, and brown iris. It is caused by the mutation of the SLC24A5 gene, which is responsible for producing membrane associate transporter protein. The function of this protein is not determined.

• Oculocutaneous Albinism Type VII (OCA7) - The patients are presented with dark brown hair and hypopigmented skin. They have nystagmus and iris illumination. The mutation of C10 or f11 genes causes it.

What Causes Oculocutaneous Albinism?

Oculocutaneous albinism is caused by the mutation of genes in the protein (melanin), which is produced by melanocytes. Melanin is a protein responsible for pigmentation (coloring) of the hair, skin, and eyes. The melanin pigment has two types: brown-black, eumelanin, and yellow-red pheomelanin. Every melanin pigment in the body combines these two types of pigment. Therefore, the mutation of genes in melanin causes a reduction or complete lack of melanin.

The seven types of oculocutaneous albinism are caused by the mutation of seven genes, as mentioned in the types of oculocutaneous albinism.

What Are the Signs and Symptoms of Oculocutaneous Albinism?

The major ones are visual problems, such as:

• Nystagmus (involuntary side-to-side movement of eyes).

• Strabismus (crossed eyes).

• Iris illumination.

• Reduced retinal pigment.

• Lack of development of macula.

• Poor visual acuity.

• Photophobia.

In addition to this, it also affects the skin, which leads to skin cancer. The color of hair varies for different types of oculocutaneous albinism.

What Are the Diagnostic Methods for Oculocutaneous Albinism?

Oculocutaneous albinism is diagnosed by the clinical findings of hypopigmentation found on hair, skin, and eyes when a patient contacts the doctor. In addition, molecular genetic testing is necessary to find which type of oculocutaneous albinism the person has.

Prenatal diagnosis is possible if there is an affected person in the family. Pregnant women should undergo prenatal diagnosis with careful genetic counseling to the parents. Usually, oculocutaneous albinism is diagnosed in the newborn.

What Is the Treatment for Oculocutaneous Albinism?

If oculocutaneous albinism is diagnosed, the person should visit an ophthalmologist immediately to find the severity of the condition. Visual abnormalities are correct through the contact lens and spectacles. Visual acuity will improve with age, so a regular visit to the ophthalmologist is advised. Dark glasses will help people with sunlight sensitivity. Affected individuals should protect their skin from the sun by covering it with clothes and using sunblocks to prevent sunburn, dark spots on the skin, and skin cancer.

What Is the Differential Diagnosis for Oculocutaneous Albinism?

• Ocular albinism.

• Hermansky-Pudlak syndrome.

• Chediak-Higashi syndrome.

• Griscelli syndrome.

• Waardenburg syndrome type II.

• Congenital motor nystagmus.

These are the differential diagnosis for oculocutaneous albinism.

Conclusion

Oculocutaneous albinism is not a life-threatening genetic condition. However, the chances of developing skin cancers and visual abnormalities are high. So people are advised to go for a regular check-ups for skin and eyes.