| Identifier |
Oculocutaneous_Albinism_1080p |
| Title |
Oculocutaneous Albinism |
| Creator |
Andrew G. Lee, MD; Israa ShwaikI |
| Affiliation |
(AGL) Chairman, Department of Ophthalmology, The Methodist Hospital, Houston, Texas; Professor of Ophthalmology, Weill Cornell Medicine, New York City, New York; (IS) Baylor College of Medicine, Houston, Texas |
| Subject |
Melinin; Illumination Defects |
| Description |
Dr. Lee lectures medical students on the subject of oculocutaneous albinism. |
| Transcript |
So today we're going to be talking about oculocutaneous albinism, which is normally a retinal problem. And so, I'm only going to be talking about the neuro-ophthalmology ways oculocutaneous albinism comes to us as well as ocular albinism, which is a lot harder obviously. Oculocutaneous albinism is usually an easy diagnosis to make because you don't have any melanin. And if you don't have any melanin, then your hair is going to be white, and your skin is going to be white, and your iris is going to be blue, and there is going to be trans-illumination defects. And that melanin is also going to be a problem in the back of the eye because you're going to have a very pale-appearing fundus and visible choroid underneath the retinal pigment epithelium because you don't have good pigment. And there's going to be foveal hypoplasia, so that is going to cause decreased vision, and normally the vision is like in the 20/200 level range and it's bilateral and symmetric. So there's not going to be a RAPD, and they're going to have nystagmus. So that's really how it comes to me: it's an infant with nystagmus; they can have strabismus as well and that doesn't have to be a sensory strabismus, it could just be a congenital infantile esotropia. And the patient will have all of this identified at birth. Their is is going to show a transillumination defect and with retroillumination we'll be able to see right through their is. It's autosomal recessive, and that means the patients usually don't have a family history either in the generation above them or the generation below them. That means twenty-five percent though of the siblings might be affected. And there are a number of genes that cause oculocutaneous albinism, of which the major ones one through seven the problem is in tyrosinasein the conversion of tyrosinetodopa, and that is required for the formation of melanin in the melanosome and in the melanocyte. Even the number of melanocytes is normal. In addition because you don't have any melanin you're going to be susceptible to ultraviolet damage (UVa damage), and so all of these people have to wear sunscreen and be out of the sun. They often have actinic keratosis and can have malignancies of the skin: squamous cell carcinoma. It tends to be very aggressive type of skin cancers. Ironically, they really don't get melanoma because they don't have any melanin so it's the skin cancers that we normally are dealing with (squamous cell, basal cell carcinoma)that are the things that cause the morbidity and sometimes the mortality in oculocutaneous albinism. The harder one is ocular albinism, where their skin is normal and their hair is normal because it's only the melanin in the eye. Otherwise, they have the same features: the nystagmus, the strabismus, the transillumination defects and the foveal hypoplasia. And so any kid who has nystagmus you have to look at their iris for transillumination defects even if they don't have the cutaneous manifestations of albinism because it could just be the ocular albinism. This is a different gene and the X-linked form is the most common form of ocular albinism. You should also know that the autosomal recessive oculocutaneous albinism have syndromic and non-syndromic forms. The syndromic forms that matter to neurop are Chediak-Higashi and Hermansky-Pudlak. The reason you need to know these is these have systemic manifestations including immunologic disorders, neutropenia. And in Hermansky-Pudlak, there's a very large family from Puerto Rico so we should ask them if they're Puerto Rican in ethnicity and they might have pulmonary fibrosis or granulomatous colitis in the Hermansky-Pudlak version. The hematologic and immunologic abnormalities in the Chediak-Higashi syndrome also can lead to recurrent infections and you need to know about both Chediak-Higashi and Hermansky-Pudlak as systemic manifestations of oculocutaneous albinism that could present with deficits in granulocytes and in platelets that could cause easy bleeding, and hematologic abnormalities in the Chediak-Higashi syndrome as well as the immunologic abnormalities in the Hermansky-Pudlak disorder. And then finally the last thing you need to know about neurop with the oculocutaneous albinism is the crossing in the chiasm is not right and they get this over-decussation in the chiasm. It's of academic interest only but you should know it because it often appears on tests of various types that you should know that the crossing and the decussation is not normal in albinism. So you need to know a little bit about oculocutaneous albinism. |
| Date |
2021-06 |
| Language |
eng |
| Format |
video/mp4 |
| Type |
Image/MovingImage |
| Collection |
Neuro-Ophthalmology Virtual Education Library: Andrew G. Lee Collection: https://novel.utah.edu/Lee/ |
| Publisher |
North American Neuro-Ophthalmology Society |
| Holding Institution |
Spencer S. Eccles Health Sciences Library, University of Utah |
| Rights Management |
Copyright 2019. For further information regarding the rights to this collection, please visit: https://NOVEL.utah.edu/about/copyright |
| ARK |
ark:/87278/s6z37zf9 |
| Setname |
ehsl_novel_lee |
| ID |
1701576 |
| Reference URL |
https://collections.lib.utah.edu/ark:/87278/s6z37zf9 |
