1 / 9

Oculocutaneous albinism type 1A

Oculocutaneous albinism type 1A. Adrienne Bonvini. What is it?. It is an autosomal recessive disorder characterized by an absence of pigment in the eyes, hair, and skin.

eryk
Download Presentation

Oculocutaneous albinism type 1A

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Oculocutaneous albinism type 1A Adrienne Bonvini

  2. What is it? • It is an autosomal recessive disorder characterized by an absence of pigment in the eyes, hair, and skin. • This specific type is characterized by complete lack of tyrosinase activity because an inactive form of the enzyme is produced. • Occurs at a rate of 1/40,000 people

  3. Clinical Features • Reduced synthesis of melanin in the skin, hair, and eyes. • Translucent irises • Vision usually in the range of 20/100 to 20/400

  4. Molecular Genetics • OCA1A is caused by mutations of the TYR gene that produce a inactive form of the tyrosinase enzyme. • Parents of an affected child are considered to be obligate heterozygotes, each carrying a single copy of the disease-causing mutation in the TYR gene. • The gene is located on chromosome 11, at 11q14 – q21 • The lack of this enzyme blocks the first step of the melanin biosynthetic pathway, and no melanin is formed in the appropriate melanocytes.

  5. Molecular genetic testing • There is evidence of undetected mutations that may be responsible for OCA1. This evidence is from people with the OCA1A pheotype with only a single identifiable mutation, who are most likely compound heterozygotes with a second mutation that has yet to be identified.

  6. Mutations of the TYR gene • Missense subsitutions in the tyrosinase gene alters codons 355 (thr to lys) and codon 365 (asp to asn). These mutations cause the tyrosinase activity to be disrupted, causing the lack of pigmentation seen in albinism. Both of these mutations occur in the copper binding region of the enzyme.

  7. Visualization of mutations • thr to lys  asp to asn 

  8. An example of a tyrosinase

  9. Bibliography • http://www.rcsb.org/pdb/explore/explore.do?structureId=1WX2 • http://www.ncbi.nlm.nih.gov/entrez/dispomim.cgi?id=606933&a=606933_AllelicVariant0003 • http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=gene&cmd=Retrieve&dopt=full_report&list_uids=7299 • http://www.ncbi.nlm.nih.gov/entrez/dispomim.cgi?id=203100

More Related