Oculocutaneous Albinism Test Report

OCULOCUTANEOUS ALBINISM TEST REPORT

Q1This disease is called Oculocutaneous Albinism Type 1 which also includes a sub type of A and B. People with white skin and hair are typical example which is affected by this disease.  Lewis (2013) states that “Oculocutaneous albinism type 1 (OCA1) is characterized by hypopigmentation of the skin and hair and the distinctive ocular changes found in all types of albinism”.  And it is a recessive autosomal. It is caused by an alteration of the tyrosinase gene. As the tyrosinase is the enzyme to control he production of melanin.  For the OCA1A， due to Lewis (2013), “ caused by null mutations of TYR that produce a completely inactive or an incomplete tyrosinase enzyme polypeptide”.  There is not enough TYR enzyme to form the first step of forming the melanin in any melanocyte.  And the OCA1B, “caused by mutations of TYR that produce a partially active or hypomorphic tyrosinase enzyme compound, and heterozygous for two different hypomorphic mutations, or compound heterozygous for a hypomorphic and a null or inactivating mutation. “(Lewis 2013). And the change in polypeptide would also affect the normal function of the protein. Because TRYR is a  “melanosomal membrane bound glycoenzyme with a type-3 copper active site” ( Ray et al. 2007) The lack of melanin would result the normal function affected.

Q2

The aim of using a molecular genetics diagnostic process is to determine the carrier status of individual patients.  NGS-based test would be a way of gene diagnoses which covers the entire field of genes like TYR. This includes all the effect to different types of oculocutaneous albinism which is a general one. It is a molecular and multi-gene panel type by using the method of sequencing and next gen. It mainly has three steps which is the library preparation, amplification and sequencing. (atbio 2014)  For the library preparation is to create the fragment of random DNA with ligand to become a gene library. And the amplification is used to clone amplification methods, including the Emulsion PCR and Bridge PCR. The last one, DNA sequence is used as a different way of test in order to make the result accurate while something wrong with the previous test.  The carrier detecton is also necessary especially for family members. “Molecular genetic testing is not offered routinely to the reproductive partners of family members identified as carriers because of the difficulty of interpreting test results in an unaffected individual with a negative family history.”(Lewis 2013)There might be some errors in the test to drive the result wrong, especially when making the gene library; it is possible to mistake the test gene with the wrong one since it is random.  What’s more, it would also cause some problems with the amplification for it requires the signal from the sequence strong enough to be detected. If the signal is not strong, it would be hard to detect it correctly.