MOLECULAR STUDY OCULAR ALBINISM TYPE I, GPR143 GENE , SEQUENCING, WHOLE BLOOD

New Test in CIC Catalog

Test Code: 4171

Sample:	Whole blood - EDTA (5 ml)
Conservation:	Refrigerated
Method:	Sequencing Method
Set Up Days:	Daily
Plazo de Entrega:	32 days
Information:
X-linked ocular albinism (XLOA) is a disorder of melanosome biogenesis leading to minor skin manifestations and congenital and persistent visual impairment in affected males. XLOA is characterized by infantile nystagmus, reduced visual acuity, hypopigmentation of the iris pigment epithelium and the ocular fundus, and foveal hypoplasia. Significant refractive errors, reduced or absent binocular functions, photoaversion, and strabismus are common. XLOA is a non-progressive disorder and the visual acuity remains stable throughout life, often slowly improving into the mid-teens. XLOA is inherited in an X-linked manner. An affected male transmits the disease-causing mutation to all of his daughters and none of his sons. The risk to the sibs of a male proband depends on the carrier status of the mother. If the mother is a carrier, the chance of transmitting the GPR143 mutation in each pregnancy is 50%. Male sibs who inherit the mutation will be affected; female sibs who inherit the mutation will be carriers and will usually not be affected. Carrier testing of at-risk female relatives is possible if the mutation has been identified in the proband. If the familial mutation is not known because an affected male is unavailable for testing, molecular genetic testing can be performed on at-risk female relatives, but with a lower degree of test sensitivity. Prenatal testing is possible for pregnancies at increased risk if the familial mutation is known. Molecular genetic testing of GPR143 detects mutations in more than 90% of affected males. Sequencing and deletion/duplication analyses of the GPR143 coding region are available clinically. Together, such testing is expected to detect more than 90% of hemizygous mutations in affected males. About 48% of reported mutations are intragenic deletions and about 43% are point mutations. Lack of amplification by PCR prior to sequence analysis can suggest a putative exonic or whole-gene deletion on the X chromosome in affected males; confirmation may require additional testing by deletion/duplication analysis.
Links:
Ocular Albinism, X-Linked - GeneReviews™ - NCBI Bookshelf
OMIM Entry - # 300500 - ALBINISM, OCULAR, TYPE I; OA1
OMIM Entry - ^ 300800 - MOVED TO 103580

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