OCA Type 1A is an autosomal recessive condition, meaning there is a homozygous or compound heterozygous mutation related to the TYR gene. There are many different types of albinism, differing due to the effects of various mutations. Oculocutaneous albinism type IA is the most severe type of albinism, as it is characterized by no melanin production. Other types of albinism have limited melanin production. Because type IA Albinism has no functioning copies of the gene, it is the most severe type of albinism. The mutations on this gene lead to a complete lack of tyrosinase activity as the inactive enzyme is produced. An inactive enzyme can be caused by a missense or nonsense mutation. Due to the lack of enzymes needed to catalyze the production of melanin, patients do not have melanin protecting them from the sun, resulting in sensitive eyes, skin, and other symptoms mentioned in the signs and symptoms of OCA1A. The different forms of albinism and range of severity is dependent upon the level of melanin production, which depends on the level of tyrosinase activity. Diagnosis
Because albinism is autosomal recessive, prenatal genetic screening and genetic counseling can be performed to diagnose OCA early on. When pathogenic variants are known to be present in an affected family, carrier testing can also be conducted. The level of expression can be variable depending on the pigmentation background, so phenotypically, OCA can be expressed on a spectrum. OCA is heterogenous, with OCA1 being caused by a mutation in the TYR gene.
History
Edwards syndrome was first identified by John Hilton Edwards in 1960, although he originally believed it to be caused by a trisomy of chromosome 17. Klaus Patau and Eeva Therman reported another two cases shortly thereafter. They identified the extra chromosome as being part of what Pataus lab called "group E", containing chromosomes 16, 17, and 18, but were unable to determine which chromosome was responsible at the time. Analyzing 5 more cases, they were able to determine that the extra chromosome was in fact chromosome 18. See also
18q deletion syndrome

References
External links

Edwards syndrome at Curlie
Perinatal Hospice Care - Preparing for birth and death"
Humpath #5389