OOA (Old Order Amish)

Inheritance: autosomal recessive
Genes: TYR

Oculocutaneous albinism type 1B
OCA1B
Yellow albinism
Albinism yellow mutant type
Amish albinism

Hypopigmentation
Iris transillumination
Yellow hair
Amish albinism
Nystagmus
Vision deficit
White hair
Albinotic fundi

Albinism, Oculocutaneous, Type 1B

Clinical Characteristics

General description (for patients):  

Infants appear “white” at birth with no pigmentation in their skin or hair. In this type of albinism skin pigmentation develops in the first few months and the hair turns yellow, hence the name “yellow albinism”.  By the age of two years, the skin appears normal but the hair remains yellow.  The more common type 1A albinism does not show increasing pigmentation.  The iris of the eye appears light blue but sometimes also turns darker.  The absence of pigment in the retina results in vision loss that is not progressive.  Usually nystagmus (“dancing eyes”) is apparent at some point in the first year.

Medical description:  

Newborns with this yellow albinism variant (OCA1B) like OCA1A appear “white” with no pigmentation in skin, iris or hair but by several months of age develop some pigmentation in these structures.  By adolescence, skin pigmentation is normal and individuals tan normally without photosensivity. Diagnosis is still possible in adults though because of the persistence of the albinotic fundi and the characteristic yellow hair color. Retinal hypopigmentation is present from birth and there is no change throughout life.  Visual acuity is usually in the range of 20/200 to 20/400 most likely due to foveal hypoplasia.  This results in poor fixation and nystagmus.  Most individuals also have significant photophobia.  Marked iris translucency present in early childhood decreases as the iris becomes more pigmented with age.  No neurologic or mental abnormalities have been noted.

Genetics:  

This form of albinism is autosomal recessive.  Hair bulb incubation in tyrosine can help distinguish the several types of albinism.  This form, the yellow mutant or type 1B, has hair bulb melanosomes that contain residual amounts of melanin and a slight increase in pigmentation following incubation suggesting some residual tyrosinase activity in contrast to true tyrosinase-negative albinism.  The mutation occurs in the tryrosinase gene (TYR) on chromosome 11 (11q14.q21).  This disorder has been found in the Daviess County, IN, Amish.
TREATMENT:  No treatment for the pigmentary disorder is known.  Lenses with ultraviolet protection and the appropriate refractive correction may be helpful.  Extraocular muscle surgery may be helpful if the patient adopts a head turn to utilize a null point that minimizes the nystagmus.

Prognosis:   

Normal life expectancy.  Lifestyle is primarily impacted by the visual deficit.

Ancillary treatments and support:

Protection from the sun is advised for youngsters until skin pigmentation normalizes.  No reports of skin cancer have appeared.  Low vision evaluation and aids can greatly improve visual functioning.

Specialists and specialty centers:

Pediatrician, ophthalmologist, dermatologist, low vision specialist.

References:

Chiang PW, Drautz JM, Tsai AC, Spector E, Clericuzio CL. A new hypothesis of
OCA1B. Am J Med Genet A. 2008 Nov 15;146A(22):2968-70. PubMed PMID: 18925668.

Nance, W.E., Jackson, C.E., and Witkop, C.J., Jr.:  Amish albinism: a distinctive autosomal recessive phenotype.  Am. J. Hum. Genet.  22: 579-586, 1970.  PubMed ID: 5516239

Tripathi, R.K., Droetto, S., and Spritz, R.A.:  Many patients with ‘tyrosinase-positive’ oculocutaneous albinism have tyrosinase gene mutations.  Am. J. Med. Genet. 51: (abstract) A179, 1992.

Resources:

National Organization for Albinism

Associated Graphics