Cataracts 13, Congenital, in Adult i RBC Phenotype

Background and History: 

Red blood cells have receptor proteins on their cell surfaces (such as ABO or Rh) which are genetically determined.  This condition is one of several in which a specific type of receptor is associated with cataracts (opacities in the lens of the eye).

Clinical Correlations: 

Cataracts are often detected at birth.  There are no other consequences of the gene mutation.


The biochemical mechanism(s) causing the cataracts is unknown. However, individuals with a specific configuration of the iI blood group in which the fetal form persists into adulthood are susceptible (particularly Asians) to the development of cataracts.

This type of cataract requires that both copies of a specific gene are changed (mutated).  Carrier parents with only one mutation do not have cataracts but if both such parents contribute a single mutation the child who inherits these will likely have cataracts.  The risk for each child of such a couple is 25%.

Diagnosis and Prognosis: 

The diagnosis of cataracts is usually made by an ophthalmologist following the detection of a white appearance of the pupil by pediatricians or others.  A complete eye examination is necessary since there are other causes of a white pupillary reflex, among them tumors such as a retinoblastoma (tumor of the retina).

The general prognosis is good since there are no other signs in the rest of the body.  Congenital cataracts if sufficiently dense need to be surgically removed as soon as possible to prevent a lazy eye (amblyopia).

Additional Information
Autosomal recessive