Microphthalmia is an inherited disease affecting the Soft Coated Wheaten Terrier breed. Affected puppies are born with very small eyes and anatomical defects, resulting in blindness that is incurable.
The disease is caused by a mutation in the RBP4 gene which causes deficiency in vitamin A during gestation and as a result maternal vitamin A is not transported to the developing puppies.
Genetically affected puppies (RBP4/RBP4) will only develop microphthalmia if their dam is also genetically affected (RBP4/RBP4) by this disease. If the dam is carrier (N/RBP4) of the mutation, then her genetically affected puppies (RBP4/RBP4) are unlikely to develop the disease.