text: STRA6 can be found at high levels in various tissues including: the choroid plexus, the brain microvascular, tesis, the spleen, kidney, eye, the placenta, and the female reproductive tract.  However, it is surprisingly not found in liver tissue where Vitamin A (retinol) is primarily stored. Because of its importance in Vitamin A transport, STRA6 mutations are more commonly associated with problems with eye such as a reduction in retinal thickness and shortening of the inner and outer segments of rod photoreceptors.   Therefore, as might be expected, STRA6 mutations result in a number of different abnormalities of the eye such as Microphthalmia, Anophthalmia, and Coloboma.
  However, STRA6 is clearly vital for more than just eye development as it is expressed in many different tissues detailed above.  Other disorders that result from STRA6 mutations include pulmonary dysgenesis, cardiac malformations, and mental retardation. In fact, research has shown that homozygous mutations in human STRA6 gene can lead to Matthew-Wood syndrome, which is a combination of all the mentioned disorders.  In this respect, STRA6 mutations can be particularly fatal during the embryonic stage.
  STRA6 has also been associated with facilitating insulin resistance.  This is because STRA6 signaling results in activation of transcription factor STAT5 target genes.  One of these target genes is a suppressor of cytokine signaling 3 (SOCS3) which is a strong inhibitor of insulin signaling.  As a result, STRA6 signaling suppresses the response to insulin by inhibiting the phosphorylation of the insulin receptor, IR, by an influx of insulin. In other words, increased levels of the RBP in obese animals (which will increase STRA6 activity) can facilitate insulin resistance.  Due to this close relationship between STRA6 and insulin resistance, it has been demonstrated that single nucleotide polymorphisms in STRA6 are associated with Type 2 Diabetes.