Shortage or excess of dopamine can prevent proper function and signaling of these receptors leading to disease states.Apomorphine improves motor function by activating dopamine receptors in the nigrostriatal pathway, the limbic system, the hypothalamus, and the pituitary gland. It also increases blood flow to the supplementary motor area and to the dorsolateral prefrontal cortex (stimulation of which has been found to reduce the tardive dyskinesia effects of L-DOPA). Parkinsons has also been found to have excess iron at the sites of neurodegeneration; both the (R)- and (S)-enantiomers of apomorphine are potent iron chelators and radical scavengers.Apomorphine also decreases the breakdown of dopamine in the brain (though it inhibits its synthesis as well). It is an upregulator of certain neural growth factors, in particular NGF but not BDNF, epigenetic downregulation of which has been associated with addictive behaviour in rats.Apomorphine causes vomiting by acting on dopamine receptors in the chemoreceptor trigger zone of the medulla; this activates the nearby vomiting center. Pharmacokinetics
While apomorphine has lower bioavailability when taken orally, due to not being absorbed well in the GI tract and undergoing heavy first-pass metabolism, it has a bioavailability of 100% when given subcutaneously. It reaches peak plasma concentration in 10–60 minutes. Ten to twenty minutes after that, it reaches its peak concentration in the cerebrospinal fluid.
Online Mendelian Inheritance in Man (OMIM): 106210 AN
Online Mendelian Inheritance in Man (OMIM): 106220 Aniridia and absent patella
Online Mendelian Inheritance in Man (OMIM): 106230 Aniridia, microcornea, and  spontaneously reabsorbed cataract
Online Mendelian Inheritance in Man (OMIM): 206700 Aniridia, cerebellar ataxia, and mental deficiency (Gillespie syndrome)

Mutational analysis
Molecular (DNA) testing for PAX6 gene mutations (by sequencing of the entire coding region and deletion/duplication analysis) is available for isolated aniridia and the Gillespie syndrome. For the WAGR syndrome, high-resolution cytogenetic analysis and fluorescence in situ hybridization (FISH) can be utilized to identify deletions within chromosome band 11p13, where both the PAX6 and WT1 genes are located. Symptoms
Aniridia can cause many symptoms, such as:

Poor vision (not always present)
More sensitivity to light
Fast, uncontrolled, shaking "to and from" eye movements (nystagmus)
Eyes dont line up (strabismus)

Treatment
In May 2018, the U.S. Food and Drug Administration approved the CustomFlex Artificial Iris, the first synthetic iris for use in adults and children with congenital aniridia or iris defects related to other conditions, such as albinism, traumatic injury, or surgical removal due to ocular melanoma. The artificial iris is a surgically implanted device made of thin, foldable, medical-grade silicone and is custom-sized and colored for each individual patient. The prosthetic iris is held in place by the anatomical structures of the eye or, if needed, by sutures. See also
WAGR syndrome
Scleral lenses

References
External links

GeneReviews/NCBI/NIH/UW entry on Aniridia
NCBI/Molecular diagnosis of aniridia
OMIM entries on Aniridia
GeneReviews/NIH/NCBI/UW entry on Wilms Tumor Overview