Renal coloboma syndrome ..., (papillorenal syndrome) (Renal coloboma syndrome) - Gen PAX2.

Renal coloboma syndrome (also known as papillorenal syndrome) is a condition that mainly affects the kidney and eye development. People with this condition often have hypoplasia, which can lead to end stage renal disease (ESRD). It has been estimated that approximately ten percent of children with renal hypoplasia may have renal-coloboma syndrome. Kidney problems can affect one or both kidneys. Furthermore, people with Down syndrome may have a defect in the optic nerve, sometimes associated with a hole, or coloboma in the retina. Vision problems caused by these abnormalities , may vary depending on the size and location of the malformation. Some people have no vision problems, while others may have serious vision problems. Less common features include vesicoureteral reflux syndrome, presence of multiple renal cysts, and a mild hearing loss.

This process is due to mutations in the PAX2 gene, located on the long (q) arm of chromosome 10 (10q24). This gene encodes a protein that is involved in the early development of the eye, ear, the central nervous system, kidney and genital tract. The PAX2 gene belongs to a gene family involved in formation of tissues and organs during embryonic development. Family members of PAX genes are also important for maintaining normal function of certain cells after birth. To perform these functions, the PAX genes encode proteins that bind to specific areas of DNA and help control the activity (expression) of some genes. Based on this action, the PAX proteins are called transcription factors.

There are more than 20 mutations in the PAX2 gene, which cause renal coloboma syndrome. Mutations in the PAX2 gene, leading to production of a nonfunctional protein which is unable to participate in the development, causing incomplete formation of certain tissues. Most mutations occur in the region of the protein that binds to DNA, affecting its function as a transcription factor. The lack of functional proteins disrupts the formation of certain tissues (especially the kidneys and eyes) during embryonic development, causing signs and symptoms of the syndrome. About half of those affected with renal coloboma syndrome have identified a mutation in the PAX2 gene. In these cases, the cause of the disturbance is unknown. Alterations in gene expression of PAX2 are associated with certain cancers. It is believed that these changes increase the gene 's ability to protect cells from cell death, allowing tumor growth.

This condition is inherited as an autosomal dominant, which means a copy of the altered gene in each cell it is sufficient to cause the disorder. In some cases, an affected person inherits the mutation from an affected parent. Other cases result from new mutations in the gene and occur in people with no history of disease in your family  

Tests in IVAMI: in IVAMI perform detection of mutations associated with renal coloboma syndrome, by complete PCR amplification of the exons of the PAX2 gene, and subsequent sequencing.

Samples recommended: EDTA blood collected for separation of blood leukocytes, or impregnated sample card with dried blood (IVAMI may mail the card to deposit the blood sample).