Peter plus syndrome (Peters plus syndrome) - Gen B3GALTL.

Peter plus syndrome is an inherited disease characterized by ocular abnormalities, short stature, cleft lip, with or without cleft palate, characteristic facial features and mental retardation.

Eye problems plus Peter syndrome appear in the anterior segment, which results in a cloudy cornea that causes blurred vision. The disease may also be associated with cataracts or other lens anomalies. Signs and symptoms of the disease are usually bilateral. The severity of corneal opacity and other eye problems may vary between individuals affected. Another common feature is the low height which is clear before birth. The height of adult males with this disorder varies from 141 centimeters to 155 centimeters and height of adult women varies from 128 centimeters to 151 centimeters. In addition, people affected with the syndrome have rhizomelia and brachydactyly. The characteristic facial features of the disease include a prominent forehead, small misshapen ears, small eyes, philtrum and Cupid 's bow. Cleft lip, with or without cleft palate, is present in about half the people with this disease. In most children, developmental milestones, such as walking and talking, are delayed more. Most affected individuals also have intellectual disability that can range from mild to severe, although some have normal intelligence. The severity of the physical traits does not predict the level of intellectual disability. Other signs and Less common symptoms include heart defects, structural brain abnormalities, hearing loss and kidney or genital abnormalities.

This process is due to mutations in the gene B3GALTL, located on the long arm of chromosome 13 (13q12.3). This gene encodes an enzyme called beta-1,3-glucosyltransferase (B3Glc-T), which participates in glycosylation process. Glycosylation modifies proteins so they can make a greater variety of functions. The B3Glc-T enzyme is involved in glycosylation pathway two step results in the formation of a structure of carbohydrates, fucose and glucose compounds in a specific location of several different proteins. The B3Glc-T enzyme is responsible for the second stage, adding a glucose molecule fucose molecule already bound to the protein. The B3GALTL gene is normally active in most body cells, suggesting that the enzyme-T B3Glc plays an important role in many cell types.

They have identified at least 10 mutations in the gene that cause B3GALTL Peter plus syndrome. Most gene mutations cause an abnormally short, nonfunctional version B3Glc-T enzyme that alters glycosylation. It is unclear how B3Glc-T loss of functional enzyme leads to the signs and symptoms of the syndrome, but with problems glycosylation is likely that the function of many proteins that can contribute to the variety of characteristics of the disease is interrupted. The most common mutation B3GALTL gene replaces a guanine nucleotide by one adenine near a gene called exon 8. This mutation alters the genetic information to synthesize B3Glc-T enzyme. As a consequence the resulting enzyme is abnormally short, nonfunctional.

Peter plus syndrome is inherited in an autosomal recessive pattern, which means that both copies of the gene in every cell must have mutations for alteration is expressed. The parents of an individual with an autosomal recessive disease have a copy of the mutated gene, but usually show no signs and symptoms of the disease.  

Tests in IVAMI: in IVAMI perform detection of mutations associated with Peter plus syndrome, by complete PCR amplification of exons B3GALTL 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).