Nicolaides-Baraitser syndrome ... (Nicolaides-Baraitser syndrome) - Gen SMARCA2.
Syndrome Nicolaides-Baraitser is a disorder that affects many body systems. Although affected individuals can have a wide variety of signs and symptoms, the most common include thinning hair on the scalp, microcephaly, characteristic facial features (triangular face, sunken eyes, a thin nasal bridge, broad nose, pointy nose, and lower lip thickness), short stature, prominent joints of the fingers, brachydactyly, epileptic episodes, and moderate to severe mental retardation with impaired language development. Other signs and symptoms may include deficiency subcutaneous fat from the face, pale skin, eczema, umbilical hernia or inguinal hernia, dental anomalies (widely spaced teeth, delayed teething and hypodontia. Moreover, most of affected males have cryptorchidism and women may have underdeveloped breasts. Nearly half of people with the syndrome Nicolaides-Baraitser has problems feeding.
The Nicolaides-Baraitser syndrome is due to mutations in the gene SMARCA2, located on the short arm of chromosome 9 (9p22.3). This gene encodes a subunit of a complex group of proteins known as the similar SWI / SNF complex. These complexes regulate gene expression through a process known as chromatin remodeling. The chromatin structure can be remodeled to alter the force with which the DNA is assembled. The chromatin remodeling is a form of regulated gene expression during development. To provide energy for chromatin remodeling, the SMARCA2 protein utilizes ATP molecule. The SWI / SNF complexes regulate genes that are involved in many processes, including DNA repair damaged DNA copying, as well as control of growth, division and cell differentiation. It is believed that SMARCA2 protein subunits and other SWI / SNF act as tumor suppressors.
They have identified at least 50 mutations in the gene responsible SMARCA2 Nicolaides-Baraitser syndrome. Almost all genetic mutation changes the amino acid protein. These mutations are located within an area of the protein which binds ATP and is responsible for providing energy to the SWI / SNF complex. While these altered proteins are capable of forming complex SWI / SNF, these complexes are not functional and can not participate in chromatin remodeling. Disruption of this regulation process alters the activity of many genes, which probably explains the various signs and symptoms of Nicolaides-Baraitser syndrome.
This disease is inherited as an autosomal dominant, which means that a copy of the altered gene in each cell is sufficient for the disease to be expressed. All cases of this disease are caused by new mutations in the gene that occur during the formation of reproductive cells or early embryonic development. These cases occur in people with no history of disease in your family
Tests in IVAMI: in IVAMI perform detection of mutations associated with Nicolaides-Baraitser syndrome by complete PCR amplification of exons SMARCA2 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).