Snyder-Robinson syndrome ... (Snyder-Robinson syndrome) - SMS Gen            

Syndrome Snyder-Robinson is a process characterized by mental retardation, musculoskeletal anomalies, and other developmental problems. This syndrome occurs exclusively in males.

Men with Snyder-Robinson syndrome exhibit a delayed development and intellectual disability from early childhood, which can vary from mild to profound. Often, language develops later and frequent difficulties. Some people affected never develop any discourse. Males most affected are thin and have reduced muscle mass. Weakness or hypotonia usually becomes evident in children, and muscle tissue loss continues to age. Often, those affected have difficulty walking and most have an unsteady gait.

Syndrome Snyder-Robinson leads to skeletal problems, especially osteoporosis, which begins in early childhood. Osteoporosis makes bones fragile and prone to fracture, particularly in the arms and legs. Most affected individuals also develop scoliosis, kyphosis, or both. Affected individuals tend to be lower than their peers and other members of his family. In addition, this syndrome is associated with characteristic facial features, including a prominent lower lip, cleft palate and facial asymmetry. Other additional signs and symptoms may include seizures that begin in childhood , and abnormalities of the genitals and kidneys.

This process is due to mutations in the SMS (spermine synthase) gene, located on the short arm of chromosome X (Xp22.1), spermine synthase encoding the enzyme. This enzyme is involved in the production of spermine, a small molecule polyamine call. Specifically, the enzyme reaction takes place that creates spermine from a related polyamine, spermidine. Polyamines have many critical functions within cells. Studies suggest that these molecules play a role in growth and cell division, synthesis of new proteins, the repair of damaged tissues and the control of apoptosis. Polyamines also appear to be necessary for normal development of the brain and other parts of the body.

They have been described at least five mutations responsible SMS Snyder-Robinson syndrome gene. Most of the identified mutations change an amino acid in spermine synthase enzyme. All known mutations greatly reduce or eliminate the activity of spermine synthase, which decreases the amount of spermine in the cell. This polyamine deficiency affects the normal development, including the development of the brain, muscles and bones, but do not know how these mutations give rise to specific signs and symptoms of Snyder-Robinson syndrome.

This process is inherited as a recessive X - linked pattern in males, who have only one X chromosome, an altered copy of the gene in each cell it is sufficient to express the disease. In females, having two X chromosomes, a mutation would have to occur in both copies of the gene to express syndrome. No cases have been reported of Snyder-Robinson syndrome in women.

Tests in IVAMI: in IVAMI perform detection of mutations associated with Snyder-Robinson syndrome, by complete PCR amplification of exons SMS 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).