TAR Syndrome and Rare Disorders
TAR Syndrome and Rare Disorders
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TAR Syndrome- Thrombocytopenia Absent Radius
TAR syndrome is caused by two separate mutations of the RBM8A gene and is characterized by the absence of the radial bone in each forearm, shorter stature, additional missing bones and joints, and thrombocytopenia. Thrombocytopenia appears first in infancy but usually becomes less severe or returns to close to normal over several years. Infants and young children are particularly vulnerable to episodes of severe bleeding which may occur in the brain and other organs. Children who survive this period and do not have damaging bleeding in the brain usually have a normal life expectancy and normal intellectual development. Other signs and symptoms vary and include heart defects, kidney defects, and other skeletal differences. Roughly 49% of people with TAR syndrome also have difficulty digesting cow’s milk. TAR syndrome is inherited as an autosomal recessive genetic disorder and caused by deletion and/or mutations in the RBM8A gene.
Fanconi anemia is a condition that affects many parts of the body. People with this condition may have bone marrow failure, physical abnormalities, organ defects, and an increased risk of certain cancers.
The major function of bone marrow is to produce new blood cells. These include red blood cells, which carry oxygen to the body’s tissues; white blood cells, which fight infections; and platelets, which are necessary for normal blood clotting. Approximately 90 percent of people with Fanconi anemia have impaired bone marrow function that leads to a decrease in the production of all blood cells. Affected individuals experience extreme tiredness (fatigue) due to low numbers of red blood cells, frequent infections due to low numbers of white blood cells (neutropenia), and clotting problems due to low numbers of platelets (thrombocytopenia). People with Fanconi anemia may also develop myelodysplastic syndrome, a condition in which immature blood cells fail to develop normally.
More than half of people with Fanconi anemia have physical abnormalities. These abnormalities can involve irregular skin coloring such as unusually light-colored skin (hypopigmentation) or flat patches on the skin that are darker than the surrounding area. Other possible symptoms of Fanconi anemia include malformed thumbs or forearms and other skeletal problems including short stature; malformed or absent kidneys and other defects. Gastrointestinal abnormalities; heart defects; eye abnormalities such as small or abnormally shaped eyes; and malformed ears and hearing loss.
PFFD- Proximal Femoral focal deficiency
Proximal femoral Focal deficiency (PFFD) refers to a spectrum of congenital (present at birth) malformations of the thigh bone (femur) due to incomplete or abnormal development. It may affect one leg (most commonly) or both legs. Severity can range from minor shortening of the femur (appearing normal), to complete absence of much or all of the femur. Deficiency or instability of the hip and knee joint often are also present and effect treatment options for each person. Various systems for classifying PFFD have been proposed. Some experts classify according to radiological appearance, while others classify according to factors that affect options for treatment.
Holt-Oram syndrome affects the bones of the hands and arms and possibly also affect the heart. The syndrome causes at least one bone in the wrist to not form normally. Other bones in the hands, arms, and shoulder may also have developed abnormally. Many of these developmental changes in the bones can only be seen on an x-ray. Most people with Holt-Oram syndrome also have heart problems, including problems due to the way the heart formed (congenital) or problems with the way the heart beats.
Holt-Oram syndrome is caused by genetic changes in the TBX5 gene. The syndrome is inherited in an autosomal dominant manner. An x-ray of the hands, wrists, and arms, echocardiogram of the heart, and genetic testing are used to confirm the diagnosis.
Roberts syndrome is a genetic disorder characterized by limb and facial abnormalities. Affected individuals are born with abnormalities of all four limbs and typically have shortened arm and leg bones. They may also have phocomelia (in severe cases); abnormal or missing fingers and toes; joint deformities and numerous facial abnormalities including cleft lip and or cleft palate, ear abnormalities, small nostrils and a beaked nose. Microcephaly, intellectual disability, and heart, kidney or genital abnormalities may also be present. Infants with a severe form of Roberts syndrome are often stillborn or die shortly after birth, while mildly affected individuals may live into adulthood. It is caused by mutations in the ESCO2 gene and is inherited in an autosomal recessive pattern