TBX1 Gene

22q11.2 deletion syndrome (which is also known by several other names, listed below) is a disorder caused by the deletion of a small piece of chromosome 22. The deletion occurs near the middle of the chromosome at a location designated q11.2.

22q11.2 deletion syndrome has many possible signs and symptoms that can affect almost any part of the body. The features of this syndrome vary widely, even among affected members of the same family. People with 22q11.2 deletion syndrome commonly have heart abnormalities that are often present from birth, recurrent infections caused by problems with the immune system, and distinctive facial features. In affected individuals, the muscles that form the roof of the mouth (palate) may not close completely, even though the tissue covering them does, resulting in a condition called submucosal cleft palate. The abnormal palate is often highly arched and there may be a split in the soft flap of tissue that hangs from the back of the mouth (bifid uvula). Submucosal cleft palate can also interfere with normal speech by causing air to come out of the nose during speech, leading to nasal-sounding speech. Affected individuals may also have breathing problems, kidney abnormalities, low levels of calcium in the blood (which can result in seizures), a decrease in blood platelets (thrombocytopenia), significant feeding difficulties, gastrointestinal problems, and hearing loss. Skeletal differences are possible, including mild short stature and, less frequently, abnormalities of the spinal bones.

Many children with 22q11.2 deletion syndrome have developmental delays, including delayed growth and speech development, and some have mild intellectual disability or learning disabilities. Older affected individuals have difficulty reading, performing tasks involving math, and problem solving. Children with this condition often need help changing and adapting their behaviors when responding to situations. Additionally, affected children are more likely than children without 22q11.2 deletion syndrome to have attention-deficit/hyperactivity disorder (ADHD) and developmental conditions such as autism spectrum disorder that affect communication and social interaction.

Because the signs and symptoms of 22q11.2 deletion syndrome are so varied, different groupings of features were once described as separate conditions. Doctors named these conditions DiGeorge syndrome, velocardiofacial syndrome (also called Shprintzen syndrome), and conotruncal anomaly face syndrome. In addition, some children with the 22q11.2 deletion were diagnosed with the autosomal dominant form of Opitz G/BBB syndrome and Cayler cardiofacial syndrome. Once the genetic basis for these disorders was identified, doctors determined that they were all part of a single syndrome with many possible signs and symptoms. To avoid confusion, this condition is usually called 22q11.2 deletion syndrome, a description based on its underlying genetic cause.

22q11.2 deletion syndrome (which is also known by several other names, listed below) is a disorder caused by the deletion of a small piece of chromosome 22. The deletion occurs near the middle of the chromosome at a location designated q11.2.

22q11.2 deletion syndrome has many possible signs and symptoms that can affect almost any part of the body. The features of this syndrome vary widely, even among affected members of the same family. People with 22q11.2 deletion syndrome commonly have heart abnormalities that are often present from birth, recurrent infections caused by problems with the immune system, and distinctive facial features. In affected individuals, the muscles that form the roof of the mouth (palate) may not close completely, even though the tissue covering them does, resulting in a condition called submucosal cleft palate. The abnormal palate is often highly arched and there may be a split in the soft flap of tissue that hangs from the back of the mouth (bifid uvula). Submucosal cleft palate can also interfere with normal speech by causing air to come out of the nose during speech, leading to nasal-sounding speech. Affected individuals may also have breathing problems, kidney abnormalities, low levels of calcium in the blood (which can result in seizures), a decrease in blood platelets (thrombocytopenia), significant feeding difficulties, gastrointestinal problems, and hearing loss. Skeletal differences are possible, including mild short stature and, less frequently, abnormalities of the spinal bones.

Many children with 22q11.2 deletion syndrome have developmental delays, including delayed growth and speech development, and some have mild intellectual disability or learning disabilities. Older affected individuals have difficulty reading, performing tasks involving math, and problem solving. Children with this condition often need help changing and adapting their behaviors when responding to situations. Additionally, affected children are more likely than children without 22q11.2 deletion syndrome to have attention-deficit/hyperactivity disorder (ADHD) and developmental conditions such as autism spectrum disorder that affect communication and social interaction.

Because the signs and symptoms of 22q11.2 deletion syndrome are so varied, different groupings of features were once described as separate conditions. Doctors named these conditions DiGeorge syndrome, velocardiofacial syndrome (also called Shprintzen syndrome), and conotruncal anomaly face syndrome. In addition, some children with the 22q11.2 deletion were diagnosed with the autosomal dominant form of Opitz G/BBB syndrome and Cayler cardiofacial syndrome. Once the genetic basis for these disorders was identified, doctors determined that they were all part of a single syndrome with many possible signs and symptoms. To avoid confusion, this condition is usually called 22q11.2 deletion syndrome, a description based on its underlying genetic cause.

Critical congenital heart disease (CCHD) is a term that refers to a group of serious heart defects that are present from birth. These abnormalities result from problems with the formation of one or more parts of the heart during the early stages of embryonic development. CCHD prevents the heart from pumping blood effectively or reduces the amount of oxygen in the blood. As a result, organs and tissues throughout the body do not receive enough oxygen, which can lead to organ damage and life-threatening complications. Individuals with CCHD usually require surgery soon after birth.

Although babies with CCHD may appear healthy for the first few hours or days of life, signs and symptoms soon become apparent. These can include an abnormal heart sound during a heartbeat (heart murmur), rapid breathing (tachypnea), low blood pressure (hypotension), low levels of oxygen in the blood (hypoxemia), and a blue or purple tint to the skin caused by a shortage of oxygen (cyanosis). If untreated, CCHD can lead to shock, coma, and death. However, most people with CCHD now survive past infancy due to improvements in early detection, diagnosis, and treatment.

Some people with treated CCHD have few related health problems later in life. However, long-term effects of CCHD can include delayed development and reduced stamina during exercise. Adults with these heart defects have an increased risk of abnormal heart rhythms, heart failure, sudden cardiac arrest, stroke, and premature death.

Each of the heart defects associated with CCHD affects the flow of blood into, out of, or through the heart. Some of the heart defects involve structures within the heart itself, such as the two lower chambers of the heart (the ventricles) or the valves that control blood flow through the heart. Others affect the structure of the large blood vessels leading into and out of the heart (including the aorta and pulmonary artery). Still others involve a combination of these structural abnormalities.

People with CCHD have one or more specific heart defects. The heart defects classified as CCHD include coarctation of the aorta, double-outlet right ventricle, D-transposition of the great arteries, Ebstein anomaly, hypoplastic left heart syndrome, interrupted aortic arch, pulmonary atresia with intact septum, single ventricle, total anomalous pulmonary venous connection, tetralogy of Fallot, tricuspid atresia, and truncus arteriosus.