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DiGeorge syndrome is also known as 22q11.2 deletion syndrome,DiGeorge anomaly, velocardiofacial syndrome (VCFS), Shprintzen syndrome, conotruncal anomaly face syndrome (CTAF) or Takao syndrome, Sedlackova syndrome, Cayler cardiofacial syndrome,〔(【引用サイトリンク】url=http://ghr.nlm.nih.gov/condition/22q112-deletion-syndrome )〕 Strong syndrome, congenital thymic aplasia, and thymic hypoplasia. This syndrome is caused by the deletion of a small piece of chromosome 22. As such, it is recommended that the name "22q11.2 deletion syndrome (22q11.2DS)" be used. 22q11.2DS is the most common microdeletion syndrome characterized by low copy repeats and the deletion occurs near the middle of the chromosome at a location designated ''22q11.2''—signifying its location on the long arm of one of the pair of chromosomes 22, on region 1, band 1, sub-band 2. The inheritance pattern is autosomal dominant and it has a prevalence estimated at 1:4000. The syndrome was described in 1968 by the pediatric endocrinologist Angelo DiGeorge.〔DiGeorge AM. Congenital absence of the thymus and its immunologic consequences: concurrence with congenital hypoparathyroidism. IV(1). White Plains, NY: March of Dimes-Birth Defects Foundation; 1968:116-21〕 22q11 deletion is also associated with truncus arteriosus and tetralogy of Fallot. ==Signs and symptoms== The features of this syndrome vary widely, even among members of the same family, and affect many parts of the body. Characteristic signs and symptoms may include birth defects such as congenital heart disease, defects in the palate, most commonly related to neuromuscular problems with closure (velopharyngeal insufficiency), learning disabilities, mild differences in facial features, and recurrent infections. Infections are common in children due to problems with the immune system's T-cell-mediated response that in some patients is due to an absent or hypoplastic thymus. 22q11.2 deletion syndrome may be first spotted when an affected newborn has heart defects or convulsions from hypocalcemia due to malfunctioning parathyroid glands and low levels of parathyroid hormone (parathormone). Affected individuals may also have other kinds of birth defect including kidney abnormalities and significant feeding difficulties as babies. Gastrointestinal issues are also very common in this patient population. Digestive motility issues may result in constipation. Disorders such as hypothyroidism and hypoparathyroidism or thrombocytopenia (low platelet levels), and psychiatric illnesses are common late-occurring features. Microdeletions in chromosomal region 22q11.2 are associated with a 20 to 30-fold increased risk of schizophrenia.〔 〕 Studies provide various rates of 22q11.2 deletion syndrome in schizophrenia, ranging from 0.5 to 2.0% and averaging about 1.0%, compared with the overall estimated 0.025% risk of the 22q11.2 deletion syndrome in the general population.〔 〕 Salient features can be summarized using the mnemonic CATCH-22 to describe DiGeorge syndrome, with the 22 to remind one the chromosomal abnormality is found on the 22 chromosome, as below: Cardiac abnormality (especially tetralogy of Fallot) Abnormal facies Thymic aplasia Cleft palate Hypocalcemia/Hypoparathyroidism Individuals with a 22q11.2 deletion can have many possible features, ranging in number of associated features and from the mild to the very serious. Symptoms shown to be common include: * Congenital heart disease (40% of individuals), particularly conotruncal malformations (tetralogy of Fallot, interrupted aortic arch, ventricular septal defect, and persistent truncus arteriosus) * Cyanosis (bluish skin due to poor circulation of oxygen-rich blood) * Palatal abnormalities (50%), particularly velopharyngeal incompetence, submucosal cleft palate, and cleft palate; characteristic facial features (present in the majority of Caucasian individuals) including hypertelorism * Learning difficulties (90%), including cognitive deficits, attention deficit disorders * Hypocalcemia (50%)(due to hypoparathyroidism) * Significant feeding problems (30%) * Renal anomalies (37%) * Hearing loss (both conductive and sensorineural) (hearing loss with craniofacial syndromes) * Laryngotracheoesophageal anomalies * Growth hormone deficiency * Autoimmune disorders * Immune disorders due to reduced T cell numbers * Seizures (with or without hypocalcemia) * Skeletal abnormalities * Psychiatric disorders〔 This syndrome is characterized by incomplete penetrance and therefore there is a marked variability in clinical expression between the different patients. This often makes early diagnosis difficult.〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「DiGeorge syndrome」の詳細全文を読む スポンサード リンク
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