The DNA of an individual carries their genetic information. This information is contained in the nucleus, coiled to make chromosomes – 23 pairs in total. Each chromosome codes for a specific trait, and contains genes – the code for proteins. Chromosomes consist of two sister chromatids joint by a centromere, with the regions above the centromere called the ‘p’ arms and the region below called the ‘q’ arms (see figure 1). 22q11 deletion syndrome (22q11DS) refers to the deletion of a section of the q arm of the 22nd chromosome at position 11. (NHS, 2015) Patients often have different numbers of genes missing from this locus but there has been no identified relationship between number of genes missing and the symptoms presented. Figure 1 http://ghr.nlm.nih.gov/handbook/basics/chromosome
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Symptoms of the disorder can include learning difficulties, feeding problems and/or an abnormal appearance (such as an irregular shaped skull). (NHS, 2015) Sufferers are prone to opportunistic infections due to uncharacteristic development of the thymus gland during pregnancy, whereby it could be smaller than average, in an altogether incorrect location or simply be absent. This means there will be significantly less t cells in the body resulting in an impaired immune system. (Max Appeal, 2015) 75% of sufferers of this disorder are found to have some sort of heart defect, with one particular study finding that 43 of 46 deaths in new-borns –with this disorder – were due to heart problems. (Ryan, 1997) Due to the variable symptoms of this chromosome deletion, patients of the same genetic mutation were often diagnosed with different disorders such as DiGeorge syndrome, velocardiofacial syndrome (VCFS), conotruncal anomaly face syndrome, and Cayler cardiofacial syndrome. (Genetics Home Reference,
Symptoms of the disorder can include learning difficulties, feeding problems and/or an abnormal appearance (such as an irregular shaped skull). (NHS, 2015) Sufferers are prone to opportunistic infections due to uncharacteristic development of the thymus gland during pregnancy, whereby it could be smaller than average, in an altogether incorrect location or simply be absent. This means there will be significantly less t cells in the body resulting in an impaired immune system. (Max Appeal, 2015) 75% of sufferers of this disorder are found to have some sort of heart defect, with one particular study finding that 43 of 46 deaths in new-borns –with this disorder – were due to heart problems. (Ryan, 1997) Due to the variable symptoms of this chromosome deletion, patients of the same genetic mutation were often diagnosed with different disorders such as DiGeorge syndrome, velocardiofacial syndrome (VCFS), conotruncal anomaly face syndrome, and Cayler cardiofacial syndrome. (Genetics Home Reference,