Down Syndrome

Down syndrome in general is referred to as Trisomy 21 or Trisomy G. It is a disease caused by chromosomal disorder. This was identified by Scientist named John Langdon Down in the year 1866. The disorder in 21^st chromosome was discovered by Jerome Lejeune in the year 1959. It damages cognitive growth and physical growth of an individual, resulting changes in facial expression. It results in unusual expression, size and shape in eyes, face, limbs and toes. They are also integrated with infections in ear, thyroid, sleep apnea and congenital heart dysfunctions. Medical procedures like amniocentes, CVS (Chorionic villus sampling), genetic testing and percutaneous umbilical cord blood sampling helps in detection of Down syndrome presence in fetus during pregnancy period. IQ of an individual with Down syndrome is 50 instead of normal IQ 100. World Down Syndrome Day was celebrated first time on 21/03/2006. The date and month selection correlates with the disease occurrence i.e. 21 and trisomy stands for disease nomenclature.

 Genetics of Familial Down syndrome

Additional copy of genetic material occurs in 21^st chromosome. When entire copy is present it is referred as trisomy 21 and only part of this due to translations. Instead of 46 chromosomes, Down syndrome individual has 47 chromosomes. It is just because of meiotic nondisjunction. Each gamete has 24 chromosomes in place of normal 23 chromosomes. It is characterized by presence of three copies of 21^st chromosome. It is estimated 95% of the trisomy 21 is Down syndrome. About 88% is nondisjunction in the gametes of maternal and other 7% in gametes of paternal. The nondisjunction event of gametes is due to cell division of normal embryo trisomy 21 results in mosaic Down syndrome or mosaicism. Translocation of trisomy 21 may result in Robertsonian translocation. Translocation Down syndrome is often referred as familial Down syndrome.

Symptoms of Down syndrome

This may be a result of altered genetic mechanism. It is not possible by any means to predict that an infant is with Down syndrome before birth. They are characterized by presence of abnormal chin, fissures in eyes like mongoloid fold, muscle tone is worse, palmar fold, and tongue is very large especially near the tonsils also referred as macroglassia in medical terms. They usually have short neck, a brushfield spot that is some white spots on iris, more space between toes and dermatoglyphs. They are mentally retarded and sensitivity ranges from mild to moderate to severe.

They cannot speak continuously and not understood clearly. As a motor skill takes longer time it results in cognitive development impairing. Some can walk at around 2 years from birth and some may take 4 years to walk. Growth factor expression is slow and hence they are short.

Complications associated with Down syndrome

As the function of organs is hindered it may impair the heart during the time of birth. Some are apparent over the period of time resulting in epilepsy. It results in congenital heart disease like leukemia. Transient leukemia, acute lymphoblastic and megakaryoblastic leukemia occurs as a result of hematologic malignancy. They can cause impairing of thyroid gland. Congential hypothyroidism is usually prevalent in individuals with Down syndrome. Down syndrome increases the risk of severe constipation. Diseases like Hirschsprund’s disease, gastroesophageal reflux disease, celiac disease, annular pancreas and imperforate anus are commonly associated with Down syndrome. It leads to infertility of both males and females, premature birth of child and or complex labour. Risk of Alzheimer’s disease is more with trisomy individuals. Most of them have strabismus, glaucoma and refractive errors.

Management

Down syndrome is considered as genetic harm to infant birth. Individual parents with this syndrome should question themselves about their transmission of disease to infants. Plastic surgery can help in proper facial expression. Examination before the child birth helps in minimizing the health effects of infant. Proper diagnosis and treatment for the identified symptoms should be done at each developmental stage during pregnancy.