CHROMOSOMAL DISORDERS IN HUMAN
SYNDROME
The word syndrome means ‘disorder‘.Several body character appears as a disease due to chromosomal abnormalities.This is known as syndrome.These are of various kinds.Some of them are discussed below:
1.Down syndrome: It was described by John Langdon Down, the British doctor, described the syndrome in 1866.It is caused by the presence of all or part of a third copy of chromosome 21.It is caused due to trisomy of 21st pair.Such persons have 47 chromosomes.This disease is also known as MONGOLIAN IDIOCY. It can be identified during pregnancy by prenatal screening.Down syndrome is one of the most common chromosome abnormalities in humans.It occurs in one out of 700 -800 live births. Down syndrome causes birth defects, medical problems, and some degree of intellectual disability.These patients have broad forehead,short neck,fingers are stubby,flat nose and abnormal outer ears.There face is moon like.Eyes are widely separated.They have flattened nose and mouth is permanently opened and a long protruding tongue.Patients are mentally retarded.They mostly die at the age of 16.It has no cure.
2.Klinefelter syndrome: It was named by Harry Klinefelter. It is also known as 47,XY XXY or X. It is due to the presence of two or more X chromosomes in males.They are trisomic for 23rd pair.They have an extra X chromosome.It occurs in 1:500 to 1:1000 live male births.It occurs randomly. It can be recognized by a genetic test which is also known as karyotype. They are sterile males but they have under developed secondary sexual character of males.They have poorly developed testis.They are mentally retarded.They develop breast like females.This is known as gynecomastia. It has no cure.
3.Turner syndrome: It was described by Henry Turner.In this kind of syndrome,female are without sometimes may not have enough X chromosome.These are monosomic for 23rd pair.These are sterile females. They have poorly developed ovaries.They have flat breast.There kidneys are poorly developed.They do not possess menstrual cycle.It is believed that out of every 2000 birth one is turner’s syndrome.It has no cure.
