Question

Which of the following is the chromosomal basis of Down syndrome as detected by amniocentesis?

विकल्प

• Extra chromosome 18 (47 chromosomes total)

• Extra chromosome 21 (47 chromosomes total)

• Missing X chromosome (45, X)

• Missing chromosome 21 (45 chromosomes total)

Answer 1

Down syndrome, also known as Trisomy 21, is caused by the presence of an extra chromosome 21, resulting in 47 chromosomes instead of the normal 46. This chromosomal abnormality is reliably detected through karyotyping of cultured fetal cells obtained via amniocentesis.