Final answer:
Parents can expect a child with Down's syndrome to have developmental problems due to trisomy 21, an extra copy of chromosome 21 leading to aneuploidy. It is linked to intellectual disability, congenital health issues, and characteristic physical features, with a greater incidence in children born to women over 36.
Step-by-step explanation:
The parents of a new baby with Down's syndrome can expect developmental problems brought on by the pathologic interaction of 3 chromosomes where there should be only two. This condition is known as trisomy 21, which involves having an extra copy of chromosome 21, resulting in a total of three. It is the most common form of trisomy, and it leads to a range of developmental and intellectual disabilities. Down's syndrome is not a sex-linked monosomy like Turner syndrome, nor is it caused by defective mitochondrial protein synthesis or a single-gene disorder. Indeed, Down's syndrome is characterized by a phenotype of various degrees of intellectual disability, specific facial features, and potential physical and health issues such as congenital heart defects and vision problems. Contrary to a deficiency, it is a type of aneuploidy, specifically pertaining to chromosome 21.
Down's syndrome is the only autosomal trisomy in which affected individuals often survive into adulthood. The incidence of Down's syndrome is correlated with maternal age, with a higher likelihood of having a child with Down's syndrome in women over the age of 36. However, parents who do not have Down's syndrome can still have a child with the condition due to chromosomal nondisjunction during meiosis, the process that creates eggs and sperm. The risk associated with paternal age is significantly lower, as nondisjunction events are less common in sperm production.