What is Down’s syndrome ? Give its symptoms and cause. Why is it that the chances of having a child with Down’s syndrome increases if the age of the mother exceeds forty years ?
What is Down’s syndrome ? Give its symptoms and cause. Why is it that the chances of having a child with Down’s syndrome increases if the age of the mother exceeds forty years ?
Down's syndrome is a human genetic disorder caused due to trisomy of chromosome no. $21$ . Such individuals are aneuploid and have $47$ chromosomes $(2 \mathrm{n}+1)$. The symptoms include mental retardation, growth abnormalities, constantly open mouth, dwarfness etc. The reason for the disorder is the non-disjunction (failure to separate) of homologous chromosome of pair $21$ during meiotic division in the ovum. The chances of having a child with Down's syndrome increase with the age of the mother $(+40)$ because ova are present in females. Since their birth and therefore older cells are more prone to chromosomal non-disjunction because of various physico-chemical exposures during the mother's life-time.
Similar Questions
In which disorder $XXY$ karyotype is present ?
In which disorder $XXY$ karyotype is present ?
Match the following:
Column – I
Column $- II$
$(1)$ Failure of cytokinesis
$(p)$ To study in beritance of particular traits
$(2)$ Trisomy of 21
$(q)$ Polyploidy
$(3)$ Error of metabolism
$(r)$ Down's syndrome
$(4)$ Pedigree analysis
$(s)$ Phenylketonuria
Match the following:
| Column – I | Column $- II$ |
| $(1)$ Failure of cytokinesis | $(p)$ To study in beritance of particular traits |
| $(2)$ Trisomy of 21 | $(q)$ Polyploidy |
| $(3)$ Error of metabolism | $(r)$ Down's syndrome |
| $(4)$ Pedigree analysis | $(s)$ Phenylketonuria |
Down’s syndrome is caused by an extra copy of chromosome number $21$. What percentage of offspring produced by an affected mother and a normal father would be affected by this disorder
Down’s syndrome is caused by an extra copy of chromosome number $21$. What percentage of offspring produced by an affected mother and a normal father would be affected by this disorder
- [AIPMT 2003]
Identify the disease on basis of following characters.
$(1)$ Short statured with small round head.
$(2)$ Furrowed tongue and partially open month.
$(3)$ Palm is broad with characteristic palm crease.
Identify the disease on basis of following characters.
$(1)$ Short statured with small round head.
$(2)$ Furrowed tongue and partially open month.
$(3)$ Palm is broad with characteristic palm crease.
In man, which of the following genotypes and phenotypes may be the correct result of aneuploidy in sex chromosomes
In man, which of the following genotypes and phenotypes may be the correct result of aneuploidy in sex chromosomes