Which disorder is caused by the loss of one $X$ chromosome in females?

$A$ female with $XXXX$ chromosomes will have the following number of Barr bodies:

Which of the following is an example of a non-Mendelian disorder?

In which of the genetic disorders does an individual have an overall masculine development,gynaecomastia,and is sterile?

Three copies of chromosome-$21$ in a child with Down's syndrome have been analysed using molecular biology technology to detect any possible $DNA$ polymorphism with reference to different alleles located on chromosome-$21$. Results showed that out of $3$ copies,$2$ of the chromosomes of the child contain the same alleles as one of the mother's alleles. Based on this,when did the non-disjunction event most likely occur?

What is the sex chromosome complement in a male child with Down syndrome?