What are common mistakes students make with sex linkage?
Sex linked disorders are genetic. I am assuming that is what you are asking about by using the term 'sex linkage'.
They are due to mutations on the sex chromosomes. To be clear, they are NOT due to an abnormal number (too many or too few) chromosomes. If that were true, one would then be dealing with chromosomal disorders.
Sex linked disorders in humans occur on the X chromosome, primarily. The Y chromosome plays little, if any, role at all in sex linked disorders. Why?
The Y chromosomes primarily codes for 'maleness'. This includes things like testosterone production. An SRY gene is one example of a gene only located on the Y chromosome.
Most sex-linked disorders occur on the X chromosome, since it carries many, many more genes on it.
And, finally, keep in mind that BOTH men and women carry at least one X chromosome.
Two examples of sex linked disorders: Duchenne muscular dystrophy and hemophilia.