Huntington disease is a fatal nervous system disorder causing degeneration of the brain.  It is caused by a defective gene on chromosome #4.  This is an autosomal dominant trait affecting 1 in 20,000 people. However, it is a delayed action gene that is not expressed until the affected individualis in his or her late 30s or40s.  The homosygous condition is lethal to the fetus.  Using the Hardy-Weinberg equation, determine (1) the frequency of carriers in the population, (2) the frequency of fetuses affected by the lethal homozygosity, and (3) the frequency of unaffected individuals.