1. Huntington Disease (HD) is an autosomal dominant, neurodegenerative disorder

Question

1. Huntington Disease (HD) is an autosomal dominant, neurodegenerative disorder caused by the expansion of a triplet sequence (CAG) repeated multiple times within the coding region of the huntingtin gene (the DNA sequence of this gene is known). A person's risk of developing HD and the age at which they will begin showing symptoms is strongly correlated with the number of tandem repeats they carry (<26 repeats = definitely won't get HD; >40 repeats = definitely will get HD). The following data were obtained for a family, where the father is known to have HD. How many different "H" alleles are there in this family and how many different "h" alleles? Would you expect either of the children to develop HD when they get older?

Explanation / Answer

HUNTING TON DISEASE IS A NEURO DEGENERATIVE DISEASE , PROGRESSIVE DISEASE THAT AFFECTS MUSCLE CORDINATION AND LEADS TO MENTAL DECLINE   AND BEHAVIOURAL CHANGES , THEY ARE VARIANT SUCH AS JUVINILE , AKINETIC RIGID , WESTPHAL VARIANTS. THE GENE PROVIDES THE INFORMATION FOR THE PROTEIN HUGTINGTIN , EXPANSION OF THE CAG REPEATING TO PRODUCE VARIOUS OTHER DIFFRENT TYPES OF PROTEINS , WHICH CAUSES THE DAMAGE TO THE BRAIN CELLS , IT IS AUTOSOMAL DOMINANT DISEASE ,

HERE IN THIS CASE THE DAD IS CARRYING THE DEFECTIVE COPY OF THE GENE , PRESYSMPTOMATIC TEST CAN BE DONE

How many different "H* alleles are there in this family?

THE H ALLELE IS NOT AFFECTED GENE IN THE FAMILY HENCE , THE ALLELE WILL BE Hh , FATHER IS AFFECTED SO THE ALLELS INCLUDE HH , TWO CHILDREN W ILL BE HAVING THE ALLELE Hh , 50 PERCENT OF THE ALLELS WILL BE AFFETED

How many different "h" alleles?

WHEN THERE hh ALLELE OF THE MOTHER IS NOT AFFECTED HENCE , IF BOTH THE PARENTS ARE HOMOZYGOUS , THERE WILL BE ZERO PERCENT CHANCES OF CARRYING THE DISEASE , HERE IN OUR CASE FATHER IS AFFECTED , SO THE UNAFFECTED ALLELE WILL BE ONLY 50 PERCENT CARRYS hh ALLELE

Would you expect either of the children to develop HD when they get older?

OUT OF 4 CHILDREN TWO WILL BE HAVING THE AFFECTED GENE , SO THE CARRY 50 PERCENT CHANCES OF HAVING THE DISEASE WHICH CAN INCRESE WITH THE AGE, THE INSATBLITY INCREASES WITH THE NUMBER OF CAG REPEATS

Related Questions

Navigate

• Browse (All)
• Browse 1
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.