Galactosemia is a condition that affects how the body digests the sugar galactose. The most common form of galactosemia, type I, is the most severe, and it results from mutations within the GALT gene, which encodes for an enzyme that processes galactose. Galactosemia is inherited in an autosomal recessive pattern.Imagine that your friend Mary has normal metabolism, but that her brother John has galactosemia. Mary and John's parents, Patricia and Les, are unaffected, although their maternal grandmother, Jean, also had the condition.
If wild-type GALT is designated as G and the recessive allele is designated as g, determine the genotypes of the following individuals.
Drag a genotype to each individual in the pedigree. Labels may be used more than once or not at all.
Galactosemia is a human genetic disorder caused by a deficiency of the enzyme galactose-1-phosphate uridylyltransferase (commonly called GALT).
Children with galactosemia seem normal at birth, but begin to show symptoms as soon as they drink milk. This is because they cannot metabolize galactose, a simple sugar that results from the breakdown of lactose (the sugar found in milk).
Early symptoms of galactosemia include vomiting and diarrhea. If untreated, affected babies will develop enlarged livers, cataracts, and mental retardation. Depending on the alleles the baby has inherited, early death may result.
John and Jane Jones' newborn baby girl, Leah, has just been diagnosed with galactosemia. Prior to their genetic counseling appointment, they submitted this family history:
John and Jane's older child, a son named Lee, does not have galactosemia.
John is the only child of Hanna and Harry.
Harry was an only child. Hanna has two older sisters, Hope (the oldest) and Holly.
Both Harry and Hanna's parents lived in good health into their 80s.
Jane's brother, Joe, is married to Jen. They have a son, Les, who is a healthy nine-year-old with myopia (nearsightedness) but no sign of galactosemia.
Jane's mother, Hilda, is alive and healthy; Jane's father, Henry, passed away last year of a sudden heart attack. Hilda and Henry have no family history of galactosemia.
Use the information in the family history to construct a pedigree for this family.
Drag the correct symbols to their appropriate locations on the pedigree below. Not all symbols will be used.Hann
1st EditionKenneth R. Miller, Levine
15th EditionJohn David Jackson, Patricia Meglich, Robert Mathis, Sean Valentine
13th EditionDavid N. Shier, Jackie L. Butler, Ricki Lewis
7th EditionJulie S Snyder, Mariann M Harding