Galactosemia Name: Olivia Taylor, Julia D, and Varsha M. Date: January 28, 2010 Period: 3

Summary of Galactosemia Is an inherited disease that makes the host unable to metabolize galactose. Galactose- is a simple sugar, found in ½ of milk. People with Galactosemia either don’t have, or lack the enzyme (GALT) that helps break down galactose. Infants that inherit Galactosemia who are feed dairy/milk products will have jaundice, vomiting, lethargy, and also mental retardation, cirrhosis, and kidney failure can occur. Did You Know Children with Galactosemia have lower (IQ) levels then their siblings, and that most girls with it, can’t conceive naturally. Though boys have normal testicular function.

.Galactosemia gene is located on the chromosome 9.

Mode of Inheritance 1.How do you get this disorder? – Autosomal recessive pattern – To get this disorder, a child must get one defective gene from each parent – If the child inherits one normal & one bad gene, they are okay. But can still pass the bad one to their kids. This gives their child another possibility of having Galactosemia. 2.What’s an Autosomal Recessive? – Is when a child has to get a copy of a gene from each parent to have that trait 3.What’s an Autosomal Dominant? – Is when a child has to only get one defected gene from one parent to inherit a disease 4.What’s Sex linked/X-linked? Is when a gene gets carried on a sex chromosome, especially an x-chromosome  XX- Female  XY-Male  Determines sex & sex characteristics

What are Alleles Alleles are represented by a small letter on the punnett square. -Capital letters are dominant, and lower case letters are recessive. Alleles are a way to identify in a gene pair, which gene produces what phenotypes. You get them from your parents Depending on the disease a small letter (Alleles) can be good or bad genes. In our disease it is bad. Example: In order to have Galactosemia you need two bad genes, or two small Alleles, or recessive(aa) genes. Having two of the same genes (aa) is called a homozygous pair. To be a carrier you need a dominant and a recessive gene (Aa), having a bad and a good genes is called a Heterozygous pairs.

Punnett squares to show the possibility of each child receiving the galactosemia gene gg= homozygous recessive (has the complete galactosemia gene) GG= homozygous dominant (does not have the gene at all) Gg= heterozygous dominant (Has a carrier of the gene but it does not show) Remember each punnett square is the possibility for EACH child to get the galactosemia gene! The Father is on the top of the punett square and the mother is on the left of the punnett square. GG g Gg g Gg G GG Gg g gg Father MOTHErMOTHEr MOTHERMOTHER

Punnett Square to explain probability with Ratios, and Percentages. Ratios- 1gg 1GG 2Gg Homozygous recessive Homozygous dominant Heterozygous dominan t If you add them up they should = 4 because there are only 4 possibilities Percentages- Homozygous recessive Homozygous dominant Heterozygous dominant 25% 25% 50% gg GG Gg All the percentages added must equal 100%, because there are four boxes each representing 25%

What each letter represents G is the dominant allele g is the recessive allele Phenotype is what we would see GG = No Galactosemia gene Gg = No Galactosemia gene but with a carrier gg = Galactosemia gene Genotype is what is in our genes GG is Homozygous dominant (no Galactosemia gene) Gg is Heterozygous dominant (Galactosemia gene) gg is homozygous recessive (Galactosemia gene) Gg gGggg gGggg GG gGg g Father MotherMother MotherMother Here we use the punnett squares to show what we can see and what is in our genes

Using Punnet Square Gg gGggg gGggg Mo t he r Father

Student Practice Punnett Square Practice GGGg gg Genotype: Ratio: Percentage: Phenotype: Ratio: ¼ Percentage: 25% G g G g

Lastly, a 3 generation hypothetical pedigree Autosomal Dominant Circle: Female Square: Male All White: Person has two healthy genes ½ Orange, ½ white: Person is a carrier, has one good gene and one bad gene All Orange: Person has the disease, has two bad genes Autosomal recessive All Orange :Person has two bad genes, is infected. All white: Person may be a carrier of disorder, but is fine. X-Linked Glactosemia male All orange square: gene is bad on X chromsome, Normal male All white square: gene is good on X chromsome. Glactosemia female All orange circle: gene is bad on X chromsome Carrier Glactosemia Female ½ orange, ½ white: Carrier of Glactosemia, bad gene on X, or Y. Is fine, but is a carrier, meaining having a good and bad gene.

Student Practice Circle: Female Square: Male All White: Person has two healthy genes ½ Orange, ½ white: Person is a carrier, has one good gene and one bad gene All Orange: Person has the disease, has two bad genes