Dapo Adegbile Nevin Varghese Victor Veras 1-28-10 Period 2

Summary of Polydactyly Polydactyly is a condition in which a person has more than five fingers per hand or five toes per foot. Polydactyly occurs in the womb; instead of developing only one thumb and four fingers an extra finger is added Usually the hand is formed in the womb and when it is being split it is made into 4 fingers, 1 thumb. However sometimes an extra split occurs and abnormal number of fingers is produced It is a autosomal dominate characteristic

Chromosome Disorder is Located on The cause of the disorder is usually found on chromosome 13. However for some cases it is not known There is another gene or chromosome that the mutation could happen in that could cause polydactyly

Mode of Inheritance Polydactyly is autosomal dominant. Autosomal dominant means that an offspring can get this disease by having it passed down from just one parent. Polydactyly occurs because of genetic disorders or errors in fetal development. Polydactyly can also be a symptom for another disease. Ex. – Bardet-Biedl syndrome Ex. – Bloom’s syndrome Ex. – Jeune’s thoracic dystrophy syndrome

What are Alleles? A person has two alleles per gene You get one of the two alleles in a gene from your father and the other from your mother Recessive alleles are represented by the letter of the characteristic in lower-case form Dominant alleles are represented by the letter of the characteristic in capital R – Dominant r – Recessive The dominant alleles and the recessive alleles both represent two different possible characteristics. The “characteristic” will be dominant if the gene has one dominant allele or two dominant alleles The “characteristic” will be recessive if the gene has two recessive genes only

Punnent Square – Demonstration G g w w h h G g GG Gr gg Ww hh W h Heterozygous Homozygous

Probabiliy of Disease occuring G g Ratio 1GG 2Gg 1gg G g GG Gg gg Percentage 25% -GG 50% - Gg 25% - gg 75% chance of getting Polydactyly 25% chance of not getting Polydactyly

What the letters mean GG – two dominant alleles Gg – one dominant allele and one recessive allele gg – two recessive alleles G g GG Gg gg Phenotype GG = Recieve polydactyly Gg = Receive polydactyly gg = Normal amount of fingers Top – Father Left – Mother Genotype GG = Homozygous dominant Gg = Heterozygous dominant gg = Homozygous recessive

Genotype and Phenotype possibility G g G g GG Gg gg Phenotype - Ratios- 3 for polydactyly : 1 for normal - Percentage – 75% chance of polydactyly 25% chance of normal # of f fingers Genotype - Ratios- 1 GG : 2 Gg : 1 gg - Percentages- 25% GG : 50% Gg : 25%gg

Student Practice Phenotypes Genotypes G G G Ratio – Percentage – g

3 Generation Hypothetical Pedigree – Autosomal Dominant Female – circle Male – Square All green – homozygous recessive gene, person doesn’t have the disease, person has 2 healthy alleles Half green, half black – heterozygous gene, person has the disease because you only one dominant gene with the disease to get it

Student Practice Key – circle – female square – male shaded in – two dominant alleles not shaded – two recessive alleles half shaded – one dominant and one recessive allele