Pedigree Analysis

Pedigree: Analyzing the pattern of inheritance of a special trait throughout a family. And it shows the presence or absence of a trait with in the family across generation.

Genotype: Genetics that makeup an organism. (Example tt) Phenotype: physical appearance of characterization of an organism. (Example Tall). Dominant allele: Allele that phenotypically expresses over the another allele. Recessive allele: Allele that only phenotypically expresses in the absence of dominant allele. Autosomal trait: traits found in autosome chromosome. Sex-linked trait: traits found in sex chromosome (XY). Homozygous: containing the same alleles for a certain gene. (TT, tt) Heterozygous: containing different alleles for a certain gene. (Tt)

Pedigree symbols

Pedigree analysis helps to: Determining the genotype, Identifying phenotype and Predicting if a certain traits going to be inherited to the offspring Dominant gene: Affected individual have at least one affected parent. In general, Phenotype is seen in every generation. Recessive gene: Unaffected parent can have affected offspring.

Autosomal dominant allele The diagram displays the inheritance of dimples in a family. The allele for dimples (D) is dominant to the allele for no dimples (d). At the top of the pedigree is a grandmother (individual I-2) who has dimples. Two of her three children have the same trait (individuals II-3 and II-5) and three of her grandchildren have also the same trait (individuals III-3, III-4, and III-5).

X-linked recessive trait The diagram displays the inheritance of colorblindness in a family. Colorblindness is a recessive and X-linked trait (Xb). The allele for normal vision is dominant and is XB. In generation I, non of parent has the trait, but one of their children (II-3) is colorblind. Because there are unaffected parents that have affected offspring, therefore, the trait is recessive. the trait affects males more than females (because males are exclusively affected), implying that the trait may be X-linked.

Practice 1) Attached earlobes is an autosomal recessive trait What is the genotype of individual II-3: 1- EE 2-XEY 3-ee 4-Ee

2) Dimples is an autosomal dominant trait What is the phenotype of individual II-3: 1- dimples. 2-dd 3-DD 4-No dimples.

3) DMD (Duchenne Muscular Dystrophy )is X-linked recessive trait If individual II-3 has a child with a carrier woman, what is the percent chance that the child will be a daughter with DMD? 1- 0% 2-25% 3-50% 4-100%

4) What pattern of inheritance is shown in the pedigree? 1-Autosomal dominant 2-Autosomal recessive 3-Sex linked dominant 4-Sex linked recessive

Answers 1- 4-Ee 2- 1-dimples 3- 2-25% 4- 2-autosomal recessive

Homework: Which genotype represents a heterozygous individual? A. FF B. Ff C. ff D. A and C What does a completely shaded-in symbol on a pedigree of an autosomal recessive trait mean? A. An individual who shows the trait. B. An individual who does not show the trait. C. An individual who does not show the trait, but is a carrier. D. An unrelated individual.

Having a freckle is an autosomal recessive trait. If individual III-6 married a man who was homozygous for unattached earlobes, what is most likely to be true regarding their children?. A- All of their children would have unattached earlobes. B- All the female children will have unattached earlobes, and all the male children will have attached earlobes. C- The children would all have partially attached earlobes. D- All of their children would have attached earlobes.

Answers B. Ff A. An individual who shows the trait A- All of their children would have unattached earlobes