Lecture, chapter 4 - Pedigree analysis in human genetics

Today we finished chapter 4.

We covered the remaining modes of inheritance in human mendelian genetics: X-linked recessive, Y-linked, and mitochondrial. We studied examples of some of those.

We than discussed variations in phenotypic expression, mainly age-related phenotypic expression, penetrance, and expressivity, and provided a few examples, including , interestingly enough, one of the students! (good times!)

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Lab 02 - Mendelian genetics

Today we completed lab 2, in which principles of mendelian genetics were studied through computer simulations of fruit fly (Drosophila melanogaster) crosses.

We used DrosophiLab to simulate crosses between wild type flies and mutants for the autosomal genes vestigial wings and sepia eyes, and the X-linked gene white eyes. By doing so students were able to demonstrate the principles of segregation and independent assortment.

• Video on how to use DrosophiLab

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Lecture, chapter 4 - Pedigree analysis

Following on the pedigree analysis chapter, we discussed the advantages of using a catalog of human Mendelian traits: The Online Mendelian Inheritance In Man (OMIM) catalog, hosted by the NCBI website. In OMIM you can find a wealth of information on human traits that are inherited in a Mendelian fashion, from the symptoms of a genetic disorder and how to diagnose it, to details in the molecular genetics and published papers on the trait or disease.

Then we introduced the several modes of inheritance of human Mendelian traits.

• Autosomal - dominant and recessive
• X-linked - dominant and recessive
• Y-linked
• Mitochondrial

We described the characteristics of the autosomal and X-linked dominant modes of inheritance.

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LectureChapter 3 - Mendelian geneticsChapter 4 - Pedigree analysis

Yesterday we finished chapter 3, on Mendelian genetics.

We discussed more complex phenotypes that made Mendel's principles harder to study in many organisms, and how they do not conflict with them when considering the genotypes. Such phenotypic variations to Mendel's theme are:

• Incomplete dominance
• Codominance
• Multiple alleles
• Gene interactions (mainly epistasis)

We also started chapter 4, on pedigree analysis.

We briefly revisited the reasons for which human genetics cannot be studied experimentally and introduced the modes of inheritance of human Mendelian traits.

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