This pedigree depicts the inheritance of the mitochondrial disease Leber hereditary optic neuropathy (LHON). Individual I-1 does not show any symptoms of LHON, whereas her daughter and all three of her grandchildren are affected. Provide two explanations for this.

The following pedigree shows the inheritance of Huntington’s disease, a fatal genetic disorder that causes neurodegeneration. Since signs and symptoms usually do not appear until adulthood, many who are carriers may not realize their risk of passing on the disease-causing allele.  The following pedigree represents a family in which some people are affected by Huntington’s disease.   Using just the information on this pedigree, is Huntington’s disease caused by a dominant allele or recessive alleles? What are the genotypes of the grandparents (I-1 and I-2)? What are the genotypes of the parents (II-6 and II-7)? If the parents above have another child, what is the chance that they will be affected by the Hungtington’s disease allele? What are the genotypes of the unaffected children (III-8, 9, 10)? What is the chance that the unaffected children above will pass on a Huntington’s disease allele to their children? What is the genotype of the affected child (III-11)? What is the chance…

Below is a pedigree chart for a family that has a history of Alkaptonuria.   Individuals infected with this condition can have darkened skin, brown urine, and can suffer from joint damage and other complications.  Given this pedigree answer the following questions.   Given the data in the pedigree chart is this genetic condition autosomal dominant or autosomal recessive? What are the genotypes for #1, #2, and #3?  If either of the 4th generation "aa" females were to mate with a homozygous dominant male would any of their offspring illustrate the phenotype?  Why or why not?

This question relates to the inheritance of two linked genes, the ‘E gene’ and the ‘B gene’. Each gene has a dominant allele, shown with the upper-case letter (E and B, respectively) and a recessive allele, shown with the lower-case letter (e and b, respectively). Two pure line parents were crossed together to produce a dihybrid F1 individual. This F1 individual is crossed with a tester parent. The F2 test cross progeny are stated below. Use this information to answer the following questions. F2 Test cross progeny Genotype       Number eB/eb              75 Eb/eb              76 EB/eb             25 eb/eb              24 Which one of the following options most accurately states the genotype of the dihybrid F1 individual in this scenario? eB/eB Eb/eb EB/eb eB/Eb