Question

2. A man expresses the three traits of porphyria, Marfan, and neurofibromatosis. His wife does not express porphyria or Mactan, but does show the growths of neurofibromatosis. Use the letters of Plp for the dominant and recessive alleles of porphyria, M/m for the alleles of Mactan, and N/n for the alleles of neurofibromatosis. In each of these cases, the upper case letter should represent the dominant allele and the lower case letter should represent the recessive allele. In this stated order, what are the genotypes of the man and then the woman? How many different gametes could be made by the man? How many different genotypes could be possible in a cross between this man and woman? Do not list the possible genotypes, but merely count how many different genotypes exist in this couple's potential children. List all of the potential phenotypes which could exist in this couple's children. In the order, which was stated in the answer immediately above, in what ratio would these phenotypes appear in the couple's potential children? Focus + 10
Note - if a dominant phenotype is stated, but but the genotype is unknown or can not be determined, then the heterozygous genotype will always be used.

Answer 1

Porphyria is a recessive disease. Marfan and neurofibromatosis are both follow dominant pattern of inheritance.

Man expresses porphyria means, he has to be homozygous to the condition since it is recessively inherited. Marfan and neurofibromatosis both are dominantly inherited. So they can be homozygous dominant or heterozygos dominant also. It can't be confirmed unless the pedigree charts for other generations also is included.

Wife does not show porphyria, so she cal also be homozygous normal or heterozygous normal. Marfan is also not seen in wife, so she has to homozygous normal having no disease. Neurofibromatosis is dominantly inherited. So the wife may be homozygous dominant or heterozygous dominant to the disease. Based on this, the genotypes of the man and his wife can be:

Man- ppMMNN or ppMmNn He can be homo or hetero for both marfan and neurofibromatosis.

Wife-PPnnNN or PpnnNn Wife can be heterozygous normal for porphyria or homozygous normal as it is recessve allele. She can be heterozygous for neurofibromatosis or homozygous also as she is expressing and the disease is dominant.

Gametes made:

The total different types of gametes made by the man are --pMN, pMn, pmN, pmn

Number of different genotype combinations possible  between the man and wife , if they produce children can be:

12different genotypes can be formed considering that the man is heterozygous for M and N genes and woman heterozygous for P and N genes.

Phenotypes of the children:

1. Normal to all diseases. No disease at all.

2.Normal to porphyria,normal to morphan, suffer neurofibromatosis.

3.Normal to porphyria, sufferer to morphan, normal neurofibromatosis.

4.Normal to porphyria,sufferer to morphan, sufferer of neurofibromatosis

5. Sufferer of porphyria, normal to morphan and normal to neurofibromatosis.

6.sufferer porphyria, normal to morphan, sufferer of neurofibromatosis.

7.Sufferer porphyria, sufferer morphan, normal to neurofibromatosis.

8. Sufferer of all 3 diseases like the man mentioned in the question.

8 phenotypes of the children are possible.