In the world visited in The Flintstones there is an autosoma

In the world visited in The Flintstones, there is an autosomal recessive disorder called reduced speech. This condition (probably inherited from Neaderthals) changes the shape and position of the larynx so that many fewer sounds can be made; it is very rare. Fred\'s maternal uncle had this disorder, as did Barney\'s paternal grandfather. If Fred\'s daughter Pebbles and Barney\'s son Bamm-bamm were to have a child together, what is the chance that their child would be affected?

Solution

If we draw a pedigree chart, we could understand the situation. Here, since Fred\'s mother was normal and there is no mention of other maternal uncle or maternal aunt of Fred and also because it is a autosomal recessive disorder, we have to conclude both Fred\'s maternal grandfather and maternal grandmother were carriers for the gene. In this case there is only 25% chance of Fred to be a carrier for the gene. If Freds\' wife is normal and not a carrier for the gene, there is 25% chance of Pebbles to be a carrier for the gene.

However, Barney\'s father was a carrier of the gene. This is because Barney\'s paternal grandfather had this disorder, even his grandmother was normal, his father had to be a carrier, since it is a autosomal recessive disorder. Supposing, Barney\'s, mother was not carrier of the gene, there is 25% chance of Barney to ba a carrier. Supposing, Barney\'s, wife was not carrier of the gene, there is 25% chance of Bam-Bam to be a carrier for the gene.

If both Pebbles and Bam-bam were both carriers of the gene by chance, then there is 25% of their child to have this disorder i.e child to be affected. Otherwise, there child will not have this disorder. However, there are more chances of the child to be a carrier of the gene.