Question

What pattern of inheritance does hereditary retinoblastoma exhibit at a phenotypic level?

A Autosomal recessive with nearly complete penetrance
B Autosomal dominant with nearly complete penetrance
C Autosomal recessive with incomplete penetrance
D Autosomal dominant with incomplete penetrance
E X linked recessive

Answer 1

Hereditary retinoblastoma is inherited in an autosomal dominant pattern with nearly complete penetrance, meaning that the presence of one mutated gene is sufficient to exhibit the disease. This pattern is similar to other disorders such as achondroplastic dwarfism and Huntington's disease.

Step-by-step explanation:

The pattern of inheritance that hereditary retinoblastoma exhibits at a phenotypic level is autosomal dominant with nearly complete penetrance. This means that only one copy of the mutated gene on an autosome (a non-sex chromosome) is necessary for an individual to express the trait. Such disorders are evident even when the individual has just one faulty gene, as opposed to autosomal recessive inheritance where two copies of the faulty gene are required for the trait to be expressed.

With autosomal dominant disorders like hereditary retinoblastoma, an affected individual will either be heterozygous or homozygous dominant. Examples of other genetic diseases inherited in this pattern include achondroplastic dwarfism, Marfan syndrome, and Huntington's disease. In these conditions, the presence of a single dominant faulty gene can lead to the expression of the disorder.