What characteristic is NOT typical for genetic diseases in families?

• A. Trend of occurrence in generations
• B. Isolation of cases
• C. Increased risk among relatives
• D. Similar expressions among family members

Answer: (B)

Genetic diseases often exhibit a trend of occurrence within families, indicating that they can be inherited from one generation to the next. This means that traits or conditions may manifest in several family members across generations, which is a key characteristic of many genetic disorders. Additionally, there is typically an increased risk of these diseases among relatives due to shared genetic material, which enhances the likelihood of inheriting the same genetic mutations. The expression of genetic diseases may also show similarity among family members, due to the shared genetic background and environmental factors, leading to comparable manifestations of the condition.

The option mentioning isolation of cases stands out because genetic diseases are generally not isolated incidents; instead, they tend to cluster within families. Cases are often observed in multiple family members, which is contrary to the idea of isolation. Therefore, saying that a genetic disease presents as isolated cases is inconsistent with the typical patterns seen in familial genetic diseases.