Gerund Vs Infinitive

[swati]

• Having more than the usual number of fingers or toes on the hands or feet is termed
polydactyly.

• To have more than the usual number of fingers or toes on the hands or feet is termed
polydactyly.


I want to know which of the above is a correct sentence and why?

Thanks

[Alan]

Only the first is both grammatical and natural.

Gerunds rather than infinitives are preferred as subjects when the main clause denotes something that actually exists/occurs, and infinitives where something unreal or hypothetical is discussed. Since this medical conditonal actually occurs, the gerund is preferable here.