I have a sample of children with a condition, lets say asthma. so I have n=100, but I have 75 girls and only 25 boys.

Can I use a statistical test to show a significant difference? i.e. That there is more significantly more girls in the sample. If I know the ratio for births is 50:50 for girls and boys in our population, can I say that significantly more girls develop asthma than boys?