Closure of the anterior fontanelle is delayed in all except –
Delayed closure of anterior fontanel / wide (large) anterior fontanel

The anterior fontanel nonnally closes between 12 to 18 months of age.
The presence of excessively large anterior fontanel and its delayed closure is a recognised clinical feature in following conditions.
Down's syndrome
Osteogenesis imperfecta
Hypogonadism
Hypothyroidism