Define role of Vitamin A in controlling gene expression?

Vitamin A as retinoic acid has widespread effects on the synthesis of a variety of important proteins. These diverse effects are due largely to its combination with one or more nuclear receptors that serve as trans-acting factors that promote transcription. Several different receptors have been identified and each has a specific mode of action in growth and development. For example, should a mutation occur in the receptor, which would result in decreased retinoic acid binding, embryonic cell differentiation is affected, with the result of embryonic wastage or foetal malformation? Congenital heart malformation has been attributed to such a mechanism.