Which of the following is also considered a congenital disorder?

Psoriasis is correct in the context of being considered a congenital disorder, as it is a chronic auto-immune condition that can have genetic factors involved. Although it commonly manifests on the skin, its effects can also extend to the nails, leading to changes such as pitting, discoloration, and abnormal nail growth. Understanding psoriasis as a congenital disorder is critical because it highlights the hereditary nature of the disease, where individuals may have a predisposition to develop the condition due to their genetics.

The other conditions mentioned are primarily associated with external factors or environmental triggers rather than genetic inheritance. Onychatrophia refers to the atrophy of the nail, which can result from injury or infection, while paronychia is an infection of the skin around the nail, usually caused by bacteria or fungi. Onychocryptosis, or ingrown nails, occurs mainly due to improper nail cutting or trauma rather than being inherited. Therefore, these conditions do not align with the characteristics of congenital disorders that are linked to genetic predispositions.