1p36 deletion syndrome: Year of the Zebra

1p36 deletion syndrome is a rare genetic disorder where a small portion of the short arm of chromosome 1 is deleted.

Now, our DNA is packaged into 23 pairs of chromosomes, one from each parent, for a total of 46 chromosomes. Each chromosome contains thousands of genes which are essentially the recipes for making every protein found in the body. Chromosomes are divided into two sections, or arms, hooked together in the middle by a centromere. The shorter arm is called “p”, from the French “petit” that means small; and the long arm is called “q”. In 1p36 deletion syndrome, the final portion of the short, or “p,” arm of chromosome 1 is deleted, resulting in a loss of genetic material that is essential for development.

In most cases, 1p36 deletions are a result of a de novo mutation, which means they occur on their own without being inherited. However, in a small number of cases, the deletion can be inherited from one of the parents.

Alright, now signs and symptoms of 1p36 deletion syndrome vary depending on the amount of missing genetic material. Typically, individuals with 1p36 deletion syndrome will have a short stature and unique facial features like a small head with a large, rounded forehead and small, pointed chin; deeply set eyes; straight eyebrows; and epicanthal folds, which are skin folds of the upper eyelids that cover the inner eye. The nose is usually flat with a wide nasal bridge, and there can be orofacial defects like cleft palate, which is an opening in the roof of the mouth.

Common symptoms include moderate to severe intellectual disability; slower motor development; dysphagia, or difficulty swallowing; and hypotonia, or weak muscle tone, which usually improves with age. Individuals may also exhibit seizures; vision and hearing problems; dysarthria, or difficulty speaking; and self-harm or other behavioral problems; as well as delayed closure of the fontanelles, or soft spots in the skull.