Your Online Health Information Site


Short Arm Chromosome 4

The congenital abnormality of a “short arm chromosome 4” is also medically known as “Wolf Hirschhorn Syndrome”. This syndrome occurs at a rate of 1 in 50,000 births and there is a higher incidence among females with a male to female ratio of 1:2.

There is a deletion of the short arm of chromosome 4, which is necessary for midline closure in the fetus, so there are midline closure defects, distinct facial abnormalities, seizures and mental retardation.

Signs and symptoms

The newborn baby has a small head (microcephaly), low muscle tone (hypotonia), and a cleft palate or cleft lip. About 20% of all cleft lip cases are due to genetic abnormalities like this syndrome, with respect to all cases of cleft palates in the population at large underlying genetic abnormalities like this syndrome are found to be present at even a higher percentage (in about 50%). Here is an image of a boy with Wolf Hirschhorn syndrome (thanks to for this image).

The eyes are wide apart (ocular hypertelorism), there are highly arched eyebrows and there is a downturned mouth (fish mouth). The jaw is underdeveloped (hypognathia) and the ears have tags and/or pits. After birth the child stays behind in growth (growth retardation) and the muscles are underdeveloped. The child is slow in developing and mental retardation of various degrees is evident in all of the cases. Many other abnormalities occur in patients with Wolf Hirschhorn Syndrome: skeletal abnormalities occur in 65%, congenital heart disease is present in 50%, conductive hearing loss in about 45%, brain structure abnormalities in 35% and urinary tract malformations in 25%.


There is a mortality of about 30% in the first two years of life due to major malformations in the heart, brain, face and due to aspiration pneumonia and other infections. Depending on the severity of these malformations, the person afflicted with this genetic abnormality will have a longer or shorter life expectancy.



1. Behrman: Nelson Textbook of Pediatrics, 17th ed., © 2004 Saunders, An Imprint of Elsevier: Chapter 70 – Chromosomal Clinical Abnormalities


Last modified: October 22, 2014

This outline is only a teaching aid to patients and should stimulate you to ask the right questions when seeing your doctor. However, the responsibility of treatment stays in the hands of your doctor and you.