Alyhia's Eye

Introduction

Coloboma Syndrome or Cat Eye Syndrome (to be more specific) is malformation to the eye. It is caused by an inverted 22 and with a break in 22q11 (scientific terminology). This is a defect that is most commonly inherited although it can form due to other factors. It can cause many health problems related to more than just vision. It can affect sight, hearing, cause heart problems, kidney problems, growth disabilities, mental disabilities, and much more. One way to identify this syndrome is to do genetic testing.

Part One

Coloboma is a very rare disease. In Switzerland only about 1 in every 50,000 – 150,000 live births have this malformation. However a recent study suggests that 1 in about 7400 people have this disorder (Nicks, 2011). It was first described in 1879 by Dr. O. Haab. Later more information was gathered to know its cause stemmed from the 22 chromosome. This defect led the eye to be abnormally shaped.

History

O. Haab, a Switzerland ophthalmologist, was the first to describe a syndrome where anal atresia (another possible symptom) combined with Coloboma in 1879 (Bissonnette & Dalens, 2006).  An extra bisatellited marker chromosome was found in patients with CES, in 1965 (Chen, 2006). However, the name “Cat Eye Syndrome” (CES) was created by the two men, W. Schunid from Zurich, Switzerland and M. Fraccaro from Pavia, Italy. They discovered that it was caused by too many of the 22 Chromosome (Bissonnette & Dalens, 2006). Obviously its name came about due to the shape of the pupil (explained in more depth later on in this section).

Cause

The cause of this mutation lives within the 22^nd chromosome. For starters, individuals who do not have CES have two 22^nd chromosomes. Both chromosomes have a long arm known as 22q and a short arm know as 22p. However, the 22^nd chromosome for individuals who do have CES also have the 22p present along with the short region of the 22q three or four times instead of just twice (NORD, 2010). The extra 22 chromosome usually comes from one of the parents (Bissonnette & Dalens, 2006), making this an inherited gene which is present at birth (Nicks, 2011). (Please refer to table one in Appendix A for a more detailed layout of the 22^nd chromosome.) “Treatment is given according to the symptoms the individual is diagnosed with. Doctors recommend surgery to repair inborn defects in the heart or anus. Patients with short stature are given growth hormone therapy” (Nicks, 2011, pg1).

Identify

So how is it determined if someone has Cat Eye Syndrome? One way is through a genetic type of testing which is called FISH (Fluorescence in Situ Hybridisation). “FISH is a relatively new molecular cytogenetics technology utilizing fluorescently labeled DNA probes to detect or confirm gene or chromosome abnormalities that are generally either beyond the resolution of routine cytogenetics or can be applied to samples that are unsuitable for conventional cytogenetics analysis” (HMDS, 2005, pg1). Syndromes such as coloboma, anal atresia, and preauricular pits/tags (go into more detail later on) can lead to a Cat Eye Syndrome diagnose. However, the FISH test is what narrows it down to Cat Eye Syndrome specifically.

Part Two

Cat Eye Syndrome has many external symptoms such as the shape of the eye (‘s). There are also internal complications that can arise from this syndrome such as heart complications. While this syndrome may seem very daunting at times we will get the chance to look at a young lady, Alyhia, who is a lighter side to the possible outcomes that can occur due to this syndrome.