We found out on September 22nd that Daylon has an extremely rare genetic cause for his small size.
I have been trying to figure out the best and easiest way to describe what it is that they found in Daylon, and have had an extremely difficult time trying to figure it out, so it has taken me a while to write this post.
I thought of scanning in the letter we received from genetics, but it would be difficult to read because I would have to upload it as a picture and it would be very small. So I am going to take the genetic lab results and explain them to the best of my ability.
Daylon is mosaic meaning he has more than one cell line. Normally we have one cell line, 46XX for women or 46XY for men. Daylon has 3. He has one normal line and two other abnormal cell lines. The first abnormal cell line is 46X with an inverted duplication of the Y chromosome. The second abnormal cell line is 47XY with a marker gene that contains more Y material. The next paragraph will be typed out exactly as it appears on the microarray report.
Daylon has a duplication of part of the Y chromosome extending from the PAR1 (psuedoautsomal region 1) to Yq11.221. The PAR1 region normally appears disomic in males on the X chromosome by cytogenic array. Daylon appears to have three copies of the PAR1 region in addition to gains on the Y chromosome, suggesting a large duplication on the Y chromosome. Included in the PAR1 duplication is the SHOX gene which, when deleted or mutated, has been associated with short stature. However, there is at least one report in medical literature of a patient with trisomy of the SHOX gene having short stature.
We were told that the best "syndrome" to look up for Daylon is 47XYY syndrome, but to remember that not all of his Y chromosome is duplicated and not all of his cells contain the duplication. While most children with 47XYY are tall, the thought is that with Daylon's duplication where it is, it has interrupted a signalling pathway and turned off his SHOX (or growth) gene.
I will include links for the information on what the different abbreviations and genetic information all means.