Well, of all the trisomies, it was likely that he would have the trisomy 21, which is the most common autosomal trisomy and the most common genetic cause of severe learning difficulties. The moment he was born, we already suspected it. His face was so hypotonic, and he had a single palmar creases and a wide sandal gap between the big and second toe. The doctor said they were going to send his blood for a test, and the results may take 1-2 days. He said something about FISH, but my mind was already full with other questions. He told me that 30% of Down's children has congenital heart diseases, particularly atrioventricular canal defect. Fortunately, at least 50% of affected individuals live longer than 50 years. We weren't sure of the diagnosis yet, but he recommended us counseling.
What does it matter if my child is at increased risk of hypothyroidism, impairment of vision and hearing and of atlanto-axial instability? I love him anyway, since he is my own child. But why him? Is it my fault?
The doctor assured me that it is not likely to be my fault, since a trisomy 21 may result from meiotic non-disjunction (94%), translocation (5%) or mosaicism (1%). Only the translocation is inheritable, which is known as a Robertsonian translocation, which means that the extra chromosome 21 is joined onto another chromosome (14, 15, 22 or 21). If I have this translocation, the risk of recurrence is 10-15%, and if my husband is the carrier, the risk will be 2,5%. There is also a rare 21:21 translocation, and if one of us has it, all the offspring will have Down syndrome. I just hope this is not the case.
In mosaicism, some cells are normal and some have trisomy 21. Isn't it weird that not all cells has the same DNA? But my son probably doesn't have the mosaicism.
The most likely cause of my son's Down syndrome: meiotic non-disjunction, which means the pair of chromosome 21s fails to separate, so that one gamete has two chromosome 21s and one has none. The doctor told me it was related to maternal age, since I am under the age of 35 years, it was probably just bad luck.
He is the most beautiful child to me, even though most people won't agree with it. His cute flat nasal bridge, upslant eyes and round face. Every part of him is so tiny, and he seems so fragile. His small gesture, small mouth and little ears, but yet so alive. He is the sweetest thing ever, like every other child. However, I know that I have to prepare myself on the fact that he gets sick easily, and especially in the future. How will the future be? Who will take care of him when we aren't around anymore?
