DNA Results

As I stated we had three DNA tests done on Baby Nelson to determine if there was another factor besides just his kidneys.  I received a phone call from our genetic counselor on Tuesday, January 21st to discuss the results from the testing.  I am going to attach part of the email that she sent me since she does a much better job explaining it than I ever could for you.  

"The results showed 46,XY,add(4)(q35), which indicates a male baby with 46 total chromosomes (the correct number). On one copy of chromosome 4, the lab noted additional chromatin (genetic material) of unknown origin. The location of the extra material is 4q35. The other copy of chromosome 4 did not have this extra material. According to the lab, this material is suggestive of satellite DNA, which is a type of DNA that is made of many repeating sequences of letters and is not involved in making proteins in the body (non-coding). However, we are unable to tell that definitively on chromosome analysis alone. It is also possible that this material represents an unbalanced translocation. An unbalanced translocation occurs when two chromosomes exchange information with each other and some genetic material is gained or lost.

  

Often babies with an unbalanced translocation will be miscarried early in the pregnancy due to abnormal development.  However, there is chance that a pregnancy will continue to term and result in a baby with birth defects or other health issues. The specific effects will depend on what genes are in the area that was lost or gained. Chromosome microarray analysis is a technique to read through the chromosomes and detect gains and losses of material and determine which genes are affected. It can also determine whether a gain or a loss is likely to have clinical significance (health effects) or not. 

Unfortunately, Chromosomal Microarray Analysis (CMA) was not possible due to insufficient DNA from the fetal blood sample. 

Occasionally, in a completely healthy individual, the chromosomes will be arranged in a balanced translocation, where material is exchanged between chromosomes but nothing is gained or lost.  As long as the correct amount of genetic information is present, this rearrangement of chromosome material will not affect the health of the person who carries it.   When a carrier of a balanced translocation produces egg or sperm cells, there is an increased likelihood that the resulting egg or sperm cells will have an unbalanced translocation. 

If this chromosome finding happened new in your son, the chance of it happening again in future pregnancies is low. If either you or your husband is a carrier of a balanced translocation, future pregnancies would be at an increased risk for miscarriage or health issues. People with a balanced translocation can also have healthy babies with either normal chromosomes or a balanced translocation like their parent. The way to determine this is to analyze yours and your husband’s chromosomes."

So with this being said, we can request the CMA to be done again after Baby Nelson is born to find out exactly where the extra material on chromosome 4 came from.  If further screening needs to be completed we can request that also.  This will also help down the road in further genetic testing of us (as the parents), if we consider having children in the future.

Thank you for the continual thoughts and prayers for our precious son.