40% vs 1%

Today we headed down to Baltimore again for our genetic testing results and a neurology follow-up. Again, another early morning commute down I-83 aka the construction highway, to an appointment that we may or may not receive answers or recommendations from.

I was exceptionally nervous today for the appointments. We have been waiting for genetic results since December 2017, when we began the genetic testing process. Fully anticipating not getting any real answers, I didn’t want to get my hopes up that we were going to find out what has caused Greyson’s disabilities.

I drove down I-83 with countless thoughts in my head. What if they did find something? What if they didn’t? Should we pursue more options or tests? What else could we be doing for him to make him the most successful? I attempted to keep my mind off of the “what ifs”, and tried to distract myself with vacation discussions with Derek.

Once in Baltimore, it was the same routine: drop the car off with vallet, check-in at security, then with the outpatient clinic, then finally the nurse brings us back to start the appointments. The moment we stepped into the consultation room, G started crying and throwing a tantrum. I thought we were well prepared for the trip, fully equipped with snacks, juice, books and toys, but nothing seemed to calm G.

Finally, Dr. Julie Cohen, the genetic counselor came in the room and after a very brief greeting, cut right to the chase. My leg was shaking as we waited for the answers to all of my questions I frantically thought about on the drive down. When we had the samples taken from Derek, G and I in December, we knew the odds were not very good for getting an answer- a 40% chance of getting an answer, to be exact. Julie said that we “sort of” fit into that 40%, but not really. What does that mean?! We have an answer and a reason “why”, but it’s not a 100% today.

The entire exome sequence analysis showed only one variant in Greyson’s DNA makeup. Gene STAMBP, specifically variant p.R78X, which is responsible for MIC-CAP disease: Microcephaly-Capillary Malformation Syndrome. This variant is a heterozygous, autosomal recessive gene that was inherited from a carrier parent, and a “likely pathogenetic variant” contributing to G’s symptoms.

In people with microcephaly-capillary malformation syndrome, microcephaly begins before birth and is associated with an unusually small brain and multiple brain abnormalities. Affected individuals develop seizures that can occur many times per day and are difficult to treat. The problems with brain development and epilepsy lead to profound developmental delay and intellectual impairment. 

In G’s case, he only had one variant, which means only one parent was a carrier, often leading to a non-effected child. Because this disease is so incredibly rare, less than 1% to be exact, it is extremely difficult to detect. Because the exome sequence only looked at the overview of the chromosomes, there may be more variants that he has, that are currently unfound or undetectable with current technology. This all said, Julie did not feel that it was something that is too concerning, however, she did find that it was interesting that G presents many of the symptoms, but only had one variant. Because technology and genetic discoveries are everso changing, the lab will store our samples and retest them in two years when more information may become available.

That, in a nutshell, was the first appointment of the day.

Tempted to Google and self-research, I refrained and read the generic report that we were provided with. The nurses then came in to get Greysons vitals, which was difficult because he had fallen asleep after his 45-minute tantrum. About an hour later, Dr. Comi came out to bring us back to our appointment with her. We updated her on his development, behaviors, seizures and migraines and similar to what Dr. Stein stated earlier this month, confirmed that G was stable on his current meds and dosages.

She then pulled up the genetic testing report and connected the dots between the STAMBP variant and Greyson’s current symptoms. Commonly, children with MIC-CAP have one or more of the following symptoms:

Severe Microcephaly (G does not have)

Congenital Cutaneous Capillary Malformation (His Port-Wine stain)

Infantile-onset epilepsy (He has)

Profound developmental delays (He has)

Whorled hair pattern (He has)

Dysmorphic Features, such as cleft palate, thin lips, low ears, flat hairline and extra webbed fingers and/or toes (G doesn’t have any of these)

Loss of normal protein function (He doesn’t have)

White matter brain loss (G has)

Thin corpus collosum and other non-specific brain abnormalities (He doesn’t have)

Coincidentally Greyson shows several of these symptoms, but because only one variant was found and research is extremely limited on MIC-CAP, Greyson is considered a carrier but not effected. Though not effected as of today, there have been cases that show a child to have MIC-CAP that has been inherited from only one parent and not both. This is extremely rare and not common, but we seem to hit the genetic jackpot everywhere else, so why not this too? The report goes on to state that:

“We interpret R78X as a likely pathogenic variant, related to the port-wine stain, seizures and global developmental delays found in this client.”

So basically, G fits into both the category of 40% no definite answer found and the 1% of the extremely rare variant that causes MIC-CAP. As of 2019, we know that it is so rare that he has an extremely mild form of MIC-CAP, but in two years, he could have the diagnosis. In conclusion, the report also offers another open-ended question after stating:

“While no other potentially disease-associated variants were identified by exome sequencing of the STAMPB gene, it is possible that this individual harbors a second variant that is undetectable by this test.”

So, he could have this rare disease, but a less crippling form? As of 2019, it’s a maybe, but come 2021, it could likely be a definite.

One last test that could show the second variant needed for the positive diagnosis, is a skin biopsy of G’s port-wine stain. Yes this is invasive and he would have a small scar, but what would be the benefit of that definite answer? Is it worth it, or should we just be content with knowing this is likely what has caused all of these issues? What good will a biopsy do if there’s not cure or treatment available for MIC-CAP? Again, we are leaving with more questions rather than answers.

After digesting all of the information accrued over the two appointments, I found it relieving to hear the fire alarm go off. A fire drill of all days, with our child that is extremely sensitive to light, sound and crowds, being carried outside on the streets of Baltimore for a fire drill. We found a nice bench and popped a squat until the alarms stopped and we were cleared to go inside and be discharged for the day.

After discussing all of this information with my mother (who always has the magic touch when needing to calm someone down to think about things), she gave me some great advice: “take a few days and process this information. These answers specifically will not make a difference to the past and the future at this time.” So, why worry about the future and the past? We can’t change our genes and our family inherits, so we will live for today. We will continue to support our son and help him the best that we can and pray that we find the peace of mind with this information.