Update: Tyrosine Hydroxylase

July 6, 2012

Porter anxiously awaiting his swallow test.

Porter spent his first Independence Day at Primary Children’s Hospital and today is 4 weeks old. Every day there seems to be something new to think about and test for, and the emotional roller coaster continues. We were so happy with the fact that Porter was sucking and swallowing from a bottle, but those hopes were dashed when we discovered he was aspirating milk into his lungs. Consequently, the oral feedings discontinued and he was back to the NG tube only while they allow the area to rest and medication is given to stop acid reflux.  He will have another test to check his swallowing next Monday.

In the meantime, Porter has started to exhibit neurological behaviors that make caring for him difficult. Any kind of stimuli seems to start a wave of body arching and posturing (changing diapers, moving, picking him up).  For several weeks we didn’t hear a peep from him except for periodic sighing, but now he is crying a lot and nothing we do seems to comfort him.  Once he is settled, he likes to be held with his knees tucked under him. He seems so peaceful while he is sleeping.

A few days ago, the goal of bringing him home was in sight (depending on the outcome of the next swallow test) and while we were waiting for that to take place, he would start evaluations with rehab and PT specialists.  As of today, that view has changed because the numerous tests -on blood and spinal fluid done in the first few days after birth- have started to come back and there are some interesting developments.

Doctors have found that Porter is deficient in Tyrosine Hydroxylase and they don’t know why. Is it because of the brain damage? Or is the brain damage responsible for this condition? Either way, they are doing more testing- including genetic testing on Abby and Thom. Doctors want to see if they both carry recessive genes for this very rare disorder. Presently there are only 30 known cases in the world. More probably have it, but have not been officially diagnosed.The fact that the ischemia in the brain impacted the basal ganglia  is the most likely answer- but who knows? The good news is that in most cases, this is treatable, and if successful, it would make Porter’s quality of life a whole lot better. Definition of TH:

Tyrosine Hydroxylase (TH) deficiency (also known as Recessive Dopa- Responsive Dystonia) is a rare metabolic disorder characterized by the lack of the enzyme involved in converting the amino acid tyrosine to Ldopa. TH is a critical enzyme in normal dopamine production. Lack of this enzyme means neurotransmitters are blocked from signaling one another appropriately. The neurotransmitters dopamine, norepinepherine epinepherine (collectively known as catecholamines) and serotinin are deficient in the central nervous system and periphery.

Patients with TH Deficiency can develop movement disorders, autonomic symptoms (blood pressure instability, temperature irregularities), extreme irrabnormal eye movements and neurological impairment.

So we will cross our fingers and hope that the pharmacists can compound a special medication to help restore normal dopamine levels. Dopamine itself cannot cross the blood-brain barrier directly and so it is necessary to treat with a compound called L-Dopa in combination with another medication called carbidopa. There is an adult version of this combination called Sinemet (which is used to treat Parkinson’s disease), but the doses on that are way too high for Porter.

So far, Porter is dealing with two major problems: HIE and TH. We are finding that patience is the name of the game- and if you are a Tullis, patience is not something that comes easily. (The Lord is always ever ready to teach us – isn’t he?) In the meantime, they will treat Porter’s muscle discomfort with Tylenol and we will continue to pray for peace in our hearts.

Posted by Grandma Cind