July 9, 2009

Oligosaccharides gone?

Cristina mentioned that Bertrand's most recent oligosaccharide test came back with no abnormal bands. I thought I should explain what that could mean.

Oligosaccharides are an intermediate product of cellular metabolism. Every cell produces and recycles them during its energy cycle. People with a lysosomal storage disorder can't produce a protein essential to some stage of the energy cycle. Wherever the break in the cycle occurs, oligosaccharides from the stage before start piling up. When oligosaccharides pile up, they tend to accumulate in internal organs like the brain or the liver. Wherever they accumulate, they begin inflicting damage.

The oligosaccharide test has a reasonably high false-negative rate. This means that often times, the test fails to detect them when they're really still present. Bertrand has tested positive for them four times now, so this could be the statistically expectable false-negative. We'll be retesting several more times over the course of the coming weeks and months to rule this possibility out.

If the oligosaccharides really have disappeared, this is good news, but puzzling news. Bertrand's metabolic specialist, Dr. Longo, said he knows of some extremely rare cases where they appeared in infants, manifested as an early-stage lysosomal disorder and then vanished without a trace. This is the extremely rare of the extremely rare. We certainly hope that this is the case.

Again, if they really are gone, the mystery only deepens. Chemically, he still has many other abnormalities, particularly in the liver, but none of those abnormalities indicate his symptoms or his developmental delays. At the very least, the oligosaccharides could explain his symptoms. If they somehow vanished, there are more questions to answer: Will his nerves recover, or is he stuck with the injuries he's received? Will his next brain MRI still show patterns of insufficient mylenation? Will his palette strengthen, enabling him to talk? Will his EEG normalize? Will he gain control of his muscles?

We'll keep you all posted as we learn more.

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