Tyrosinemia Type 1 “Yesterday, Today and Tomorrow". 

Conference report by Jennifer Heberer

I attended a conference aimed at medical professionals on Tyrosinemia Type I organized by Swedish Orphan International held in Stockholm from 16-17 April 2007.  Speakers included Dr. Elizabeth Holme and Dr. Grant Mitchell.  The following comments are taken from my notes of the meeting.  I have not yet received an official report of the meeting, so I have not been able to check them against that report.  Please also be aware that I am a parent not a medical professional, and the following should in no way be taken as advice. 

With regard to treatment of Tyrosinemia Type I, there do not seem to be any big developments.  There remains a bit of divergence on when to transplant and also on acceptable NTBC concentrations in blood and tyrosine levels.  Some recommend transplantation at the first evidence of a nodule, others appeared to have a more wait and see approach.  With regard to NTBC concentration, some shoot for 45 mmol/l, others 50 mmol/l.  Concerning tyrosine levels, 350mmol/l was mentioned as the target (under 500 mmol/l acceptable). 

Discussions on monitoring underscored the importance of a multi-pronged approach, including the monitoring of AFP levels, all amino acid levels, succinylacetone production, PBG-synthase, 5-ALA together with imaging (MRIs annually, ultrasounds biannually) – as called for by the protocol.  The importance of dietary compliance and medicated formula was also stressed. 

Because of the high incidence of Tyrosinemia Type I in Quebec, the screening program there screens all babies using succinylacetone as a primary metabolite.  They are therefore able to start diagnosed cases on NTBC immediately, preventing the usual damage caused at the onset.  It is possible that neonatal screening together with early NTBC treatment may be able to eliminate the need for liver transplantation.  However, further study is needed before this conclusion can be reached. 

Interesting points of mention:

•A case that involved the presence of cancerous nodules despite normal AFP levels;

•A case of 3 siblings presenting completely differently - one with liver failure, another with kidney failure, another with neurological problems;

•A case of an asymptomatic older sibling.

 

July 3, 2007