Correlation between Dried Blood Spot Thin Layer Chromatography and Plasma High Performance Liquid Chromatography of Leucine/Isoleucine Levels Among Filipino Patients with Maple Syrup Urine Disease (MSUD) seen at the Institute of Human Genetics

Abstract

Introduction. Management of patients with maple syrup urine disease

(MSUD) includes a low protein diet, supplemented with special formulas

and constant monitoring of branched chain amino acids (BCAA). The

gold standard for monitoring BCAA is plasma amino acid analysis using

High Performance Liquid Chromatography (HPLC). In a developing

country like the Philippines, however, the cost of this test is prohibitive

to the majority of the patients. In our center, dried blood spot leucine/

isoleucine (leu/ile) levels analysed by thin layer chromatography (TLC)

is often used to diagnose and monitor these patients.

Objective. This study was done to determine the correlation of leu/ile

levels using the two methods (TLC and HPLC).

Methods. A total of 46 MSUD patients were referred to the Biochemical

Genetics Laboratory of the Institute of Human Genetics (IHG) from July

2001 to January 2004. Thirty five samples were obtained from 18 of

these patients [some patients were seen at IHG more than once], and

paired determinations of plasma amino acid using TLC and HPLC were

made. The remaining samples were either hemolyzed or were not

analyzed. The correlation coefficient [rho denoted as “?”] was estimated

at a 95% confidence level using the Fisher’s Z transformation.

Results and Conclusion. Of the 18 patients, 12 were males. The youngest

was 1 day old and the oldest was 5 years old. The majority had the

classical type of MSUD and dietary protein was restricted to between

0.6 gram/kg/day to 1 gram/kg/day of natural protein. Using the first

pairs of observation for these 18 patients, the correlation coefficient

was 0.76 {95% CI:0.462 to 0.907). This suggests a strong correlation

between the two methods. It is recommended that further studies be

done to determine the potential of the dried blood spot leu/ile level

by TLC as an alternative method that can be used in the diagnosis and

monitoring of MSUD patients especially in a developing country.