فائدة الطبقة الرقيقة اللوني للكشف المبكر عن اضطراب الاحماض المينية

The Utility of Thin Layer Chromatography for Early Detection of Amino Acid Disorder

Abstract

Metabolism is organized into pathways where the components are transformed
by the action of different enzymes that catalyze the transformation of the
substrates (synthesis or degradation). When one or more of these enzymes are
not working properly or are absent, metabolic disorders can occur. Most
inborn error of metabolism are inherited in an autosomal recessive manner.
The overall incidence of inborn errors of metabolism is estimated to range
from 1:800 to 1:1000 live births, although the incidence is probably much
higher given difficulties in clinical diagnosis and limitations in diagnostic
testing. The incidence and prevalence of IEM were vary in different countries.
Classification is based on the affected metabolic process or enzymes involved
in generating toxic substances such as the individual disorders of amino acid,
Disorders of carbohydrate metabolism, Disorder of lipid metabolism and
Disorders in the metabolism of purines and pyrimidines.
The aim was introduce a separation a TLC method of standard amino acids
that could be effective for the detection of amino acid disorders by producing
distinguishable strategies based on silica gel TLC plates.The present work
included a cross section study. Samples were selected, from patients attending
the rare diseases unit, Kerbala teaching hospital for children. and the
standardization of 20 amino acid was done by TLC (10 time for each amino
acid). After that, separation of amino acid in the serum and urine were
performed for patient group.The study were included 56 samples, ages ranging
from 7 day to 15 years. The patient samples were divided as follows :Neonate
of age < 1month were 7 ,new-born aged from 2-12 months numbered 39,
children aged >1year were 10, females were 22 and males represent 34, our
study shows that 41% of the suspected IEM patients were with sign of
jaundice, and 32% ,29% ,18%,16% ,5%, 5% with flatulence, vomiting ,
XI
diarrhea , acidosis, dehydration and hepatomegaly respectively. Results was
shown about 50% , 41%, 39% ,36% ,18% of suspected IEM patients were with
hypotonia ,spasticity, intellectual delay, epileptic seizures and lethargy
respectively .
Standardization of amino acids on TLC was performed based on different
strategies: the study results were established different strategies showing good
demonstration of the standard AA throughout the retention factor (Rf) (mean
and /or range), the arithmetic retention factor resulted in subdivided of AA
into 6 group accordingly. Also the sstandardization of AA were separated
based on producing various distinguishable colors/ shapes. The above three
methods help to identify amino acids in the serum and urine samples. It has
been reported that one third of the IEM were amino acid disorders, and these
disorders must be diagnosed and treated as early as possible to prevent the
unpleasant complication. Generally, to get diagnosis, HPLC & TMS must
done for the suspected patients if have amino acid disorder, both methods are
expensive, time consuming and available only in a few locations in Iraq. In
order to exceed these adverse effects, this study suggested starting with TLC
(easy , unexpensive , time effective) which could help to screen suspected
patients with amino acid disorders, then the more specific and sensitive
methods (HPLC & TMS ) could be used only to prove diagnosis.