1.Separation of sulfated urinary glycosaminoglycans by highresolution electrophoresis for isotyping of mucopolysaccharidoses in Malaysia
Nor Azimah Azize ; Zabedah Md Yunus ; Norsiah Md Desa ; Ngu Lock Hock ; Suhaila Abd Rahman
The Malaysian Journal of Pathology 2010;32(1):35-42
Mucopolysaccharidoses (MPS) are a group of inherited disorders caused by the defi ciency of specifi c
lysosomal enzymes involved in glycosaminoglycans (GAGs) degradation. Currently, there are 11
enzyme defi ciencies resulting in seven distinct MPS clinical syndromes and their subtypes. Different
MPS syndromes cannot be clearly distinguished clinically due to overlapping signs and symptoms.
Measurement of GAGs content in urine and separation of GAGs using high-resolution electrophoresis
(HRE) are very useful initial screening tests for isotyping of MPS before specifi c enzyme diagnostics.
In this study, we measured total urinary GAGs by a method using dimethylmethylene blue (DMB),
and followed by isolation and separation of GAGs using high resolution electrophoresis (HRE)
technique. Of 760 urine samples analyzed, 40 have abnormal GAGs HRE patterns. Thirty-fi ve
of these 40 cases have elevated urinary GAGs levels as well. These abnormal HRE patterns could
be classifi ed into 4 patterns: Pattern A (elevated DS and HS; suggestive of MPS I, II or VII; 16
cases), Pattern B (elevated HS and CS; suggestive of MPS III; 17 cases), and Pattern C (elevated
KS and CS; suggestive of MPS IV, 5 cases), and Pattern D (elevated DS; suggestive of MPS VI;
2 cases). Based on the GAGs HRE pattern and a few discriminating clinical signs, we performed
selective enzymatic investigation in 16 cases. In all except one case with MPS VII, the enzymatic
diagnosis correlated well with the provisional MPS type as suggested by the abnormal HRE pattern.
Our results showed that GAGs HRE is a useful, inexpensive and practical fi rst-line screening test
when MPS is suspected clinically, and it provides an important guide to further enzymatic studies
on a selective basis.
2.Molecular analysis of fragile X syndrome (FXS) among Malaysian patients with developmental disability
Ernie Zuraida Ali ; Yusnita Yakob ; Norsiah Md Desa ; Taufik Ishak ; Zubaidah Zakaria ; Lock-Hock Ngu ; Wee-Teik Keng
The Malaysian Journal of Pathology 2017;39(2):99-106
Fragile X syndrome (FXS) is a neurodevelopmental disorder commonly found worldwide, caused
by the silencing of fragile X mental retardation 1 (FMR1) gene on the X-chromosome. Most of the
patients lost FMR1 function due to an expansion of cytosine-guanine-guanine (CGG) repeat at the
5’ untranslated region (5’UTR) of the gene. The purpose of this study is to identify the prevalence of
FXS and characterize the FMR1 gene CGG repeats distribution among children with developmental
disability in Malaysia. Genomic DNA of 2201 samples from different ethnicities (Malays, Chinese,
Indian and others) of both genders were PCR-amplified from peripheral blood leukocytes based on
specific primers at 5’UTR of FMR1 gene. Full mutations and mosaics were successfully identified
by triple methylation specific PCR (ms-PCR) and subsequently verified with FragilEase kit. The
findings revealed for the first time the prevalence of FXS full mutation in children with developmental
disability in Malaysia was 3.5%, a slightly higher figure as compared to other countries. Molecular
investigation also identified 0.2% and 0.4% probands have permutation and intermediate alleles,
respectively. The CGG repeats length observation showed 95% of patients had normal alleles within
11 to 44 CGG repeats; with 29 repeats found most common among Malays and Indians while 28
repeats were most common among Chinese. In conclusion, this is the first report of prevalence and
characterisation of CGG repeats that reflects genetic variability among Malaysian ethnic grouping.