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Indian Pediatr 2012;49:
799-804 |
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Spectrum of Lysosomal Storage Disorders at a
Medical Genetics Center in Northern India
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Prashant K Verma, *Prajnya Ranganath, #Ashwin
B Dalal and Shubha R Phadke
From the Department of Medical Genetics, Sanjay Gandhi Postgraduate
Institute of Medical Sciences, Lucknow;
*Department of Medical Genetics, Nizams Institute of Medical Sciences,
Hyderabad, and #Diagnostics Division,
Centre for DNA Fingerprinting and Diagnostics, Hyderabad; India.
Correspondence to: Dr Shubha R Phadke, Professor and Head, Department
of Medical Genetics, Sanjay Gandhi Postgraduate Institute of Medical
Sciences, Rae Bareilly Road, Lucknow 226 014, Uttar Pradesh, India.
Email:
[email protected]
Received: July 07, 2011;
Initial review: August 03, 2011;
Accepted: January 05, 2012.
Published online: 2012, March 30.
PII:S097475591100585-1
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Background: There is limited literature available on the phenotypic
and mutation spectrum of Indian patients with Lysosomal storage
disorders (LSD).
Objective: To elucidate the clinical, biochemical
and mutation spectrum and to study the management options in Indian
patients with lysosomal storage disorders.
Design: Descriptive study.
Subjects and Methods: All patients with lysosomal
storage disorders diagnosed in the Medical Genetics department of a
tertiary care institute in North India over a three year period from
January 2008 to December 2010.
Results: Out of the total of 93 patients
clinically suspected to have LSDs, 68 (mean age at presentation 4.5
years) were confirmed to have LSDs based on the laboratory/neuroimaging
findings and documentation of deficient enzymatic activity in the
peripheral blood (leucocytes or plasma) and/or skin fibroblasts. The
commonest clinical features at presentation were growth retardation
(failure to thrive 47.2% and short stature 17.6%), hepatosplenomegaly
(41.2%) and neuroregression (33.8%). A history of consanguinity was
present in 32.4% of the families. Prenatal diagnosis was done in a total
of 6 affected families; two pregnancies were found to be affected (one
each with Gaucher disease and Tay Sachs disease) and in both cases the
parents opted for termination of pregnancy. Of the remaining four
pregnancies which were found to be unaffected and therefore continued,
three were confirmed to be normal on post-natal follow up. Enzyme
replacement therapy (ERT) is being given for a total of 8 LSD patients
and all of them are showing a gradual amelioration of their symptoms and
an improvement in the quality of life.
Conclusions: Lysosomal storage disorders
constitute an important group of genetic metabolic disorders for many of
which therapeutic options are now available.
Key words: Lysosomal storage disorders, India, Clinical
features, Management, Mutation analysis.
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L ysosomal storage disorders
(LSDs) are a group of inborn errors of metabolism (IEM) characterized by
the intra-lysosomal accumulation of complex macro-molecules. LSDs
usually occur due to deficiencies of these lysosomal enzymes but can
also result from defects in key lysosomal membrane proteins, proteins
involved in lysosomal enzyme trafficking or lysosomal enzyme activator
proteins [1]. Almost fifty different LSDs are known at present and
although each disorder is rare, as a group LSDs have a frequency of
around 1 in 5000 live births worldwide [2].
There are only a few studies available regarding the
clinical features and mutation spectrum, use of enzyme therapy and
antenatal diagnosis in Indian patients with LSDs [3-6]. This study aims
to address this gap in knowledge.
Methods
The study was a descriptive study done over a 3-year
period from January 2008 to December 2010, in the Medical Genetics
department of a tertiary care, referral hospital in North India. All
patients diagnosed to have lysosomal storage disorders on the basis of
their clinical features and laboratory findings and confirmed through
enzyme analysis were included in the study. The relevant clinical,
biochemical, imaging and molecular genetic data and the management/
intervention details were collected for each patient. Clinical
observations noted included a complete medical history of the patient, a
detailed family history, a three generation pedigree, and a full
physical examination comprising general as well as systemic examination.
The details of the baseline laboratory investigations and enzyme
analysis results were also noted. Enzyme assay was done in the
peripheral blood sample (leucocytes or plasma) and in addition, in two
patients with Gaucher disease and one patient with Pompe disease, enzyme
assay was repeated in skin fibroblasts for confirmation because of
equivocal results in the blood assay. Enzyme analysis was done from
standard diagnostic laboratories, as per recommendations [7]. Mutation
reports, where available, were recorded (blood samples for molecular
genetic studies for the different LSDs were sent to different national
and international research groups, who used the whole gene sequencing
technique for identifying the mutations). The collected data was
statistically analyzed.
Results
Ninety three patients were suspected to have LSDs on
the basis of their clinical features during the 3-year study period; out
of these, 68 (76.4% males) patients were confirmed to have different
types of LSDs, seven were lost to follow up and did not undergo the
necessary enzyme assays for confirmation of the clinical diagnosis and
in the remaining 18, the enzyme assay results were normal. The age at
presentation of the LSD patients varied from 5 months to 26 years (with
the exception of one MPS I case which presented as non-immune hydrops
fetalis at 26 weeks gestation), with an average age of 4.5 years.
Consanguinity was present in 22 families (32.4%). Thirty patients
(44.1%) had history of one or more siblings with similar clinical
features, but except in four cases, the diagnosis had not previously
been established in the similarly affected siblings.
The diagnosis made and the enzyme activity levels in
patients with LSDs are shown in Table I. Most of the
patients had enzyme activity levels between 0 to less than 10% of the
normal reference range of the respective enzyme. The pathogenic genetic
mutation could be identified in only 7 families. Hurler (type I MPS) and
Hunter (type II MPS) syndromes accounted for 78.2% of the MPS group. One
case of MPS I was incidentally diagnosed through fetal autopsy; this
fetus had died in-utero at 26 weeks gestation due to non-immune
hydrops fetalis and MPS I enzyme ( b-iduronidase)
assay done in cord blood as a part of the work-up for non-immune fetal
hydrops revealed very low levels of the enzyme (0.2 nmol/ h/ mg;
reference range 22-56 nmol/h/ mg) against normal values of the control
enzyme (b-galactosidase
110 nmol/h/mg; reference range 70-324 nmol/h/mg), thereby leading to the
diagnosis. Out of the ten cases of Gaucher disease, eight had the type I
non-neuronopathic form, one had the type II acute neuronopathic form and
one had the type III sub-acute neuronopathic form.
TABLE I Patients with the Different Types of LSDs (N=68)
Type of LSD |
No. |
Blood enzyme levels (range)
(nmol/ h/ mg) |
Mutations identified in the causative
gene |
MPS I |
9 |
0.4-5.2 |
|
MPS II |
9 |
0.4-4.9 |
|
MPS IVA |
4 |
0.6-1.6 |
|
MPS VI |
1 |
0.6 |
|
Gaucher disease
|
10 |
0.38-3 (Skin fibroblast: 10 - 21) |
GBA gene: S237F/R496C; S356F/ |
|
|
|
S356F; L444P/L444P
|
Metachromatic leukodystrophy |
10 |
1.5-18 nmol/ 17h/ mg |
|
GM1 gangliosidosis*
|
6 |
0.64 - 4.2
|
|
Tay-Sachs disease |
4 |
0.5 - 1.3 |
HEXA gene: 1277_ 1278insTATC/
|
|
|
|
1277_1278insTATC
|
Pompe disease |
3 |
2.4 - 5.6 (Skin fibroblast: 3) |
GAA gene:D489N/ R600H; E655del/ |
|
|
|
D489N
|
Sandhoff disease
|
3 |
54-149 |
|
Niemann-Pick disease |
3 |
0.57-1.2 nmol/ 17h/ mg |
|
Fabry disease
|
2 |
0.1- 0.02
|
GLA gene: W236X |
Mucolipidosis III
|
2 |
Hexosaminidase A+B: ~ 20,000 -
|
|
|
|
28,000 |
Iduronate sulphate sulphatase:
|
|
|
560-730 |
|
Neuronal ceroid lipofuscinosis
|
1 |
10
|
|
Wolman disease |
1 |
0.0
|
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The most common reasons for referral were
visceromegaly (particularly hepatosplenomegaly, 41.2%) and
neuroregression (33.8%). The common findings were growth retardation
(failure to thrive 47.2%; short stature 17.6%), dysostosis multiplex
(41.1%), joint contractures (36.7%) and coarse facies (36.7%). Extensive
Mongolian spots over the trunk, back and extremities found in many
children with the infantile onset GM1 gangliosidosis were noted in four
of our six patients with this condition. Apart from neuroregression,
other neurological features noted were hypotonia (8.8 %) and progressive
ataxia and dysarthria (5.9%). Of the two male sibs with Fabry disease,
the elder sib presented with acute episodes of severe pain and
paraesthesias in the extremities and the other had recurrent diarrhea;
the elder sib had received several courses of non-steroidal
anti-inflammatory drugs and due to the non-specificity of his symptoms,
had even been thought to have a psychiatric disorder. The
child with Wolman disease presented with a history
of recurrent episodes of loose stools starting from around 4 to 5 months
of age with severe failure to thrive and the diagnosis was suspected
after his abdominal ultrasonography revealed bilateral homogenous
calcification of the adrenal glands.
Prenatal diagnosis was done for 6 families (2 of
Pompe disease and 1 each of Gaucher disease, MPS I, MLD and Tay Sachs
disease) after appropriate genetic counseling and with the informed
consent of the couples. The method used for prenatal diagnosis was
enzyme assay in the chorionic villus sample (CVS), taken at around 11-12
weeks of gestation (enzyme assay was done directly in the obtained CVS
sample without any prior culturing). In addition, targeted mutation
analysis in the CVS DNA, based on the mutations identified in the
proband, was done in 3 families (2 with Pompe disease and 1 with
Tay-Sachs disease) for further confirmation. The results of the prenatal
diagnostic tests are mentioned in Table II. Two
pregnancies were found to be affected (one with Gaucher disease and one
with Tay-Sachs disease) and in both cases the parents opted for
termination of pregnancy. The remaining four pregnancies that were found
to be unaffected were continued; three were confirmed to be normal on
postnatal follow up and 1 was lost to follow up.
TABLE II Results of the Prenatal Diagnostic Tests in Six Families with Lysosomal Storage Disorders
Type of LSD in proband
|
CVS enzyme valuein nmol/h/mg |
Targeted mutation
|
Interpretation
|
(enzyme assay done) |
(Normal reference range of laboratory) |
analysis |
(affected/ not affected)
|
Gaucher disease (β-glucosidase) |
0 (250-782) |
Not done |
Affected
|
Metachromatic leukodystrophy |
31 nmol/ 17 h/ mg |
Not done |
Not
|
(Arylsulphatase A)* |
(25 80 nmol/17 h/mg) |
|
affected
|
Mucopolysaccharidosis I
|
187 (110-226) |
Not done |
Not affected |
(αiduronidase)$ |
|
|
|
Pompe disease (family 1) |
Lab I: 26 (101-305) |
No mutations in GAA gene
|
Not affected |
(α-glucosidase)# |
Lab II: 60 (140-280) |
|
|
Pompe disease (family 2) |
Lab I: 13.3 (132-525) |
Heterozygous carrier of
|
Not affected |
(α-glucosidase) |
Lab II: 56 (140-280) |
1 mutation (c.1962_1964
|
|
|
|
delAGA) in GAA gene |
|
Tay Sachs disease |
108 (1560-3100) |
Homozygous for 1277_1278 |
Affected
|
(Hexosaminidase A) |
|
insTATC mutation in HEXA gene |
|
* Blood leucocyte arylsulphatase A assay at 5 months after
birth: 78 nmol/ h/ mg (reference range 67 396 nmol/ 17 hr/
mg); $ Lost to follow up; # Blood leucocyte a-glucosidase assay
at 3 months after birth: 100 nmol/ h/ mg (reference range 86
296 nmol/ h/ mg); Child normal on clinical evaluation at 10
months of age. |
Enzyme replacement therapy (ERT) was initiated for 8
patients, four with type I Gaucher disease, 3 with MPS type I H/S
(Hurler Schie) and 1 with Fabry disease. All of them showed a gradual
amelioration of their symptoms. The four patients with non-neuronopathic
Gaucher disease on ERT showed improvement of their growth and
hematological parameters and reduction of liver and spleen size. The
three patients with MPS I H/S on ERT showed a reduction of liver and
spleen size, improvement in growth parameters and 6-minute walk test,
and a mild improvement in their joint mobility. There has been no change
noted in the corneal opacity, facial coarseness or dysostosis. The
patient with Fabry disease had a significant reduction of limb pain and
paraesthesias and improvement in height and weight after initiation of
ERT. He had hypersensitivity reactions during three successive infusions
in the third year of his ERT, which probably occurred in response to
some allergen present in one particular batch of recombinant enzyme.
Discussion
The age of presentation and clinical manifestations
of LSDs depend on the substrates accumulated, the rate and the magnitude
of their intracellular accumulation, the percentage of residual
functional enzyme and presence of alternative functional pathways [8,9].
In the present study, we detected one case of
mucopolysaccharidosis type I in the antenatal period in a fetus with
non-immune fetal hydrops.
The most common causes of morbidity and mortality in
LSDs are due to neurological, visceral, cardiovascular and skeletal
involvement, which were observed in our patients also [3]. Apart from
the mucopolysaccharidoses, the skeletal changes of dysostosis multiplex
are also seen in GM1 gangliosidosis and various oligosaccharidoses [10].
The present study had five patients of oligosaccharidoses and GM1
gangliosidosis who presented with an MPS-like picture and were
differentiated based on the absence of urinary glycosaminoglycans.
In Pompe disease, alpha-glucosidase enzyme assay in
leucocytes may give falsely normal results due to the presence of
isoenzymes such as maltase-glucoamylase in the blood, as happened in one
of our cases with Pompe disease; therefore, conventionally, enzyme assay
in skin fibroblasts or in the muscle tissue is considered to be more
reliable. However, modifications in the blood leucocyte alpha-glucosidase
assay protocol have now made enzyme assay in blood samples reliable
[11].
Non-specific symptoms and lack of definite physical
findings often lead to misdiagnosis of Fabry disease cases as gout or
other rheumatological disorders or malingering, as happened in our
patient. The diagnosis must be kept in mind in any patient with
suggestive features. This is especially important as effective enzyme
replacement therapy (ERT) is now available for Fabry disease and early
and timely institution of ERT can prevent/ ameliorate the renal and
cardiovascular complications of the disease [12].
A complete ophthalmological evaluation including slit
lamp and fundus examination and electroretinogram studies, where
required, can provide important clues for the diagnosis of lysosomal
storage disorders [13]. Bilateral fundal cherry red spots were detected
in all of the four Tay-Sachs cases, 2 out of the three Sandhoff cases
and in 2 of the three GM1 gangliosidosis patients who underwent a fundus
examination.
Accurate diagnosis of the type of LSD is imperative
not only for appropriate management of the affected child, but also for
prenatal diagnosis for future pregnancies in the family. Prenatal
diagnosis is conventionally being done through enzyme assay in the
chorionic villus sample or cultured amniocytes [14,15]. However, enzyme
assay results can be erroneous at times due to problems related to
technical expertise, sample transportation and maternal contamination.
If the causative pathogenic mutations are
identified in the proband or in the carrier parents, targeted mutation
analysis in the fetal DNA can also help determine if the fetus is
affected. Combining molecular genetic testing with enzyme assay has been
found to significantly increase the reliability of the prenatal
diagnostic procedure [16]. The main limitations with molecular genetic
testing are the limited availability of centers for such testing and the
cost. In the present study, there were two families with Pompe disease,
where targeted mutation analysis in the chorionic villus sample DNA had
to be done for prenatal diagnosis, as the enzyme assay results were
equivocal and inconclusive. Targeted mutation analysis was also done for
confirmation of the enzyme assay results for prenatal diagnosis of
Tay-Sachs disease in one family.
Mutations were identified in 7 families with LSDs. Of
the three families with Gaucher disease in whom the mutations were
identified, only 1 family had one of the common mutations in the GBA
gene (L444P/ L444P) reported in Ashkenazi Jewish and other Caucasian
populations [17]. The
mutation found in the HEXA gene in our Tay-Sachs disease patient
(+TATC1278) is the same mutation that has been reported to be found in
around 70% of carriers of Tay-Sachs disease in the Ashkenazi Jewish
population [18].
ERT is currently available for six LSDs (Gaucher
disease, Pompe disease, Fabry disease and mucopolysaccharidoses types I,
II and VI) [19]. Regular intravenous infusions of the recombinant enzyme
have been demonstrated to be safe and effective in reversing the
features resulting from hematologic and visceral involvement, in
reducing bone pain and the frequency of bone crises, and in
significantly improving the quality of life in Gaucher disease [20]. ERT
for MPS disorders (types I, II and VI) has been shown to produce
significant improvement in pulmonary function and the six-minute walk
test performance, reduce urinary glycosamino-glycan excretion, reduce
the liver and spleen volume, improve growth and joint mobility and
decrease sleep apnea [21]. Similar improvement has been noted in our
Gaucher and MPS I H/S patients on ERT. However, the currently available
forms of ERT do not have any effect on the neurological features of the
LSDs, as they cannot cross the blood-brain barrier [19].
Though exact prevalence studies are not available for
the Indian population, lysosomal storage disorders as a group are not
uncommon. The present study gives us an insight into the clinical and
biochemical spectrum of Indian patients with LSDs. There is a need to
increase awareness about these disorders in the medical community to
ensure accurate diagnosis and appropriate management of the affected
patients as well as appropriate genetic counseling and prenatal
diagnosis for their families.
Acknowledgments: We thank the Indian Council of
Medical Research for providing support for the DNA banking of the LSD
patients and Genzyme Corporation, USA for providing ERT for our patients
through the "International Charitable Access Programme". We also thank
Dr Pramod Mistry (Yale School of Medicine, New Haven), Dr Deeksha Bali
and Dr Priya Kishnani (Duke University, Durham), Dr Robert Desnick
(Mount Sinai Medical Centre, New York) and Dr Parag Mohan Tamhankar
(Genetics Research Centre, Mumbai) for their help in the mutation
analysis of Gaucher, Pompe, Fabry and Tay-Sachs disease patients,
respectively.
Contributors: PKV collected the data and helped
in the drafting of the paper, PR analysed the data and drafted the
manuscript, ABD helped in performing and interpreting the tests and SRP
conceived and designed the study and revised the manuscript for
important intellectual content. The final manuscript was approved by all
authors.
Funding: None; Competing interests:
None stated.
What is Already Known?
Lysosomal storage disorders, are fairly
common genetic disorders which present with multi-organ
involvement including neuro-degeneration and visceromegaly.
What This Study Adds?
Considering the possibility of LSDs in
patients with the relevant clinical and laboratory findings and
confirming the diagnosis through appropriate enzyme assays helps
in the appropriate management of these patients and in providing
correct genetic counseling and prenatal diagnosis for their
families.
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References
1. Lysosomal disorders. In: Scriver CR,
Beaudet AL, Sly WS, Valle D, Childs B, Kindler KW, et al,
editors. The Metabolic and Molecular Bases of Inherited Disease. 8th ed.
New York; McGraw-Hill, 2001. p. 3371-877.
2. Miekle PJ, Hopwood JJ, Clague AE, Carey WF.
Prevalence of lysosomal storage disorders. J Am Med Assoc.
1999;281:249-54.
3. Sheth J, Patel P, Sheth F, Shah R. Lysosomal
storage disorders. Indian Pediatr. 2004;41: 260-5.
4. Sheth JJ, Sheth FJ, Oza NJ, Gambhir PS, Dave UP,
Shah RC. Plasma chitotriosidase activity in children with lysosomal
storage disorders. Indian J Pediatr. 2010;77:203-5.
5. Shukla P, Vasisht S, Srivastava R, Gupta N, Ghosh
M, Kumar M, et al. Molecular and structural analysis of
metachromatic leukodystrophy patients in Indian population. J Neurol
Sci. 2011;301:38-45.
6. Nagral A, Mewawalla P, Jagadeesh S, Kabra M,
Phadke SR, Verma IC, et al. Recombinant macrophage targeted
enzyme replacement therapy for Gaucher disease in India. Indian Pediatr.
2011;48:779-84.
7. Filocamo M, Morrone A. Lysosomal storage
disorders: molecular basis and laboratory testing. Hum Genomics.
2011;5:156-69.
8. Beck M. Variable clinical presentation in
lysosomal storage disorders. J Inherit Metab Dis. 2001;24:7-51.
9. Burin MG, Scholz AP, Gus R, Sanseverino MV, Fritsh
A, Magalhaes JA, et al. Investigation of lysosomal storage
diseases in non-immune hydrops fetalis. Prenat Diagn. 2004; 24:653-7.
10. Robinson C, Baker N, Noble J, King A, David G,
Sillence D, et al. The osteodystrophy of Mucolipidosis type III
and the effects of intravenous pamidronate treatment. J Inherit Metab
Dis. 2002;25:681.
11. Pompe Disease Diagnostic Working Group,
Winchester B, Bali D, Bodamer OA, Caillaud C, Christensen E, Cooper A,
et al. Methods for a prompt and reliable laboratory diagnosis of
Pompe disease: Report from an International Consensus Meeting. Mol Genet
Metab. 2008;93:275-81.
12. Phadke SR, Mandal K, Girisha KM. Fabry disease: a
treatable lysosomal storage disorder. Natl Med J India. 2009;22:20-2.
13. Wraith JE. The clinical presentation of lysosomal
storage disorders. Acta Neurol Taiwan. 2004;13:101-6.
14. Wang RY, Bodamer OA, Watson MS, Wilcox WR.
Lysosomal storage diseases: Diagnostic confirmation and management of
presymptomatic individuals. Genet Med. 2011;13: 457-84.
15. Carey WF, Hopwood JJ, Poulos A, Petersons D,
Nelson PV, Muller V, et al. Prenatal diagnosis of lysosomal
storage diseases. Review of experience in 145 patient referrals over a
period of eight years. Med J Aust. 1984;140:203-8.
16. Kishnani PS, Steiner RD, Bali D, Berger K, Byrne
BJ, Case L, et al. Pompe disease diagnosis and management
guideline. Genet Med. 2006;8:267-88.
17. Beutler E, Gelbart T, Kuhl W, Zimran A, West C.
Mutations in Jewish patients with Gaucher disease. Blood.
1992;79:1662.
18. Myerowitz R, Costigan FC. The major defect in
Ashkenazi Jews with Tay-Sachs disease is an insertion in the gene for
the alpha-chain of beta-hexosaminidase. J Biol Chem. 1988;263:18587-9.
19. Muro S. New biotechnological and nanomedicine
strategies for treatment of lysosomal storage disorders. Wiley
Interdiscip Rev of Nanomed Nanobiotechnol. 2010;2:189-204.
20. Pastores GM, Hughes DA. Gaucher Disease. In:
GeneReviews at GeneTests: Medical Genetics Information Resource
[database online]. Pagon RA, Bird TD, Dolan CR, Stephens K, editors.
2000 Jul 27 [updated 2011 Feb 01]. Available at www.genetests.org.
Accessed on May 16, 2011.
21. Clarke LA. Mucopolysaccharidosis type I. In:
GeneReviews at GeneTests: Medical Genetics Information Resource
[database online]. Pagon RA, Bird TD, Dolan CR, Stephens K, editors.
2002 Oct 31 [updated 2007 Sep 21]. Available at www.genetests.org.
Accessed on May 16, 2011.
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