This presentation summarizes information on 4 genetic disorders: fructose intolerance, phenylketonuria, alkaptonuria, and glycogen storage disease. It defines each disorder, explains their genetic and biochemical basis, clinical manifestations including symptoms and diagnosis, current treatment approaches, and potential future research directions. For each disorder, the presentation provides details on defective enzymes or genes involved, metabolic pathways impacted, and statistics on prevalence. It aims to enhance understanding of these inborn errors of metabolism.

1. PRESENTATION ON
GENETIC DISORDER:
FRUCTOSE INTOLERANCE
PHENYLKETONURIA
ALKAPTONURIA
&
GLYCOGEN STORAGE DISEASE
GEB 11th batch.
Department of Genetic Engineering & Biotechnology.
University of Chittagong, Bangladesh.

2. AIMS & OBJECTIVES
• Define the genetic disorders
• Understanding the genetic and biochemical basis of these disorders
• Follow up the clinical manifestation
• Evaluating the treatment and research perspective

3. HEREDITARY FRUCTOSE INTOLERANCE (HFI)
• An inborn error of fructose metabolism caused by a deficiency of the
enzyme aldolase B.
• An autosomal recessive condition
• The incidence of hereditary fructose intolerance is estimated to be 1
in 20,000 to 30,000 individuals each year worldwide.
• Not as same as fructose malabsorption or dietary fructose
intolerance.

4. GENETIC & BIOCHEMICAL BASIS OF HFI
Mutations in the ALDOB gene
cause hereditary fructose intolerance.
The ALDOB gene provides instructions for
making the aldolase b enzyme. This
enzyme is found primarily in the liver and
is responsible for the second step in the
metabolism of fructose
Lack of functional aldolase B results in an
accumulation of fructose-1-phosphate in
liver cells. This buildup is toxic, resulting in
the death of liver cells over time.

5. CLINICAL MANIFESTATION
SYMPTOMS
• Similar to those of galactosemia
(inability to use the sugar galactose).
Later symptoms relate more to liver
disease. Symptoms may include---
• Convulsions
• Excessive sleepiness
• Yellow skin or whites of the eyes
(jaundice)
• Problems after eating fruits and other
foods that contain fructose or sucrose
• Vomiting
DIAGNOSIS
 Physical examination may show:
• Enlarged liver and spleen
• Jaundice
 Tests that confirm the diagnosis include:
• Blood sugar test
• Enzyme studies
• Genetic testing
• Kidney function tests
• Liver function test

6. TREATMENT
• As it is a inborn genetic disorder the cure is still unknown.
• The normal treatment is a strict fructose free diet. This involves
exclusion of anything that contains fructose, sucrose or sorbitol.
• Sometimes glucose uptake along with fructose may increase the
efficacy of fructose metabolism.

7. FUTURE PERSPECTIVE…
• While a great deal is known about aldolase B and HFI, there is still a great deal
more to investigate. Aldolase B protein interaction networks indicate that many
interactions are only currently predictions.
• Future direction 1: comparing aldolase b protein of human to other homologs
such as mouse, drosophila etc.
• Future direction 2: identifying the significance of alanine in the low complexity
region (lcr)

8. PHENYLKETONURIA (PKU)
• Rare genetic disorder causes accumulation of PHENYLALANINE in the
body.
• Inborn error of metabolism.
• Caused by absent PHENYLALANINE HYDROXYLASE (PAH) enzyme
activity which convert PHENYLALANINE to TYROSINE.

9. GENETIC BASIS
An autosomal recessive disorder . Two
PKU alleles are required for an
individual to exhibit the symptoms.
Characterized by Homozygous or
compound Heterozygous mutation in
the gene for encoding PAH enzyme.
The gene for PAH is located on
chromosome 12 and 170 type of
mutation can be occurred of this gene.

10. BIOCHEMICAL BASIS

11. CLINICAL SIGNIFICANCE
SYMPTOMS:
• Mental retardation
• Behavioural , emotional and social
problem
• Delayed development
• Poor bone strength
• Musty odor in breath, urine and skin
DIAGNOSIS:
• PAH enzyme test.
• Phenyl lactate and phenyl pyruvate
amount test.
• Newborn screening.

12. TREATMENT
• Dietary restriction of Phenylalanine
• Tyrosine supplementation.
• Consuming large neutral amino acids. These may compete with
phenylalanine at the brain barrier and block phenylalanine entry into
brain. Such as PREKUNILS
• BH4 therapy or SAPROPTARIN DIHYDROCHLORIDE supplementation.

13. TETRAHYDRO BIOPTERIN
(BH4) THERAPY
Reconstituting PAH expression by co-expression of
BH4 biosynthetic enzymes
The BH4 cofactor, essential for PAH activity is
endogenously synthesized starting from guanosine
triphoshate (GTP)
By constitutive action of three enzymes: GTP cyclohydrolase
I (GTPCH), 6-pyruvoltetrahydrobiopterin synthase (PTPS)
and sepiapterin reductase (SR), and is maintained by
recycling dihydropteridine reductase (DHDR).
The enzymes circled in red represent alternative gene
targets for gene therapy of PKU by enhancing BH4
biosynthesis in combination with PAH activity.

14. FUTURE PROSPECT AND TREATMENT
• ENZYME REPLACEMENT THEORY:
✓ Treatment of PKU using phenylalanine ammonia lyase (PAL)
✓PAL is an enzyme substitution therapy that break down phenylalanine into ammonia and trans-cinnamic acid
✓PAL exists in bacteria and yeast; not in mammals.
✓In therapy in order to reduce its immunogenicity it is conjugated with polyethylene glycol (peg).
✓Subcutaneous administration of pal result in lowering plasma and brain phenylalanine concentrations. However the
metabolic effect was not sustained due to an immune response
✓PAL therapy is more favorable than PAH because it requires no cofactors for degrading the (phe) and its metabolites
has low toxicity levels and no embryotoxic effects. In experimental animals, the PAL was very stable under wide
range of temperatures.

15. GENE THERAPY FOR PKU
• Gene therapy is an experimental, yet very promising approach for PKU treatment.
• By delivering a functional PAH gene to the liver in vivo, its activity should be
reconstituted leading to normal clearance of phenylalanine in the blood.
• Significantly, it has been reported that reconstitution of 10-20% of normal PAH
enzymatic activity is sufficient to restore normal serum phenylalanine levels .
• Advances in PKU treatment by gene therapy has been accelerated by the
availability of pre-clinical models of disease.
• Viral vectors have had some success in phenotypic correction of the mice in vivo.
Infusion of recombinant adenoviral vectors to the liver resulted in a significant
increase in PAH activity leading to complete normalization of the serum
phenylalanine levels within one week of treatment

16. ALKAPTONURIA (AKU)
• Called BLACK URINE disease or BLACK BONE disease.
• First human inborn error of metabolism to be discovered.
• Rare Autosomal recessive disorder.
• Lack of HOMOGENTISIC OXIDASE enzyme blocks the metabolism of
HOMOGENETISIC ACID. Thus HOMOGENTISIC ACID accumulate in
the body.
• Mutations on the both copy of the HGD gene is a result of abnormal
HOMOGENTISIC OXIDASE enzyme.

17. BIOCHEMICAL BASIS:

18. PREVALENCE IN BANGLADESH:
• In 2016 a case report of KHULNA MEDICAL COLLEGE HOSPITAL indicates a male
patient of 45 years old was affected by ALKAPTONURIA disease.

19. STATISTICS
• occurs in 1 in 250000 people in the world but more common in
SLOVAKIA and DOMINIC REPUBLIC where it occurs upto 1 in 19000
people .
• The first Bangladeshi Alkaptonuria affected person was found in
2016.

20. CLINICAL SIGNIFICANCE
SYMPTOMS
• Urine become black when
exposed to air.
• Osteoarthritis
• Thickened and darkened
cartilage in ears.
• Dark spots on sclera of eyes.
DIAGNOSIS
• Urine test ( color detection)
• DNA testing
• Separation of HOMOGENTISIC
ACID traces by gas
chromotagraphy.

21. TREATMENTS:
• As it is a genetic disorder , there is no specific treatment for AKU.
• Some treatments are available to reduce the complication of AKU-
✓ low phenylalanine and tyrosine containing diet
✓ Vitamin C ( ascorbic acid) uptake.
✓ surgery for joint pain.
✓ Physical exercise.

22. FUTURE PROSPECTS &
TREATMENTS
NITISIONE:
May use as a treatment of AKU . NITISIONE is a triketone
which inhibits the enzyme HYDROXYPHENYLPYRUVATE
DIOXYGENASE responsible for converting TYROSINE to
HOMOGENTISIC ACID. Therby blocking the production and
accumulation of HOMOGENTISIC ACID.
GENE THERAPY:
Gene therapy is using widespreadly in many occurences
defining the variant enzyme of the pathway.

23. GLYCOGEN STORAGE DISEASE (GSD)
• Result of defects in the processing of glycogen synthesis or breakdown.
• In muscles, liver and other cell type.
• Two classes of cause- a) GENETIC b) ACQUIRED
• There are several types of GSD in the basis of Glycogen Metabolism.
• Statistics: in USA , 1 in per 20000-25000 birth. A dutch study estimated it
to be 1 in 40000. in England one in 43000 birth. The overall GSD
incidence is estimated 1 case per 20000-40000 live births.

24. BIOCHEMICAL PATHWAY

26. TREATMENT
• depends on the type of GSD. Some GSD Types cant be treated ,
others are fairly easy to control by treating the symptoms.
• Untreated GSD patients are prescribed to follow a special Diet.
- Frequent high carbohydrate diet.
- Medicine is sometimes prefferred cause GSD tend to cause uric acid to
build up in the body. This build up of uric acid can cause GOUT and
kidney stones.

27. FUTURE PRESPECT & NEW RESEARCH
PROTEIN THERAPY:
Cant use protein replacement treatment of GSD1-a as deficiency in G6Pase-a causes GSD type 1a and
deficiency in G6PT causes GSD type 1b. G6Pase-a G6PT are both hydrophobic and endoplasmic
reticulum associated transmembrane protein that cant expressed in active form.
INDUCING AUTOPHAGY:
• Autophagy is a process in which a damaged cell degrades into its basic components and recycles
itself for use by other cells. Impaired autophagy contributed to the pathology of GSD1-a by
disrupting fat metabolism that would otherwise aid the breakdown of fat stored in the liver. This
disruption led to high fat levels, which would eventually cause fatty liver.
• With these findings, induced autophagy in cell and animal models and saw reductions in fat and
glycogen levels. A drug commonly prescribed to prevent transplant rejection -- rapamycin --
stimulated autophagy and improved liver size and function in animal models.
• Ref: https://www.sciencedaily.com/releases/2015/11/151118131720.htm

28. REFERENCES….
• BOUTELDJA N, TIMSON DJ. THE BIOCHEMICAL BASIS OF HEREDITARY FRUCTOSE INTOLERANCE.
J INHERIT METAB DIS. 2010 APR;33(2):105-12. DOI: 10.1007/S10545-010-9053-2. EPUB 2010
FEB 17. REVIEW. CITATION ON PUBMED
• ALI, M., RELLOS, P., COX, T. M. HEREDITARY FRUCTOSE INTOLERANCE. J. MED. GENET. 35: 353-
365, 1998.[PUBMED: 9610797, RELATED CITATIONS] [FULL TEXT]
• PETER BAKER, II, MD, FAAP, FACMG, LACHLAN AYRES, MB, CHB, MRCP, SOMMER GAUGHAN, RD,
CSP, AND JAMES WEISFELD-ADAMS, MB, CHB, FAAP, FACMG. HEREDITARY FRUCTOSE
INTOLERANCE. PUBMED: DECEMBER 17, 2015.
• CHRISTINE.S.BROWN, UTA KONECKI. PHENYLKETONURIA: A PROBLEM SOLVED? MOLECULAR
GENETICS AND METABOLISM REPORT. SCIENCEDIRECT.COM
• WELCH TR. PHARMACOLOGIC APPROACH TO PKU. PEDIATRICS.JUN 2001;150(6)

29. REFERENCES….
• Pku treatment and management; author: eric t rush, md, faap, facm.
May 18 2017
• Hhtps://www.Ncbi.Nlm.Nih.Gov/pmc/articles.Pmc4146814