X-linked diseases are caused by mutations on the X chromosome. There are two main types: X-linked dominant and X-linked recessive diseases. X-linked dominant diseases affect both males and females and are passed from father to all daughters. X-linked recessive diseases mainly affect males and a carrier mother will pass the disease to all sons. Common X-linked diseases include color blindness, hemophilia, and Duchenne muscular dystrophy. While there are some treatment options, prevention through not having children or prenatal gene therapy may be the best approach for inherited X-linked conditions.

1. X-LINKED DISEASES

2.  Chromosome
 DNA (hereditary particle)
 Protein
Human cell has 46 chromosomes(23 pairs)

3. Gene (DNA sequence)
mRNA
Proteins (causes traits)
Genes on DNA of chromosome encode traits

4. 1. X chromosome has 2000 genes.
2. X-linked Disease: Disease caused
by mutation of gene on X
chromosome.
Sex chromosome(1 heterozygous pair XY)
Chromosome
Autosome(22 homozygous pairs)

5. X-linked disease
X-linked dominant disease
X-linked recessive disease
X-linked dominant disease: causes disease when being homozygous
and heterozygous of affected mutant chromosome.
1. Appear in same proportion in male and female.
2. One X chromosome having mutation can cause disease.
3. Female both homozygous and heterozygous for mutant X-
chromosome are affected.
4.All daughters of affected father.

6. Inheritance of X-linked dominant disease:

7. Some X-linked dominant diseases:
1. X-linked hypophosphatemia: is an X-linked dominant
form of rickets (or osteomalacia ). It can cause bone
deformity including short stature. It is associated with a
mutation in the PHEX gene.
An osteotomy may be performed to correct the leg

8. 2. Rett syndrome: is a rare genetic postnatal neurological disorder of
the grey matter of the brain.
3. Alport syndrome: is a genetic disorder affecting around 1 in
50,000 children characterized by end-stage kidney disease, and
loss.
4. Incontinentia pigmenti: is a genetic disorder that affects the skin,
hair, teeth, nails, and central nervous system. It is named due to its
microscopic appearance.

9. Prognosis:
1.As genetic disease, these diseases are less curable.
2.Osteotomy(hypophosphatemia),occupational
syndrome) etc. can be performed to recover deform
structures and parts.
3.Can be prevented by affected person not having
with affected but it can’t be stricked as being parent is a
sensitive issue.

10. X-linked recessive diseases: causes disease when only
homozygous of mutant chromosome.
1.cause disease in male in more proportion than female.
2.needed 2 mutant X chromosome to cause disease.
2.heterozygous female are carrier of these disease.
3.all sons of a affected mother are affected.
4.in some diseases heterozygous show some degree of disease
because of differences in X chromosome inactivation.
5.more common than X-linked dominant diseases.

11. Inheritance of X-linked recessive diseases:

12. Some X-linked recessive diseases:
1. Color blindness: is the decreased ability to see color
or differences in color. The most common cause of
color blindness is due to a fault in the development of
one or more of the three sets of color sensing cones
the eye.

13. 2. Haemophilia A: Haemophilia A is a genetic deficiency
in clotting factor VIII, which causes increased bleeding
and usually affects males. In terms of the symptoms of
Hemophilia A there are internal or external bleeding
episodes.
3. Haemophilia B: is a blood clotting disorder caused by
a mutation of the factor IX gene, leading to a deficiency
of factor IX. It is the second-most common form of
haemophilia, rarer than haemophilia A. The condition is
marked by increased clotting time(3-8 minutes) and
bleeding time(2-5 minutes).

14. 4. Duchenne muscular dystrophy: Duchenne
muscular dystrophy (DMD) is an X-linked recessive
form of muscular dystrophy, affecting around 1 in
3,600 boys, which results in muscle degeneration and
premature death. The disorder is caused by a
mutation in the gene dystrophin.
5. Glucose-6-phosphate dehydrogenase deficiency: s
an X-linked recessive inborn error of metabolism that
predisposes to hemolysis. Causes
jaundice in response to a number of triggers, such
certain foods, illness, or medication.

15. Prognosis:
1.As genetic disease , these diseases are less curable.
2. Lenses(Color Blindness), regular supplementation with
recombinant or plasma concentrate Factor VIII(Hemophilia A),
intravenous infusion of factor IX( Hemophilia B) etc. can be taken.
3.There no permanent cure of these disease.
4.Can be prevented by affected person or carrier not having
offspring but it can’t be strict as being parent is a sensitive issue.
5.Gene therapy at prenatal stage is an upcoming solution.

16. G
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17. 1. Awareness about these diseases must spread among
people.
2. If possible , should avoid taking offspring. Adoption
and others possible ways can be taken to have children.
3. Possible cure of diseases available should be taken.
4. Gene therapy at prenatal state can be used and can be
a great cure.
5. Research on gene therapy should be widespread.
Conclusion

18. Thank you.