Genetic Disorder of BSN 2nd professional

This ppt covers whole content of genetic disorders that are included in BSN 2nd year

1. Genetic Disorder
Sabrina Javed
ION-WMC
Date

2. Objectives
•By the end of lecture learner will be able to
understand
•Differentiate between genetic and congenital disorder
•Define trisomy, Monosomy, polysomy.
•Discuss Chromosomal defect with special emphasis
on enulpoidy .
•Discuss Down syndrome its pathophysiology and
clinical manifestation .
•Discuss Turner syndrome its pathophysiology and
clinical manifestation .
•Discuss Klinfenter syndrome its pathophysiology and
clinical manifestation .

3. The DNA molecule
•Composed of 2
polymers of
nucleotides
•Polymers are
oriented in
antiparallel
•Molecule resembles a
spiral staircase of
complementary base
pairs

4. Nucleotide structure of DNA
•Each nucleotide of
DNA contains:
–Deoxyribose
–Phosphate
–Nitrogen base (either
A, G, C, T)

5. Nucleotide structure of RNA
•Each nucleotide of
RNA contains:
–Ribose
–Phosphate
–Nitrogen base (either
A, G, C, U*)

*contains Uracil
instead of Thymine

6. DNA structure
•“Double helix”
propsed by Watson
and Crick (1953)
•Antiparallel
backbones
•Complementary
base pairing:
–Adenine to Thymine
–Cytosine to Guanine

7. DNA structure

8. Chromosomes vs Genes
•A chromosome
constitutes an entire
DNA molecule +
protein
–Protein = histones
–Supercoiled DNA in
nucleosomes
–Humans contain 46
such molecules (23
pairs)
•44 somatic chromosomes
•2 sex chromosomes (X
+Y)

9. Chromosomes vs Genes
•Genes constitute
distinct regions on the
chromosome
•Each gene codes for a
protein product
•DNA -> RNA-> protein
•Differences in proteins
brings about
differences between
individuals and
species

10. Introduction to Genetics
•GENETICS – branch of biology that deals with heredity and
variation of organisms.

•Chromosomes carry the hereditary information (genes)
•Arrangement of nucleotides in DNA
•DNA  RNA  Proteins

11. •Chromosomes (and genes) occur
in pairs
Homologous Chromosomes
•New combinations of genes occur
in sexual reproduction
–Fertilization from two parents

12. Genetics terms
•Gene – a unit of heredity;
a section of DNA sequence
encoding a single protein
•Genome – the entire set
of genes in an organism

•Alleles – two genes that occupy the same position
on homologous chromosomes and that cover the
same trait (like ‘flavors’ of a trait).
•Locus – a fixed location on a strand of DNA where a
gene or one of its alleles is located.

13. •HOMOZYGOUS ("homo" means
"the same").
• having identical genes (one from each
parent) for a particular characteristic.
•Heterozygous –("hetero" means
"other")
• having two different genes for a
particular characteristic.

16. •Dominant – the allele of a gene
that masks or suppresses the
expression of an alternate allele; the
trait appears in the heterozygous
condition.
•Recessive – an allele that is
masked by a dominant allele; does
not appear in the heterozygous
condition, only in homozygous.

19. Heredity Vs Congenital

20. Trisomy
•A trisomy is a chromosomal disorder
characterised by an additional
chromosome, so the person has 47
instead of 46.
Examples
•Down syndrome, Edward syndrome and
Patau syndrome are the most common
forms of trisomy.

21. Monosomy
•Lack of one chromosome
Turner syndrome

24. Polysomy
•Polysomy, or the presence of more
than two chromosomes to a set,
occurs when a germ cell
containing more than 23
chromosomes is involved in
conception.
•polysomy with three chromosomes
is called a trisomy, a polysomy
with four chromosomes is
called tetrasomy, etc

25. effects of Polysomy X as
seen in Klinefelter
syndrome

26. Down Syndrome
•First described in 1866 by John
Langdon
•Down, trisomy 21, or Down syndrome,
causes a combination of birth defects
including some degree of intellectual
disability, characteristic facial features,
and other health problems.
•It is the most common chromosomal
disorder.

27. Causes
•Approximately 95% of cases of
Down syndrome are caused by non
disjunction or an error in cell division
during meiosis, resulting in a trisomy
of chromosome 21.

28. •The risk of having a child with Down
syndrome increases with maternal
age.
•The reason for the correlation
between maternal age and
nondisjunction is unknown,

29. 29
Types of Down Syndrome
Types of Down Syndrome
–Trisomy 21 (95%)
•Three chromosomes 21 in every cell
–Translocation (3-5%)
•Extra part of chromosome 21 attaches to
another chromosome in every cell
–Mosaic 1-2 %
•Mixture of cells, some with an extra
chromosome 21 and others with just two.

30. Increased Medical Problems
•Most significant features – for medical care and
management
–Cardiac
–Growth
–Thyroid disorders - Diabetes
–Gastrointestinal Tract
–Hearing impairment
–Visual impairment
–Orthopaedic -CERVICAL SPINE INSTABILITY
–Sleep Obstructive Apnoea
–Speech and Language
–Epilepsy
–Leukaemia
–Klinefelter syndrome
–Alzheimer’s Disease

33. Clinical Features
•There is a flatfacial profile, with a small nose and
somewhat depressed nasal
bridge;
•small folds on the inner corners of the eyes
(epicanthalfolds) and upward slanting of the eyes;
small, low-set,
•malformed ears
• a fat pad at the back of the neck
• an open mouth; and a large, protruding tongue
•The child’s hands usually are short and stubby, with
fingers that curl inward, and there usually is only a
single palmar (i.e., simian) crease.
•There is excessive space between the large and
second toes.
• Hypotonia and joint laxity also are present in infants
and young children.
•There often are accompanying congenital
heart defects and an increased risk of gastrointestinal
malformations.

34. Diagnosis
•There are several prenatal screening tests that
can be done to determine the risk of having a
child with Down syndrome.
•The most commonly used are blood tests that
measure maternal
•serum levels of α-fetoprotein (AFP),
•human chorionic gonadotropin (hCG),
unconjugated estriol, inhibin A, and
•pregnancy-associated plasma protein A
(PAPP-A)

35. •Nuchal translucency (sonolucent
space on the back of the fetal neck) is
another test that can be done to
assess this aspect of the fetus uses
ultrasonography and can be performed
between 10 and 13 weeks’
gestation.18

36. •The fetus with Down syndrome tends to
have a greater area of translucency
compared with a chromosomally normal
infant.

37. •Down syndrome in the fetus is through
•chromosome analysis using chorionic
villus sampling, amniocentesis,
•percutaneous umbilical blood sampling,

39. Management in DS
•Provide Accurate information
•Breaking the news/diagnosis
–Say this in a positive way
•Remember Your first words to a family
have a Lifelong Impact
•Be the first step on the ladder to help
them achieve the positive adjustments
needed in their lives Focus on what can
be done

40. How You can Help
•Always use the child’s name
•Look at Mam and Dad when
communicating
•Empathy - Try to understand what it
means to have a child with Down
syndrome or any disability
•Listen to and learn from parents

41. •Individuels
–Dignity
–Inclusion
–Normalisation
–Self-determination
–Quality of Life
•Families
–The family is the base of integration
–The needs of the family itself need to be met

Rights of People with
Disabilities

42. People with DS can Achieve
•Walk/Dance/Skate
•Talk/Read/Write
•Ride a bicycle
•Photography
•Swimming/Horse riding
•Gymnastics
•Computers
•Work
•Marry/have partner

43. References
• Sheila & Carol Matson Porth
Pathophysiology ed 9
th

•Clinical/Research Nurse
Specialist/Lecturer Department of
Paediatrics /TCD