Genetic Disorders due to Error in Meiosis

1. Prepared by:
Ms. Jasmine Nikki M. Versoza

2. Humans have 22 pairs of non-sex
chromosomes known as autosomes
and one pair of sex chromosomes
XX – female
XY - male

4. When a chromosome pair doesn’t
separate during meiosis
One of the gametes might have an
extra chromosome number and
others might have few

5. Having an abnormal chromosome
number
In human cell, instead of 46
chromosomes in each cell, it might
have 45 or 47.

6. Prepared by:
Ms. Jasmine Nikki M. Versoza

7. Almost 6% of all babies are born with
some form of genetic disorder.
Worldwide, that’s about 8 million
babies every year

8. There’s an extra chromosome
Trisomy 13
Trisomy 18
Trisomy 21

9.  Patau Syndrome
 A serious rare genetic disorder caused by
having an additional copy of chromosome
13 in some or all of the body cells.
 This severely disrupts normal development
and, in many cases, results in miscarriage,
stillbirth or the baby dying shortly after birth.

10.  More than 9 out of 10 children born with
Patau's syndrome die during the first
year.
 About 1 in 10 babies with less severe
forms of the syndrome, such as partial
or mosaic trisomy 13, live for more than
a year.

12.  Severe heart
defects
 Holoprosencephaly
 Cleft lip and palate
 Microphthalmia
 Anophthalmia
 Hypotelorism
 Problems with the
development of the
nasal passages
SYMPTOMS/FACIAL FEATURES

13. Microcephaly
Cutis aplasia
Ear malformations and deafness
Raised, red birthmarks
SYMPTOMS/FACIAL FEATURES

14. Cause
 Most cases of the syndrome do not run
in families.
 They occur randomly during conception,
when the sperm and egg combine and
the fetus starts to develop.

15. Edward Syndrome
Result from having three copies of
chromosome 18 in each cell in the
body instead of the usual two copies

16.  Edwards' syndrome affects how long a baby
may survive.
 Most babies with Edwards' syndrome will die
before or shortly after being born.
 A small number, about 13 in 100, babies
born alive with Edwards' syndrome will live
past their 1st birthday.

17. Symptoms/Facial Features
 Intrauterine growth retardation
 Craniofacial features such as
abnormalities of the jaw, skull, ears, and
neck
 Clenched fists with overriding fingers
 Small fingernails

18. Symptoms/Facial Features
 Short sternum
 Club feet
 Heart defects
 Kidney defects
 Neurodevelopmental delays

19. Cause
Most cases of trisomy 18 are not
inherited, but occur as random
events during the formation of eggs
and sperm

20.  Down Syndrome
 Occurs because of the extra copy of
chromosome 21, which can cause the
body and brain to develop differently
than a child without the syndrome
 Adults with Down syndrome may live
about 60 years, but this can vary.

21. SYMPTOMS/FACIAL FEATURES
 Distinctive facial features
 Mild to moderate intellectual disabilities
 Heart, kidney and thyroid issues
 Numerous respiratory infections
 Skeletal abnormalities
 Flexible joints and weak, floppy muscles

22. SYMPTOMS/FACIAL FEATURES
Overly quiet baby
Less responsive to stimuli
Vision and hearing impairment
Inwardly curved little finger

24.  A genetic disorder wherein there’s a missing
chromosome
 Example: Turner Syndrome or Monosomy X
 The affected individual has only one X
chromosome.
 In other cases of Turner syndrome, there may
be only part of the second X chromosome
missing, or it may have a structural abnormality.

25.  Turner Syndrome
 A rare genetic disorder that occurs in girls
 The seriousness of these problems varies
from girl to girl.
 Many of the health problems affecting girls
with Turner syndrome can be managed or
fixed with treatment.

26. SYMPTOMS/FACIAL FEATURES
 Puffy hands and feet at birth
 Wide neck with folds of skin down the sides of
neck
 Short height
 A low hairline at the back of the neck
 Feeding problems as a baby
 Small differences in the shape and position of the
ears

27. SYMPTOMS/FACIAL FEATURES
 Broad chest with widely spaced nipples
 More small brown moles on the skin than normal
 Deep-set nails
 Small jaw
 Narrow top of the inside of the mouth
 Skeletal problems
 Eye problems requiring glasses

29.  https://letstalkscience.ca/educational-resources/stem-in-
context/meiosis-mistakes
 https://www.acog.org/patient-resources/faqs/pregnancy/genetic-
disorders#:~:text=A%20common%20trisomy%20is%20trisomy,
missing%20or%20damaged%20X%20chromosome.
 https://www.nhs.uk/conditions/pataus-syndrome/
 https://medlineplus.gov/genetics/condition/trisomy-
18/#resources
 https://www.stanfordchildrens.org/en/topic/default?id=down-
syndrome-trisomy-21-90-P02356
 https://www.cdc.gov/ncbddd/birthdefects/downsyndrome.html