2. Chromosomal aberrations
Definition :-
“Any deviation either in number or structure of the
chromosomes is referred as chromosomal aberrations”
Types :-
1) Structural aberrations.
2) Numerical aberrations.
4. Numerical aberrations
Autosomal :-
Monosomies are fetal – Abortion.
Trisomies are common.
Trisomy 21 / Down’s syndrome
Trisomy 18 / Edwards syndrome
Trisomy 13 / Patau syndrome
Sex chromosome related :-
Turners syndrome / 45X
Polysomy X syndrome / e.g. XXX, XXXX
Klinfelters syndrome / 47 XXY
5. Turners syndrome
Introduction:
Monosomy X
Described by Turner in 1938
Cytogenetics – ford et al. 1959
Affects females only, 1:2500
“XO” instead of “XX”
Clinical features:
Phenotype – Female
short stature (approx.
4’8”), short neck with webbed
appearance
Cubitus valgus
6. low hairline at the back of
the neck, low set ears
Broad chest, widely spaced
nipples
High arched palate
Lymphoedema over feet
CVS: coarctation of aorta
VSD
8. Shorter than average/slow growth rate
No growth spurts during puberty
Non-functioning ovaries
No production of estrogen or progesterone
Infertility
Middle Ear infections leading to eventual loss of
hearing
Problems with math, memory skills, and fine-finger
movements
Discolored spots on skin
9. Broad chest/widely spaced nipples
Heart murmur due to narrowing of aorta
High blood pressure
Minor vision issues
Scoliosis
Osteoporosis (thinning of bones) due to lack of
estrogen
10. Obese weight (due to an underactive thyroid)
Drooping eyelids
Problems with breast development
Short fingers and toes
Extra skin on the neck (webbed neck)
Swelling of the hands and feet
Soft nails that turn upward at the ends
Irregular rotation of wrist and elbow joints
11. Loss of ovarian functions (infertility)
Heart defects
Kidney problems
Visual impairments
Ear infections and hearing loss
High blood pressure
Weak bones
12. Range of intellectual development usually normal
However, they seem to have difficulty with specific
skills
Learning disabilities
Especially in math
Behavioral problems
Problems with concentrating and remembering
13. Cytogenetics
60% - typical 45XO
40% are due to Structural or moasic
Usually caused by non-disjunction
Pair of sex chromosomes does not separate during
formation of either egg or sperm
When abnormal egg unites with normal sperm to form
embryo…
May end up missing that sex chromosome
Be X instead of XX
14. Investigations:
1. Barr Body
Examination
2. Dermatoglyphics
high total ridge count
Distal axial triradius
3. Karyotyping
15. Management
Counseling of parents and patient
Noramal or slightly less normal intelligance
Anabolic steroids at 10-12 yrs of age helps to gain
weight.
Oestrogen administration for secondary sexual
character.
16. Is Turner Syndrome “hereditary”?
Although it is a genetic
disorder, it is not
usually hereditary
There are no known
environmental causes
of the syndrome
Women with Turner
Syndrome are usually
infertile
17. Polysomy X
Polysomy X/ XXX syndrome/ Super female
affects females only, often asymptomatic
“XXX” instead of “XX”
Characteristics:
small head, tall stature
menstrual irregularities, delayed puberty, premature
menopause, infertility
19. Clinical features
Tall, thin, Eunuchoid.
Long legs
Poorly developed secondary sexual
characters
Testis are smaller
Scrotum & penis- Hypoplasia
Pubic, chin, chest & axillary hairs:
Absent / poorly developed
Normal intelligence, verbal IQ low
20. Gynaecomastia
Testicular biopsy: Hyalinization of seminiferous tubules
No spermatogenesis
Sterile
Chromatin positive cells
Low serum testosterone
High FSH & LH levels
21. Cytogenetics
Most cases- 47, XXY
15% cases: mosaic (46,XY / 47, XXY)
- Testicular development & mental status may be normal
60% cases: Maternal X
- Meiotic or postzygotic nondisjunction
- 47, XmXmY
40% cases: Paternal X
- Nondisjunction during first meiotic division of
spermatogenesis
- 47, XmXpY
24. Investigation
Cytogenetic studies:
Prenatally of fetus for screening
Postnatally: prompted by clinical signs:
Infants:- hypospadias, cryptorchidism, microphallus,
developmental delay
Kindergarten/elementary school - language delay,
learning disability/behavioral problems
Older boys/adolescent males- eunuchoid body habitus,
gynecomastia or small testes
Hormone testing
Age 12-14: plasma FSH, LH, estradiol and
testosterone, with minimal response to hcg stim
25. XYY syndrome
affects males only, 1:1000
Characteristics:
tall, about 3 inches taller than normal on average
severe acne
normal fertility, normal sexual drive
Increased aggressiveness
Associated with antisocial behaviour
26. Sex Developmental errors with
normal chromosomes
Ambiguous genitalia- difficult to assign sex.
Only testes, only ovaries, both tesis &Ovaries on
alternate side
Normal sex chromosomes: single gene defect
Karyotyping is imp. For Diagnosis & councelling.
27. Hermaphroditism
a hermaphrodite is an organism
that has reproductive organs normally
associated with both male and female
sexes.
Types
True Hermaphroditism
Pseuo Hermaphroditism
- Male Pseuo-hermaphroditism
- Female Pseuo-hermaphroditism Hermaphroditus, the son of
the Greek god Hermes and
the goddess Aphrodite,
origin of the word
"hermaphrodite".
28. True hermaphroditism
an intersex condition in which an individual is born
with ovarian and testicular tissue.
Ovary underneath each testicle on the other
Ovotestis
External genitalia are often ambiguous, the degree
depending mainly on the amount of testosterone produced
by the testicular tissue between 8 and 16 weeks of
gestation.
29. Causes
It can be caused by the division of one
ovum, followed by fertilization of each haploid
ovum and fusion of the two zygotes early in
development.
an ovum can be fertilized by two sperm followed
by trisomic rescue in one or more daughter cells.
Two ova fertilized by two sperm will occasionally
fuse to form a tetragametic chimera.
If one male zygote and one female zygote fuse, a
hermaphroditic individual may result.
It can be associated with mutation in the SRY
gene.
30. Pseudohermaphroditism
is the condition in which an organism is born with
secondary sex characteristics or a phenotype that is
different from what would be expected on the basis of
the gonadal tissue (ovary or testis).
if ovaries, then male external sexual anatomy
if testes, then female external sexual anatomy