1. Chromosomal abnormalities.
Valmiki Seecheran.
Year V | MBBS.

2. Introduction.
• A chromosome anomaly/ mutation is a
missing, extra or irregular portion of
chromosomal DNA.
• Error usually occurs in cell division following
meiosis/ mitosis.

3. Common types.
• Down’s syndrome.
• Turner’s syndrome.
• Patau’s syndrome.
• Edward’s syndrome.

4. Down’s syndrome – Trisomy 21.
• Mental abilities similar to a 8-9 year old.
– IQ (50-70).
• Poor immune function.
• Developmental delays.
• Increased risk of:
– CHD. – ASD & VSD (80%).
– Leukaemia. –Up to 15x more common. (ALL & AML).
– Thyroid disorders. – Hypothyroidism (50%)
– Mental illnesses.

5. Epidemiology.
• 1 per 1000 births.

6. Down’s syndrome – Trisomy 21.

7. Down’s syndrome – Trisomy 21.

8. Screening.
• All pregnant women should be screen
regardless of age.
• Can be used in combination to increase
detection rate.
• Amniocentesis/ chorionic villous sampling is
required to confirm diagnosis.
• Screening in 1st and 2nd trimester is better
than just screening in 1st trimester.

9. Screening.

10. Diagnosis.
• Based on physical appearance at birth.
• Chromosomal analysis to determine if
translocation is present and also help predict
the risk of the child’s parent with future
offspring.

11. Management
• Physicians & parents should be aware of the
range of psychomotor potential.
• Usual immunizations should be performed.
• Surgical management of associated conditions
should be provided.
• Regular screening is necessary to diagnose
epilepsy, hypothyroidism, auditory and visual
loss.

12. Turner’s syndrome.
• 45,X - absence of an entire sex chromosome,
Barr body.
• 1 in 2000, 1-500 phenotypic females.
• Short stature, low-set ears, webbed necks.
• Girls experience gonadal dysfunction –
amenorrhea & sterility.
• CHD, hypothyroidism, diabetes, auditory-
visual problems and auto-immune diseases.

13. Turner’s syndrome.

14. Kleinfelter vs. Turner’s syndrome.

15. Diagnosis.
• Postnatal.
– Diagnosed at birth due to heart problems, unusually
wide neck or swelling of hands and feets.
– Undeveloped puberty.
• Prenatal.
– Amniocentesis or chorionic villus sampling.
– Abnormal ultrasound findings – heart defect, kidney
abnormality, hygroma, ascites.
– Triple/quadruple maternal serum screen.

16. Treatment.
• Most people live long and healthy lives.
• Growth hormone/estrogen replacement
therapy are usually required.
• High risk of keloid formations – cosmetic
surgery.
• Multi-disciplinary team for screening –
cardiologist, endocrinologist, nephrologist,
psychologist.

17. Patau’s syndrome. (Trisomy 13)
• Some/ all of the cells contain extra genetic
material from chromosome 13.
• Nondisjunction of chromosomes during
meiosis.
• 1 in 10,000.

18. Patau’s syndrome. (Trisomy 13)

19. Patau’s syndrome. (Trisomy 13)
• Other.
– VSD/PDA.
– Dextrocardia
– Single umbilical artery.
• Urogenital.
– Abnormal genitalia.
– Kidney defects.
• MBJ.
– Polydactyly.
– Low set ears.
– Cyclopia.
– Cleft palate.
• CNS.
– Microcephaly.
– Meningomyelocele.
– MR/motor disorder.
– Holoprosencephaly (failure of the forebrain to divide)

20. Diagnosis.
• Based on clinical findings.
• Fetal chromosome testing will show trisomy
13.
• Quad screen does not provide reliable means
of screening.

21. Treatment & Prognosis.
• Case-by-case basis and depends on individual
circumstances.
• More than 80% of children die within first year
of life.
• Surgery may be necessary to repair heart
defects or cleft lip/palate.
• Physical/occupational and speech therapy will
help individuals maximise their potenial.

22. Edward’s syndrome. Trisomy 18.
• Presence of all or part of an extra 18th
chromosome in cells.
• Nondisjunction during meiosis.
• 1 in 6000 – most are females (80%).
• Low rate of survival – heart abnormalities,
kidney malformations.

23. Signs & Symptoms.
• VSD, ASD, PDA.
• Omphalocele – intenstines protruding outside
the body.
• Esophegeal atresia.
• MR – developmental delyas.
• Feeding difficulties.
• Arthrogryposis (multiple joint contractures at
birth).

24. Signs & Symptoms.
• Similar to Patau’s.
• Microcephahly
• Micrognathia (small jaw).
• Cleft lip/palate.
• Narrow eyelid folds – palpebral fissures.
• Ocular hypertelorism – wide space eyes.
• Undeveloped fingers/ nails.
• Clubfoot/ Rocker-bottom foot.
• Undescended testicles.
• Choroid plexus cysts – pockets of fluid on the brain.

25. Treatment.
• Supportive.
• Treat infections as appropriate. Sepsis is a
continuous concern.
• Nasogastric/gastrostomy supplmentation for
feeding problems.
• Multifaceted team – cardiologist, neonataologist,
ophthalmologist, orthopaedist, psychologist,
speech language pathologist,
• Genetic counselling.

26. Thank you.