GENETIC DISORDERS IN GENETIC DISORDERS IN HUMAN REPRODUCTIONHUMAN REPRODUCTIONTurner SyndromeTurner Syndrome

Khalid EsmailKhalid EsmailLeslie NewcombeLeslie Newcombe

Nicola YangNicola Yang

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Introduction

Also: Gonadal DysgenesisMost common sex chromosome abnormality in females– Occurs in 1 per 2,500 girls– Described by Dr. Henry Turner in

1938; chromosomal abnormality discovered in 1960

Normal: has two X chromosomes; 46 in allTurner syndrome: has a missing or damaged X chromosome in some/all cells; only 45 in all

Normal female karyotype

Karyotype with Turner SyndromeImages courtesy of North Central Regional Technology in Education Consortium

(http://www.ncrtec.org/tl/camp/gene/female.gif)

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CausesX-Chromosome Monosomy– Male gamete 22 autosomes (“regular” chromosomes) and one

sex chromosome.

(Monosomy: X-chromosome lost during meiosis of sperm)Normal cell division during meiosis

Monosomy: sex chromosome lost during sperm meiosis

All images courtesy of National Institute of Child Health and Human Development All images courtesy of National Institute of Child Health and Human Development Source: http://turners.nichd.nih.gov/ClinFrIntro.htmlSource: http://turners.nichd.nih.gov/ClinFrIntro.html

X-Chromosome Defects- Missing / damaged portion of X-chromosome-Results in small, large or no effects

- Some genes absent- Activate usually silent genes

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X-Chromosome MosaicismLost during the early stages of embryonic development– Some cells still have two, some only one – Effects not as evident

X-chromosome lost during embryonic

development

All images courtesy of National Institute of Child Health and Human All images courtesy of National Institute of Child Health and Human Development Development Source: Source: http://turners.nichd.nih.gov/ClinFrIntro.htmlhttp://turners.nichd.nih.gov/ClinFrIntro.html

Causes

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Diagnosis

Karyotyping– Chromosomal pattern– Only way to confirm

diagnosis

It is done…– Before birth:

amniocentesis or chorionic villous sampling

– After birth: blood test

Chorionic villous sampling: sample of placental tissue.

Image courtesy of http://www.nlm.nih.gov/medlineplus/ency/imagepages/9181.htm

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Identifying features & Symptoms

Problems with body development and body systems

Primary Features

- Ovarian Failure- Medical Problems- Short Stature

Growth curve comparing the average heights of girls without

TS, the average heights of girls with TS

and the average heights of girls with TS

that are not treated

Growth chart for children with Turner syndrome. Source: Rieser P, Davenport M. Turner Syndrome: A Guide for Families. Houston, TX: Turner Syndrome Society of the United States; 2002. Data derived from Lyon et al.

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Identifying Features:Secondary Features

Puffy hands and feet at birth

Webbed neck Prominent

Rotated Ears

Ptosis: drooping eyelids

Images courtesy of www.medscape.com/ viewarticle/445555_1, http://health.families.com/turner-syndrome-3417-3419-gem and http://www.nlm.nih.gov/medlineplus/ency/imagepages/1111.htm

Shield Chest

Nail dysplasia

Cubitus Valgus

Low posterior hairline

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Treatment

No known cure for chromosome abnormality

However,Injections of human growth hormones (HGH), estrogen, and progesterone – Trigger further

developmentHGH injection

Image courtesy of Image courtesy of http://www.hghforheight.com/injection.gifhttp://www.hghforheight.com/injection.gif

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Summary --- Conclusion • TS: Having damaged or missing portion of X- chromosome

• Three causes

• X- Chromosome Defects

•X- Chromosome Monosomy

•X- Chromosome Mosaicism

• Diagnosed with Karyotyping

• Many features/symptoms: ovarian failure, short stature etc.

• Not prone to mental retardation

• No cure for TS

• Injections of hormones may stimulate development

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Works Cited

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