GENETIC DISORDERS IN HUMAN REPRODUCTION Turner Syndrome Khalid Esmail Leslie Newcombe Nicola Yang

Introduction Also: Gonadal Dysgenesis Most 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 all Turner syndrome: has a missing or damaged X chromosome in some/all cells; only 45 in all Normal female karyotype Karyotype with Turner Syndrome Images courtesy of North Central Regional Technology in Education Consortium (

Causes X-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 Source: X-Chromosome Defects - Missing / damaged portion of X-chromosome -Results in small, large or no effects - Some genes  absent - Activate usually silent genes

X-Chromosome Mosaicism Lost 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 Development Source: Causes

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

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; Data derived from Lyon et al.

Identifying Features: Secondary Features Puffy hands and feet at birth Webbed neck Prominent Rotated Ears Ptosis: drooping eyelids Images courtesy of viewarticle/445555_1, gem and viewarticle/445555_1 Shield Chest Nail dysplasia Cubitus Valgus Low posterior hairline

Treatment No known cure for chromosome abnormality However, Injections of human growth hormones (HGH), estrogen, and progesterone –Trigger further development HGH injection Image courtesy of

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

Works Cited PLEASE VISIT OUR SITE: for further information and additional links