Genetic Disorders – Chromosome Disorders

What are chromosome disorders? Chromsome – Large package of DNA which contains 1000’s of genes Chromsome Disorder– Extra or missing chromosome OR large piece is missing or extra

What types of chromosome disorders are there? Monosomy - Missing chromosome. Trisomy - Extra chromosome. Deletion – Piece of chromosome is missing. Addition – Piece of chromosome is extra.

How common are chromosome disorders? " Chromosomal abnormalities occur in about 1 of 200 live births” "Approximately 15 percent of all recognized pregnancies in human beings terminate in spontaneous abortion, and in about half of all spontaneous abortions, the fetus has a major chromosome abnormality."

How do chromosome disorders occur? 1. non-disjunction during meiosis 2. More likely to occur later in life

Autosomal Disorders Autosome – Any chromosome that isn’t X or Y DOWN SYNDROME Chromosome affected Trisomy 21

Autosomal Disorders Symptoms – - Learning disabilities - heart abnormalities - flatter head - larger tongue - broad hands and short fingers

Down Syndrome Age of onset - birth How is it diagnosed - Karyotype How common is it – 1 in every 800 births Life expectancy – In 1929, children with Down Syndrome lived 9 years. Today, people with Down Syndrome live to age 50 and beyond.

Down Syndrome Treatments/cures? – The life experience of people with Down's syndrome varies widely. Some children attend special schools, while others attend mainstream schools. Some adults live independently and find paid work. Others require support from family, and may attend day centers for people with learning difficulties. Video - What is it like to have it?

Sex Chromosome Disorders Sex Chromosome –X or Y Turners Syndrome Chromosome affected Monosomy of X or Y Only known human monosomy! Lost X is generally father’s.

Turner’s Syndrome Symptoms – - short - Webbing of neck - high, arched fingernails and toes - sterile - Heart problems

Turner’s Syndrome Age of onset - birth How is it diagnosed - Karyotype How common is it – 1 out of every 2500 female births Approximately 60,000 girls in U.S. 800 new cases each year Life expectancy – Normal.

Turner’s Syndrome Treatments/cures? – Growth hormone can be used to help with growth but the results of this are variable and depend on many factors such as the age at which the treatment was started. Estrogen therapy can be given to promote puberty. In adulthood, assisted conception may be available to overcome fertility problems.