Transcript Super Female

Chromosomal Aberrations
• Can be caused either by
– non-disjunction (failure of whole chromosomes to
separate during meiosis)
– translocation (bits of chromosomes that are reattached to other chromosomes).
• Individuals end up either with extra whole
or bits of chromosomes or with missing
whole or bits of chromosomes.
• These errors in meiosis increase in
frequency with increasing maternal age
(age 40 plus).
Super Female or Triple X Syndrome
•Genotype is XXX (47 chromosomes, extra X, trisomy)
•Females only (1 in a 1000)
•Often no distinguishing phenotype (physically or
mentally), especially in 1st year of life
•May have: slight neuro-motor developmental delay,
slight delay in speech and language, lack of coordination, immature or introverted behaviour,
•Height usually taller than average, head may be smaller
•Normal sexual development but increased chance of
infertility
•Academic performance varies from learning disabilities
to above average
Turner’s Syndrome
• Genotype is X (45 chromosomes, missing X,
monosomy)
• Females only (1 in 2500) - many die before birth
• Most have short stature & infertile - lack sexual
development (no ovarian development)
• May have a webbed neck, arms that turn out slightly at
the elbow, and a low hairline in the back of the head,
heart defects, kidney abnormalities
• May be prone to cardiovascular problems, kidney and
thyroid problems, skeletal disorders such as scoliosis
or dislocated hips, and hearing and ear disturbances.
• Kylie is 17 years old and
has Turner's syndrome.
She has competed in
gymnastics for several
international and national
games. She began taking
Hormone Replacement
Therapy at the age of 14
and she is now 5' 1 1/2".
Klinefelter’s Syndrome
• Genotype is XXY (47 chromosomes, extra X,
trisomy)
• Males only (1 in 700)
• Testes do not grow (stay small) – infertile
• Usually taller than average
• Sparse body hair and small muscle mass due
to low levels of testosterone
• May have delays in motor function, speech and
maturation and may have more feminine traits
• Intellect can be normal or slightly below normal
• Tony was diagnosed with
Klinefelter's syndrome
when he was 36. It was
discovered during
investigations into why he
was infertile. He is married
and works as a purchasing
manager for a health and
fitness company.
Super Male or XXY Syndrome
• Genotype is XYY (47 chromosomes, extra Y, trisomy)
• Males only (1 in a 1000)
• Usually tall (above 6 feet), slender and generally
appear and act normal.
• Produce high levels of testosterone. During
adolescence they usually have severe facial acne and
are poorly coordinated. They are usually fertile.
• May be: antisocial and/or aggressive and may have
below average intelligence/learning difficulties.
Down Syndrome
• Have 1 extra copy of chromosome 21 (47 chromosomes –
trisomy 21)
• Either gender equally affected (ranges from 1 in 1000 to 1 in 12
births as mother increases in age)
• Have extra copies of genes genes - leads to over-expression of
the involved genes, leading to an incorrect expression of the
traits
• Most have some mental retardation (degree varies widely)
• Physical features include low muscle tone, flat facial features,
with a small nose, upward slant to the eyes, small skin folds on
the inner corner of the eyes, small, abnormally shaped ears,
single deep crease across the center of the palm,
hyperflexibility, extra space between the big toe and the second
toe, enlarged tongue that tends to stick out.
• Have a higher risk of having heart defects, gastroesophageal
reflux disease, recurrent ear infections, obstructive sleep
apnea, epilepsy, hypothyroidism or celiac disease
We’ve highlighted just a few of the
more common Chromosomal
Disorders….but there are many more…
Note – in the following video, “p” and
“q” refer to the 2 arms of
chromosomes (chromatids)
• http://www.youtube.com/watch?v=ftEgxxd
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