Chromosomal Disorder

Question 1

XYY syndrome (sometimes referred to as ‘super-males’) is a condition where males possess an extra Y chromosome, producing the 47, XYY karyotype.

It is usually asymptomatic. Affected individuals tend to be taller than average. Testosterone levels are normal and fertility and sexual development are usually unaffected.

There is an increased risk of learning difficulties. Aggression is not seen in higher levels than the normal population.

Answer 1

XYY syndrome (sometimes referred to as ‘super-males’) is a condition where males possess an extra Y chromosome, producing the 47, XYY karyotype.

It is usually asymptomatic. Affected individuals tend to be taller than average. Testosterone levels are normal and fertility and sexual development are usually unaffected.

There is an increased risk of learning difficulties. Aggression is not seen in higher levels than the normal population.

Question 2

Klinefelters syndrome

Answer 2

Klinefelters syndrome is caused by the presence of one or more extra copies of the X chromosome in a male’s cells. Extra genetic material from the X chromosome interferes with male sexual development, preventing the testes from functioning normally and reducing the levels of testosterone. A shortage of testosterone can lead to delayed or incomplete puberty, genital abnormalities, gynecomastia, reduced facial and body hair, and infertility. Affected individuals may also have learning disabilities, delayed speech and language development, and a shy and unassuming personality.

Typically, people with Klinefelters syndrome have one extra copy of the X chromosome in each cell, (a total of two X chromosomes and one Y chromosome referred to as 47,XXY). Less commonly, affected individuals may have two or three extra X chromosomes (48,XXXY or 49,XXXXY). As the number of extra sex chromosomes increases, so does the risk of learning problems, intellectual disability, birth defects, and other issues.

Some people with features of Klinefelters syndrome have the extra X chromosome in only some of their cells (mosaic). Individuals with mosaic Klinefelters syndrome may have milder signs and symptoms, depending on how many cells have an additional X chromosome.

Question 3

Di George syndrome

Answer 3

Almost all cases of Di George syndrome result from a deletion on chromosome 22. The signs and symptoms are varied and the following mnemonic is used to summarise some of these as well as to help you recall the chromosome involved: Cardiac abnormalities (tetralogy of Fallot)
Abnormal facies (almond-shaped eyes, low-set ears)
Thymic aplasia (hence recurrent infections)
Cleft palate
Hypocalcemia/Hypoparathyroidism (causing short stature and seizures)
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A degree of learning disability is also usually present. Other psychiatric conditions such as depression, ADHD and schizophrenia are also overrepresented in this group.
Next question

Question 4

Angleman syndrome or Fragile X

Answer 4

Flapping hand movements

Question 5

Prader willi

Answer 5

Hyperphagia

Question 6

Patau syndrome

Answer 6

Overlapping of fingers over thumb

Question 7

Lesch-Nyhan syndrome or Smith Magenis syndrome

Answer 7

Pronounced self injurious behaviour