BIO 151 Assignment Questions and Answers

DEPARTMENT: Medical Laboratory Science
COURSE CODE: BIO 151

Assignment Questions Write Short Note on:
Trisomy
Cri du chat syndrome
Wolf-hirshhorn syndrome
Velocandrofacial syndrome
Prader-will syndrome
Angelman syndrome
Sex chromosome aneuploidy

Assignment Answers

1. Trisomy

Trisomy is a genetic disorder where an individual has three copies of a chromosome instead of the usual two. It results from nondisjunction during cell division. Common types include Trisomy 21 (Down syndrome), Trisomy 18 (Edwards syndrome), and Trisomy 13 (Patau syndrome). Trisomy often leads to developmental delays, intellectual disabilities, and physical abnormalities.

2. Cri du Chat Syndrome

Cri du Chat Syndrome (French for “Cry of the Cat” is a rare genetic disorder caused by a deletion on the short arm of chromosome 5 (5p deletion). Affected babies have a high-pitched cry resembling a cat’s meow, along with intellectual disability, microcephaly, low birth weight, and distinctive facial features like widely spaced eyes and a small jaw.

3. Wolf-Hirschhorn Syndrome

This is a genetic condition caused by a deletion on the short arm of chromosome 4 (4p deletion). It is characterized by severe developmental delay, intellectual disability, seizures, and distinctive facial features, including a “Greek warrior helmet appearance” with a broad flat nasal bridge and high forehead.

4. Velocardiofacial Syndrome (VCFS)

Also known as 22q11.2 deletion syndrome, VCFS affects multiple body systems due to a deletion on chromosome 22. Symptoms include congenital heart defects, cleft palate, learning disabilities, immune system problems, and distinctive facial features. It is one of the most common genetic syndromes after Down syndrome.

5. Prader-Willi Syndrome (PWS)

PWS is a genetic disorder caused by the absence of paternal gene expression on chromosome 15 (15q11-q13). It is characterized by poor muscle tone, feeding difficulties in infancy, later excessive appetite leading to obesity, intellectual disability, and behavioral issues.

6. Angelman Syndrome

This is caused by the loss of maternal gene expression on chromosome 15 (15q11-q13), the opposite of Prader-Willi Syndrome. It leads to severe developmental delays, speech impairment, frequent laughter, hyperactivity, and ataxic movement (jerky walking). People with Angelman syndrome often have a happy demeanor.

7. Sex Chromosome Aneuploidy

This refers to conditions where individuals have an abnormal number of sex chromosomes (X or Y). Examples include:

• Klinefelter Syndrome (XXY): Affects males, causing infertility, tall stature, and reduced testosterone.

• Turner Syndrome (XO): Affects females, leading to short stature, infertility, and heart defects.

• Triple X Syndrome (XXX): Usually mild, can cause taller height and learning difficulties in females.

• XYY Syndrome: Affects males, often resulting in taller stature and sometimes mild developmental delays.