Chromosomes 18, 19, and Y

By Daniel Borders

Chromosome Diagrams

Chromosome 18 Chromosome 19

Y Chromosome

Chromosome 18• Represents approximately 2.7% of total DNA in

cells• Believed that some genes on this chromosome

can disrupt the course of normal development• An extra 18th chromosome can lead to Edward’s

disease– Can lead to kidney malformations, heart defects, growth

development problems, etc.• Contains such genes as:

– ATPB1 – sends instructions for making proteins found throughout the body

– FECH – makes the certain enzyme that produces Heme (found in blood)

– LAMA3 – produces lamamins that help regulate cell growth

Chromosome 18 Cont’d

– LPINZ – sends information in processing fats

– SMAD4 – makes proteins involved in transmitting chemical signals

– TTR – makes transthyretin, which transports vitamin A and hormones

Chromosome 19

• Represents more than 2% of DNA in cells

• Associated with:– Breast Cancer– Alzheimer’s Disease

• Affects long-term memory, characterized by dementia (pre- , early, moderate, and advanced)

• Caused by the gene mutations of the genes APP, PSEN1, and PSEN2

• Genes in Chromosome 19– DMPK – not very well-understood,

apparently associated with normal function in heart, muscles, and brain cells

Chromosome 19 Cont’d

– MAN2B1 – creates enzymes that digest and recycle materials in cells

– HAMP – creates hepcidin, which helps maintain iron balance in the body

– PRX – creates periaxin, which promotes the efficient transmission of nerve impulses

– STK11 – creates an enzyme call serine, a tumor suppressor that keeps cells from growing and dividing too fast.

Y Chromosome

• One of two sex chromosomes in humans

• Found only in males• Genes in Y Chromosome

– SRY – triggers the development of testis– SHOX – makes a protein that helps to

regulate the performance of other genes– USPY9 – not well-understood, believed to

be associated with sperm development

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Y Chromosome Cont’d

• Defects associated with Y Chromosome– XX Chromosomes – occurs when the SRY

gene is translocated and misplaced onto the X chromosome, and another X chromosome is formed, while the life form is still a male

– XXYY Chromosomes – presence of an extra X and Y Chromosome, and prevents the testis from functioning normally, reducing the level of testosterone

– XYY Chromosomes – tends to result in tall stature and learning problems, but unclear why