Genetic Disease

Question 1

osteogenesis imperfecta

Answer 1

exhibit typical patterns of autosomal dominant or autosomal recessive inheritance and are, therefore, examples of so-called mendelian conditions

Question 2

nontraditional inheritance

Answer 2

fragile X–associated mental retardation syndrome

Question 3

genetic anticipation

Answer 3

where the severity of a Mendelian syndrome appears to progress with every generation of inheritance

Question 4

disorders that affect the mitochondrial genome

Answer 4

Leber hereditary optic neuropathy ( LHON ) and myoclonic epilepsy with ragged red fibers ( MERRF )

Question 5

Aneuploidy

Answer 5

any variation in chromosome number that involves individual chromosomes rather than entire sets of chromosomes. There may be fewer chromosomes or more chromosomes. the most common type of human genetic disease that does not affect DNA structure but instead alters the normal chromosome content per cell. Down syndrome

Question 6

Turner syndrome or Ullrich–Turner syndrome (also known as “Gonadal dysgenesis, 45, X

Answer 6

encompasses several conditions in human females, of which monosomy X (absence of an entire sex chromosome, the Barr body) is most common. It is a chromosomal abnormality in which all or part of one of the sex chromosomes is absent or has other abnormalities (unaffected humans have 46 chromosomes, of which two are sex chromosomes). In some cases, the chromosome is missing in some cells but not others, a condition referred to as mosaicism[2] or “Turner mosaicism”.

Question 7

The primary cause of any genetic disease

Answer 7

a change in the sequence or cellular content of DNA that ultimately deranges gene expression. Most genetic diseases are caused by an alteration in DNA sequence that alters the synthesis of a single gene product

Question 8

some genetic diseases are caused by

Answer 8

• structural rearrangements that result in deletion or duplication of a group of closely linked genes
• abnormalities during mitosis or meiosis that result in an abnormal number of chromosomes cell.

Question 9

gamete

Answer 9

one of two haploid reproductive cells, male (spermatozoon) and female (oocyte), whose union is necessary in sexual reproduction to initiate the development of a new individual.

Question 10

haploid

Answer 10

Denoting the number of chromosomes in sperm or ova, which is half the number in somatic (diploid) cells; the haploid number in normal human beings is 23

Question 11

mosaic

Answer 11

some mutations may arise during early embryogenesis, in which case tissues of the affected individual contain a mixtureof mutant and nonmutant cells.

Question 12

germline mosaicism

Answer 12

an individual may carry the mutation in some but not all of their germ cells

Question 13

somatic mosaicism

Answer 13

some but not all of their somatic cells

Question 14

gene

Answer 14

a short stretch of DNA, usually but not always

Question 15

DNA length

Answer 15

typically measured in base pairs, kilobase pairs (kb), or megabase pairs (Mb); chromosomes vary in length from about 46 Mb to 245 Mb.