Test 1: Genetics

Question 1

Anomaly

Answer 1

a structural feature that departs from normal; used interchangeably with
‘dysmorphic’

Question 2

Carrier

Answer 2

a clinically unaffected individual who may have clinically affected offspring

Question 3

Congenital

Answer 3

present at birth; usually refers to defect that may or may not be genetic in origin

Question 4

Dominant mutations

Answer 4

mutations that produce an abnormal clinical phenotype (disorder or trait)
when present in the heterozygous state (a singe dose of the mutant gene)

Question 5

Dysmorphic

Answer 5

describes a body part that has not followed the normal pattern of growth or
formation; used interchangeably with ‘anomaly’

Question 6

Familial

Answer 6

implies that a trait aggregates in families; may be due to genetic factors or non-
genetic factors, i.e. diet

Question 7

Fragile site

Answer 7

gap or defect in the continuity of a chromosome when strained, i.e. fragile X site;
many are apparent only when cells are cultured under special conditions

Question 8

Human Genome Initiative (Project)

Answer 8

collective name for several projects designed to map and
eventually sequence the human genome

Question 9

Minor anomalies

Answer 9

unusual clinical features that occur relatively commonly in the normal population; they have no medical or cosmetic consequences; alone they are of little significance, but they often occur together with major developmental defects and their
presence helps to make diagnosis of syndromes;

ex: unusual creases in the hand, and unusual shape of the ears

Question 10

Multifactorial

Answer 10

implies that multiple factors, genetic and non-genetic, are involved in causing a
trait or disorder

Question 11

Mutation

Answer 11

a permanent and inheritable change in genetic material; types of mutations include
point mutations, deletions, insertions, and changes in number and structure of chromosomes

Question 12

Penetrance

Answer 12

refers to the clinical expression of a gene or mutations of a gene; if a mutation
produces a recognizable phenotype in a patient, the mutation is said to be penetrant; reduced
penetrance means that individuals who harbor a mutation do not always manifest the mutant
phenotype clinically

Question 13

Phenotype

Answer 13

the appearance (physical, biochemical, and physiological) of an individual which
results from the interaction of environment and genotype

Question 14

Recessive mutations

Answer 14

mutations that produce an abnormal clinical phenotype when present in
the homozygous state (double dose of the mutation)

Question 15

Malformation

Answer 15

A structural defect of an organ or body part due to an intrinsically abnormal developmental process,

i.e. cleft lip/palate; polydactyly

Question 16

Major malformations

Answer 16

those that have medical, surgical, or cosmetic significance; these occur in 2-3%
of liveborn infants.

Question 17

Minor malformations

Answer 17

Common (5-40%)

are those that are insignificant except that they are important clues to diagnosis; if
there are 3 or more minor malformations, you should suspect a genetic condition/major malformation
is present

Question 18

Disruption

Answer 18

Ex. Amniotic banding

an abnormal breakdown of tissue in the normal fetus resulting in a defect of an organ or body part

Question 19

Deformation

Answer 19

Ex. Plagiocephaly

An alteration in form, shape, or position of an organ or body part by mechanical forces

Question 20

Dysplasia

Answer 20

Ex. Skeletal dysplasia, renal dysplasia, singular palmer crease in individuals with Down Syndrome

an abnormal organization of cells in tissues that has structural consequences

Question 21

Syndrome

Answer 21

A recognizable pattern of anomalies which have a common cause, either genetic or environmental.

Question 22

Sequence

Answer 22

Ex. Spina bifida-the neural tube fails to close, resulting in interrupted spinal cord/paralysis, then hydrocephalus, neurogenic bladder, and
club feet.

A pattern of anomalies that are the secondary effects of an initial defect.

Question 23

Association

Answer 23

A non-random occurrence of multiple anomalies.

Question 24

Chromosomal syndrome

Answer 24

Occur when there is an addition or deletion of a whole or part of a chromosome.

◦ Trisomy 21 (Down Syndrome); 1/600 births (incidence varies with maternal age)
◦ Monosomy X (Turner Syndrome)
◦ Klinefelter Syndrome

Question 25

Trisomy 21 (Down Syndrome)

Answer 25

Chromosomal syndrome

Accounts for 20% of all people with intellectual disability (ID)

Traits
◦ Short stature as a child, often grow slowly, and as an adult shorter than average
◦ low muscle tone throughout the body, greater at the proximal body (core) vs limbs
◦ A short, wide neck with excess fat and skin, less obvious as the child gets older
◦ Short, stocky arms and legs, may also have a wider than normal space between the big toe and
second toe
◦ A single crease across the center of the palms of the hands, called a transverse palmar crease
◦ Small, low-set ears
◦ Flat nasal bridge
◦ Larger than average tongue

Question 26

Monosomy X (Turner Syndrome)

Answer 26

Chromosomal syndrome

Sex chromosomal abnormality in females (One X)

Symptoms include short stature, low-set ears, a wide or web-like neck, a narrow roof of the mouth, and drooping eyelids

Question 27

Klinefelter Syndrome

Answer 27

Chromosomal syndrome

Extra X chromosome in males

long limbs, slim stature, possible behavioral problems

poor motor function but can walk

Question 28

Contiguous Gene Deletion Syndrome

Answer 28

Occur when there is a deletion of a set of genes that are close together on one chromosome.

◦ Prader-Willi Syndrome–deletion of paternal 15q
◦ Angelman Syndrome–deletion of maternal 15q
◦ Williams Syndrome– deletion of 7q

Question 29

Prader-Willi Syndrome

Answer 29

Contiguous Gene Deletion Syndrome

Partial deletion of chromosome 15, paternal source

mild intellectual impairment, short, and obese

Question 30

Angelman Syndrome

Answer 30

Contiguous Gene Deletion Syndrome

Partial deletion of chromosome 15, maternal source

a rare genetic disorder that affects the nervous system and causes severe developmental delay, intellectual disability, and speech impairment

severe cognitive impairment, arms held with flexed wrists and elbows, frequent laughter, autism

Physical features: Small head, wide mouth, prominent chin, deep-set eyes, and distinctive facial appearance

Question 31

Williams Syndrome

Answer 31

Contiguous Gene Deletion Syndrome

Autosomal dominant

deletion from chromosome 7

a multisystem disorder characterized by cardiovascular disease (elastin arteriopathy, most often manifesting as supravalvar aortic stenosis), developmental delay, usually mild intellectual disability, a specific cognitive profile, unique personality characteristics,

Question 32

Single Gene Syndromes

Answer 32

Occur when there is an abnormality of one gene; there are more than 5,000 of these syndromes currently known.

◦ Sickle cell anemia (recessive)
◦ Marfan syndrome
◦ Duchenne muscular dystrophy
◦ Cystic fibrosis

Question 33

Cystic fibrosis

Answer 33

Single Gene Syndromes

Autosomal recessive

a genetic disorder that causes the body to produce thick, sticky mucus that can block airways and damage organs

endurance limited due to pulmonary involvement, may participate in some sports

Cause: A faulty protein in the body that affects the production of mucus and sweat

Question 33

Duchenne muscular dystrophy

Answer 33

Single Gene Syndromes

X linked deletion

delay of early milestones
loss of motor abilities through childhood leading to wheelchair use

DMD is caused by a mutation in the gene for dystrophin, a protein that helps support muscle cells. This mutation leads to a lack of dystrophin, which causes the muscle cell membrane to become permeable and eventually die.

Question 34

Marfan Syndrome

Answer 34

Single Gene Syndromes

Autosomal dominant

affects bodies connective tissues, which support bones, muscles, organs, and skin

tall, thin, long limbs

Question 35

VACTERL

Answer 35

Association acronyms

Vertebral anomalies

Anal atresia

Cardiac defects

Tracheo-

Esophageal fistula

Renal defects

Limb defects

Question 36

CHARGE

Answer 36

Coloboma of eye

Heart defect

Atresia choanae

Retarded growth/development

Genital hypoplasia

Ear anomalies