Chapter 12

Question 1

This is obtained from ossification studies in the hands and wrists of children to determine if they have reached their proper maturation age

Answer 1

Bone age

Question 2

meromelia means

Answer 2

partial absence

Question 3

amelia means

Answer 3

complete absence

Question 4

A type of meromelia where the long bones are absent, and rudimentary hands and feet are attached to the trunk by small, irregularly shaped bones

Answer 4

Phocomelia

Question 5

All segments of the extremeties are present but abnormally short

Answer 5

Micromelia

Question 6

a drug widely used as a sleeping pill and anti-nauseant that caused a characteristic syndrome of malformations consisting of absence or gross deformities of the long bones, intestinal atresia, and cardiac anomalies.

Answer 6

Thalidomide

Question 7

what weeks of gestation are the most sensitive period for induction of the limb defects

Answer 7

4th and 5th weeks

Question 8

Shortened digits are termed

Answer 8

Brachydactyly

Question 9

If two or more fingers or toes are fuse, it is called

Answer 9

syndactyly

Question 10

mesenchyme between prospective digits in hand and footplates is removed by

a. degradation
b. excretion
c. apoptosis

Answer 10

C

Question 11

Presence of extra fingers or toes

Answer 11

Polydactyly (usually bilateral)

Question 12

Absence of a digit

Answer 12

ectrodactyly (usually occurs unilaterally)

Question 13

consists of an abnormal cleft between the second and fourth metacarpal bones and soft tissues.

Answer 13

Cleft hand and foot

Question 14

True or False

In the cleft hand and foot, the third metacarpal and phalangeal bones are almost always absent

Answer 14

True

Question 15

In the cleft hand and foot, index finger
and the fourth and fifth fingers may be fused

Answer 15

True

Question 16

Mutations in HOXA13 result in

Answer 16

hand-foot-genital syndrome

Question 17

This syndrome is characterized by fusion of the carpal bones and small short digits.

Affected females often have a partially [bicornuate] or a completely [didelphic] divided uterus and abnormal positioning of the urethral orifice

Answer 17

hand-foot-genital syndrome

Question 18

What gene is mutated that results in a combination of syndactyly and polydactyly (synpolydactyly)

Answer 18

HOXD13

Question 19

Holt-Oram Syndrome results due to the mutation of what gene

Answer 19

TBX5 (chromosome 12q24.1)

Question 20

This syndrome is characterized by upper limb abnormalities and heart defects
consistent with the role of the TBX5 gene in the upper limb and heart development.

Answer 20

Holt-Oram Syndrome

Virtually all types of limb defects affecting the upper limb have been observed, including absent digits, polydactyly, syndactyly, absent radius, and hypoplasia of any of the limb bones. Heart defects include atrial and ventricular septal defects and conduction abnormalities.

Question 21

characterized by shortening, bowing, and hypomineralization of the long bones of the limbs that can result in fractures and blue sclera

Answer 21

Osteogenesis imperfecta

Question 22

production of which type of collagen cause osteogenesis imperfecta

a. Type I
b. Type II
c. Type III
d. Type IV

Answer 22

Type I.

genes involved in the production of this collagen are COL1A1 and COL1A2

Question 23

caused by mutations in the FIBRILLIN [FBN1] gene located on chromosome 15q21.1. Affected individuals are usually tall and slender with long thin limbs
and a long thin face

Answer 23

Marfan Syndrome

Other characteristics include sternal defects [pectus excavatum or ca- rinatum], joint hyperflexibility, dilatation and/or dissection of the ascending aorta, and dislocation of the lens of the eye.

Question 24

It usually involves more than one joint and may be caused by neurological defects
[motor horn cell deficiency, meningomyelocele], in origin

Answer 24

Arthrogryposis
[congenital joint contractures]

Question 25

recent studies have linked clubfoot with mutations and microdeletions involving which transcription factor

Answer 25

PITX1

Question 26

Congenital absence or deficiency of the radius is usually a genetic abnormality observed with malformations in other structures, such as _________.

Answer 26

craniosynostosis-radial aplasia syndrome
[Baller-Gerold syndrome].

These individuals have synostosis in one or more cranial sutures, absence of the radius, and other defects.

Question 27

may cause ring constrictions and amputations of the limbs or digits

Answer 27

Amniotic bands

Question 28

are limb defects in which proximal structures are intact, but structures distal to a transverse plane are partially or completely absent

Answer 28

Transverse limb deficiencies.

The defects may be due to disruption of the
AER or its signaling or to vascular abnormalities such as thromboses or vasoconstriction.

Question 29

consists of underdevelopment of the acetabulum and head of the femur.

Answer 29

Congenital hip dislocation.
It is common mostly in female newborns