Chapter 12

Question 1

Radiologists use the appearance of various ossification centers to determine whether a child has reached his or her proper maturation age

Answer 1

Bone age

Question 2

obtained from ossification studies in the hands and wrists of children

Answer 2

Bone age

Question 3

Abnormalities of the limbs vary greatly, and they may be represented by partial [___] or complete absence [___] of one or more of the extremities

Answer 3

meromelia - Amelia

Question 4

Sometimes, the long bones are absent, and rudimentary hands and feet are attached to the trunk by small, irregularly shaped bones [____, a form of meromelia]

Answer 4

phocomelia

Question 5

Sometimes, all segments of the extremities are present but abnormally short [____]

Answer 5

micromelia

Question 6

Many mothers of these infants had taken ___, a drug widely used as a sleeping pill and antinauseant.

Answer 6

thalidomide

Question 7

Sometimes, the digits are shortened [___]

Answer 7

brachydactyly

Question 8

If two or more fingers or toes are fused, it is called ___

Answer 8

syndactyly

Question 9

The presence of extra fingers or toes is called ___. The extra digits frequently lack proper muscle connections

Answer 9

polydactyly

Question 10

Abnormalities involving polydactyly are usually bilateral, whereas absence of a digit [___], such as a thumb, usually occurs unilaterally

Answer 10

ectrodactyly

Question 11

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

Answer 11

Cleft hand and foot

Question 12

The role of the HOX genes in limb development is illustrated by two abnormal phenotypes produced by mutations in this family of genes: Mutations in ___ result in hand-foot genital syndrome, characterized by fusion of the carpal bones and small short digits

Answer 12

HOXA13

Question 12

The role of the HOX genes in limb development is illustrated by two abnormal phenotypes produced by mutations in this family of genes: Mutations in HOXA13 result in____, characterized by fusion of the carpal bones and small short digits

Answer 12

hand-foot genital syndrome

Question 13

Mutations in ___ result in a combination of syndactyly and polydactyly [synpolydactyly]

Answer 13

HOXD13

Question 14

Mutations in HOXD13 result in a combination of syndactyly and polydactyly [___]

Answer 14

synpolydactyly

Question 15

__ mutations [chromosome 12q24.1] result in Holt-Dram syndrome, characterized by upper limb abnormalities and heart defects consistent with a role for this gene in upper limb and heart development

Answer 15

TBX5

Question 16

TBX5 mutations [chromosome 12q24.1] result in ___, characterized by upper limb abnormalities and heart defects consistent with a role for this gene in upper limb and heart development

Answer 16

Holt-Dram syndrome

Question 17

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

Answer 17

Osteogenesis imperfecta

Question 18

In most cases, dominant mutations in the __ or __ genes involved in production of type I collagen cause the abnormalities

Answer 18

COL1A1 or COL1A2

Question 19

In most cases, dominant mutations in the COL1A1 or COL1A2 genes that are involved in production of ___ cause the abnormalities

Answer 19

type I collagen

Question 20

___ is caused by mutations in the FIBRILLIN [FBN1] gene located on chromosome 15q21.1

Answer 20

Marfan syndrome

Question 21

Marfan syndrome is caused by mutations in the ___ gene located on chromosome 15q21.1

Answer 21

FIBRILLIN [FBN1]

Question 22

___ may be caused by arthrogryposis but is more commonly considered to be idiopathic in origin

Answer 22

Clubfoot

Question 23

___ usually involves more than one joint and may be caused by neurological defects [motor horn cell deficiency, meningomyelocele], muscular abnormalities [myopathies, muscle agenesis], and joint and contiguous tissue problems [synostosis, abnormal development]

Answer 23

Arthrogryposis [congenital joint contractures]

Question 24

___ is usually a genetic abnormality observed with malformations in other structures, such as craniosynostosis-radial aplasia syndrome [Baller—Gerold syndrome]

Answer 24

Congenital absence or deficiency of the radius

Question 25

Congenital absence or deficiency of the radius is usually a genetic abnormality observed with malformations in other structures, such as ___ [Baller—Gerold syndrome]

Answer 25

craniosynostosis-radial aplasia syndrome

Question 26

___ may cause ring constrictions and amputations of the limbs or digits

Answer 26

Amniotic bands

Question 27

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

Answer 27

Transverse limb deficiencies

Question 28

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

Answer 28

Congenital hip dislocation