EMBRYOLOGY

TOPIC:

LIMB DEFECTS

Congenital Limb Deformities:

Congenital limb deformities are birth defects in which a

fetus’s limbs do not form properly while in uterus

Following are the possibilities

• A baby may be have missing limbs

• A baby may be have extra limb

• Over growth of limb

• Under growth of limb

• fingers or toes may fail to separate

MEROMELIA :

Partial absent on limb

AMELIA:

Complete absence of a limb

PHOCOMELIA:

Long bones are absent

Hand or feet attached to trunk

MICROMElIA:

all limbs are present but abnormally short

BRACHYDACTYLY:

Short digits of hand and foot

SYNDACTYLY

Fused fingers and toes

POLYDACTYLY:

The presence of extra finger or toe

ECTRODACTYLY:

Absence of digits

CLEFT HAND AND FOOT

Consist of a cleft between 2nd

and 4th Metacarpal bone

3rd metacarpal is absent

Thumb, index finger ,4th and 5th finger is fused

CAUSES :

Mutation in the HOXD13 gene results in hand – foot –genital syndrome

HOLT –ORAM SYNDROME:

Upper limb abnormalities

heart defects

Absent digits

Absent radius

Hypoplasia

Polydactyly

Syndactyly

CAUSES:

mutation in TBX5 gene

OSTEOGENESIS IMPERFECTA:

Shortening ,bowing and hypomineralization

Of long bones

It can cause fractures

Causes:

Mutation in COL1A1 OR COL1A2 gene

that form type 1 collagen

MARFAN SYNDROME :

Individuals are long slender

Long thin limbs

Long thin face

CAUSES:

Mutation in fibrillin

CLUB FOOT :

Foot pointed downward

Foot is rotated toward the other foot

Cause : mutation of PITX1 gene

CONGENITAL ABSENCE OF RADIUS :

Radius is absent

CRANIOSYNOSTOSIS RADIAL APLASIA SYNDROME :

(Beller Gerold syndrome)

They have stenosis of one or more

Cranial sutures

Absence of radius

TRANSVERSE LIMB DEFICIENCIES :

Proximal structures are intact

Structures distal to transverse plane are

Partially or completely absent

CAUSES :

Vascular thrombosis

Vasoconstriction

CONGENITAL HIP DISLOCATION :

Under development of acetabulum

And head of femur

Common in female newborns

Occur after birth