This document discusses various congenital limb defects including: - Meromelia which is the partial absence of a limb - Amelia which is the complete absence of a limb - Phocomelia where the long bones are absent and the hands/feet are attached to the trunk - Micomelia where all limbs are present but abnormally short The causes of many limb defects are genetic mutations affecting genes like HOXD13, TBX5, COL1A1, COL1A2, and fibrillin. Environmental factors like vascular problems in utero can also lead to transverse limb deficiencies.

1. EMBRYOLOGY
TOPIC:
LIMB DEFECTS

2. 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

3. MEROMELIA :
Partial absent on limb
AMELIA:
Complete absence of a limb

4. PHOCOMELIA:
Long bones are absent
Hand or feet attached to trunk
MICROMElIA:
all limbs are present but abnormally short

5. BRACHYDACTYLY:
Short digits of hand and foot
SYNDACTYLY
Fused fingers and toes

6. POLYDACTYLY:
The presence of extra finger or toe
ECTRODACTYLY:
Absence of digits

7. 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

8. HOLT –ORAM SYNDROME:
 Upper limb abnormalities
 heart defects
 Absent digits
 Absent radius
 Hypoplasia
 Polydactyly
 Syndactyly
CAUSES:
mutation in TBX5 gene

9. 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

10. 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

11. 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

12. 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