amniotic band sequence
Monday 10 January 2005
Definition: Amniotic band sequence is a disruption sequence having a broad spectrum of clinical manifestations ranging from partial amputations to major craniofacial and limb-body wall defects.
Amniotic bands are the result of adhesions between the amnio and embryonic or fetal parts. Their frequency is comprised between 1/1200 to 1/15 000 births. Amniotic bands cause masive malformations with limb amputations, sever abdominal or cranial wall defects. Two different theories have been proposed: constrictive amniotic bands secondary to early amnion rupture, and vascular disruption events.
- limb anomalies
- intrauterine amputations
- limb constriction rings
- club feet
- abnormal dermatoglyphs
- craniofacial anomalies and cranial defects
- facial clefts (cleft lip, cleft palate)
- abnormal skull calicification
- abdominal wall anomalies
- abdominal constriction ring
constriction of the abdominal cord
The anomalies are characteristically asymmetrical.
Adams-Oliver syndrome (aplasia cutis-limb defects)
- scalp and/or skull defects at the vertex are associated with often asymmetric transverse limb defects.
- autosomal dominant disease is usually diagnosed after birth
other congenital transverse deficiencies not related with band constriction
amniotic placental-cerebral adhesion
Definition: Amniotic band sequence (OMIM #217100) comprises a broad clinical spectrum of defects that includes disruptions, deformations, and malformations.
Disruptions may be caused by adhesions or constrictions by amniotic bands of structures programmed to develop normally.(Amnion rupture sequence has been described clinically as rupture of the amnion followed by encircling of developing structures by strands of amnion. These may vary from constricting bands to limb reduction defects).
Deformations may result from distortion of embryologically normal structures (deformational defects such as scoliosis or talipes equinovarus may seen).
Amnion rupture may lead to oligohydramnios, which results in fetal constraint and tethering of fetal parts that may cause vascular engorgement, hemorrhage, edema, and tissue necrosis.
Malformations may result from the presence of amniotic bands in the early embryonic period that interfere with normal embryogenesis (Thoracoabdominoschisis, facial clefts, and encephaloceles also may be associated with amniotic adhesions, ruptured amnion, and amputation defects, and this has been referred to as the Limb Body Wall Complex (LBWC).
Amnion disruption sequence (ADS)
ADAM complex (amniotic deformities/adhesions/mutilations)
amniotic band disruption complex