ANTIPHOSPHOLIPID ANTIBODY SYNDROME (APLAS)

APLAS is characterized by the production of auto-antibodies against protein epitopes which form complexes with negatively charged phospholipids in cell membranes (1). They are found in patients with systemic lupus erythematosis (SLE), which is a chronic autoimmune disease that typically presents in women during their childbearing years. The primary association with SLE is the universal presence of maternal IgG autoantibodies to Ro/SSA and La/SSB in neonatal lupus syndrome.

Clinical Features (2)	Laboratory Features
1. Recurrent venous or arterial thrombosis. 2. Recurrent fetal loss. 3. Thrombocytopenia	Antiphospholipid antibodies: 1. Lupus anticoagulant or 2. Anticardiolipin antibodies

ULTRASOUND

Antiphospholipid antibodies are associated with an increase in arterial and venous thrombosis despite the prolongation of the activated partial thromboplastin time (1,3). Transplacental passage of maternal immunoglobulins is maximal at 16-17 weeks of gestation and approximates the time that the fetal cardiac conduction reaches full maturity (4). Histological studies have revealed the deposition of Ro/SSA and La/SSB antigens, and specific antibody in the cardiac tissue of fetuses with congenital heart block. The risk of an antibody-positive women having a child with congenital heart block (CHB) is estimated at 0.5-2%, whereas the risk of a second affexted child rises to 10-20% (5). Mothers of affected infants do not suffer conduction abnormalities, supporting the idea that a unique fetal environment determines disease expression.

• Recurrent first trimester miscarriage (pregnancy loss rate = 80-90 % with the majority occurring in the first trimester) (6,7).
• Second or third trimester pregnancy loss (often unexplained).
• Early severe eclampsia.
• Congenital heart block – most occur between 16 and 30 weeks of gestation (8). It is characterized by persistent fetal bradycardia leading to congestive heart failure or hydrops (9). The mortality rate of antibody-related congenital heart block is at least 20%, and most neonates require a permanent pacemaker within the first year of life (8).
• Early onset IUGR.
• Abruptio placenta.
• Thrombosis of placental vessels resulting in ischemia and infarction.
• Direct damage to the trophoblastic tissue.
• Abnormal flow velocity waveforms in the umbilical artery.

REFERENCES

1. Sait KH, Van den Hof MC, Robinson KS. Antiphospholipid antibody syndrome in pregnancy. J Soc Ob Gyn Can 1997; :1083-1092.
2. Harris EN. The second international anto-cardiolipin standardization workshop / The Kingston Anti-Phospholipid Antibody Study (KAPS) Group. Am J Clin Path 1990;94:476-484.
3. Rote NS, Walter A, Lyden TW. Antiphospholipid antibodies - Lobsters or Red Herrings ? Am J Reprod Immunol 1992;28:31-37.
4. Brustein D, Rodriguez JM, Minkin W et.al. Familial lupus erythematosus.1977;238:2294.
5. McCune AB, Weston WI, Lee LA. Maternal and fetal outcome in neonatal lupus erythematosus. Arthritis Rheum 1986;29:1269.
6. Harris EN, Spinnato JA. Should anticardiolipin tests be performed on otherwise healthy pregnant women ? Am J Obstet Gynecol 1991;165:1272-1277.
7. Pattison NS, Chamley LW, McKay EJ et.al. Antiphospholipid antibodies in pregnancy: prevalence and clinical associations. Br J Obstet Gynaecol 1993;100:909-913.
8. Buyon JP, Waltuck J, Klein C et.al. In utero identification and therapy of CHB. Lupus 1995;4:116.
9. Buyon JP, Hiebert R, Copel J et.al. Autoimmune-associated congenital heart block: demographics, mortality, morbidity, and recurrence rates obtained from a national lupus registry. J Am Coll Cardiol 1998;31:1658.