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Table 1 Revised classification criteria for the antiphospholipid syndrome

From: Double seronegative myasthenia gravis with antiphospholipid syndrome: a case report

Antiphospholipid syndrome is present if at least one of the clinical criteria and one of the laboratory criteria that follow are met*
CC1. Vascular thrombosis One or more clinical episodes of arterial, venous, or small vessel thrombosis, in any tissue or organ**
CC2. Pregnancy morbidity a) One or more unexplained deaths of a morphologically normal fetus at or beyond the 10th week of gestation, with normal fetal morphology documented by ultrasound or by direct examination of the fetus, or
b) One or more premature births of a morphologically normal neonate before the 34th week of gestation because of: (i) eclampsia or severe preeclampsia, or (ii) recognized features of placental insufficiency, or
c) Three or more unexplained consecutive spontaneous abortions before the 10th week of gestation, with maternal anatomic or hormonal abnormalities and paternal and maternal chromosomal causes excluded
LC1. Lupus anticoagulant present in plasma on two or more occasions at least 12 weeks apart
LC2. Anticardiolipin antibody Of IgG and/or IgM isotype in serum or plasma present in medium or high titer (i.e. >40GPL or MPL, or > the 99th percentile), on two or more occasions at least 12 weeks apart
LC3. Anti-β2 glycoprotein-I antibody Of IgG and/or IgM isotype in serum or plasma (in titer > the 99th percentile), on two or more occasions at least 12 weeks apart
  1. Abbreviations: CC, clinical criteria; Ig, immunoglobulin; GPL, IgG phospholipid units; LC, laboratory criteria; MPL, IgM phospholipid units.
  2. *Classification of antiphospholipid syndrome should be avoided if less than 12 weeks or more than 5 years separate the positive antiphospholipid test and the clinical manifestation.
  3. **Thrombosis must be confirmed by objective validated criteria (that is, unequivocal findings of appropriate imaging studies or histopathology). For histopathologic confirmation, thrombosis should be present without significant evidence of inflammation in the vessel wall. Antiphospholipid syndrome categories: I: more than one laboratory criterion present (any combination); IIa: lupus anticoagulant present alone; IIb: anticardiolipin antibody present alone; IIc: anti-β2 glycoprotein-I antibody present alone.