Background: The foetal Arthrogryposis multiplex congenita is defined as the occurrence of malposition
of two joints in at least two body regions. This descriptive definition comprises
a multitude of genetic and non-genetic causes. The detection of the underlying aetiology
is reported to be approximately 5%. A rare non-genetic cause of foetal Arthrogryposis
is a maternal myasthenia gravis or maternal autoantibodies against the Acetylcholine-Receptor
(AChR-AA). By passing the placenta, they cause foetal akinesia deformation sequence.
Case report: A healthy 28-year-old primigravida presents in 13 weeks of gestation for first trimester
screening. A cystic hygroma is detected and chorionic villous sampling is performed
yielding a normal fetal karyotype. In the 16 weeks scan, a fixed extension in the
knee joints, a fixed flexion in the elbow joint is detected. In 21 weeks the patient
is referred with hydrops fetalis and massive skin oedema. The liver function tests
were abnormal and pregnancy was terminated due to impending mirror syndrome. Six months
later the patient presents with a new pregnancy. The first trimester- as well as 16
weeks scan were uneventful. In the 22 weeks scan, the fetus exhibited extended legs,
talipes on both sides, fixed flexion in the elbow joints, retrognathia and polyhydramnios.
The karyotype was normal. A genetic counselling was performed and maternal AChR-AA
were determined, which were elevated 40x above normal. Due to progressive fetal akinesia
including thorax deformation, pregnancy was terminated.
Conclusion: Maternal AChR-AA constitute a rare cause of fetal Arthrogryposis, also in the absence
of symptoms of myasthenia gravis in the pregnant mother. By passing the placenta,
they cause foetal akinesia deformation sequence. Differential diagnostic workup, especially
in recurrent cases, should include their evaluation. Knowledge about their presence
allows for diagnostic intervention such as plasmapheresis before the subsequent pregnancy.
