Fetal akinesia deformation sequence

Fetal akinesia deformation sequence (FADS), also known as Pena-Shokeir syndrome type I, is a rare and severe condition characterized by decreased or absent fetal movement (akinesia) during pregnancy, which leads to a cascade of secondary developmental abnormalities. The lack of fetal movement results in multiple joint contractures (arthrogryposis), intrauterine growth restriction, pulmonary hypoplasia (underdeveloped lungs), short umbilical cord, and polyhydramnios (excess amniotic fluid). Facial anomalies are common and may include micrognathia (small jaw), hypertelorism (widely spaced eyes), low-set ears, and a depressed nasal tip. The condition affects multiple body systems, including the musculoskeletal, respiratory, neurological, and craniofacial systems. FADS is a clinically and genetically heterogeneous condition. It can result from any process that impairs fetal movement, including primary neuromuscular disorders (affecting the brain, spinal cord, peripheral nerves, neuromuscular junction, or muscles), connective tissue abnormalities, or restricted fetal space. Numerous genes have been implicated, including DOK7, RAPSN, MUSK, NUP88, and genes encoding acetylcholine receptor subunits (CHRNA1, CHRND, CHRNG), among others. Both autosomal recessive and, less commonly, autosomal dominant and X-linked inheritance patterns have been described, depending on the underlying genetic cause. The prognosis for FADS is generally very poor. Many affected pregnancies result in stillbirth, and most liveborn infants die in the neonatal period, primarily due to pulmonary hypoplasia and respiratory failure. There is no curative treatment; management is supportive and palliative. Prenatal diagnosis is possible through ultrasound detection of decreased fetal movements, joint contractures, and associated anomalies, and genetic testing can help identify the underlying cause for recurrence risk counseling. Families affected by FADS benefit from genetic counseling to understand the specific inheritance pattern and recurrence risk in their case.

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