Maternal serum screening abnormality in a fetus associated with arthrogryposis multiplex congenita and amyoplasia

In this journal, Rijhsinghani et al. (1997) reported the observation of positive maternal serum screening tests for Down syndrome in two fetuses affected by spinal muscular atrophy (SMA), an inherited disorder of anterior horn cells. Both cases had elevated maternal serum human chorionic gonadotrophin (hCG) and low unconjugated oestriol (uE3). The authors concluded that the elevated hCG could be related to placental oedema but the low uE3 was difficult to explain. We would like to report our observation of a positive maternal serum screening test for Down syndrome in a fetus affected by arthrogryposis multiplex congenita (AMC) and amyoplasia. A healthy 34-year-old gravida 3, para 2 woman was referred for genetic amniocentesis because of an abnormal maternal serum result which showed a Down syndrome risk of 1:130 calculated from the gestational age, maternal age, maternal serum á-fetoprotein (AFP) of 0·75 multiples of the median (MOM), and free â-hCG of 2·46 MOM at 16 weeks’ gestation. The mother had had a previous preterm child who died of prematurity and also a healthy child. There was no family history of anomalies. Diagnostic amniocentesis revealed a 46,XY karyotype. Sonographic examinations throughout the pregnancy showed normal fetal morphology and growth parameters, but lack of fetal movements was noted. Polyhydramnios accumulated during the third trimester. At 36 weeks’ gestation, an asphyxiated male baby was delivered by Caesarean section. At birth, the infant showed clinical symptoms and signs compatible with the diagnosis of AMC due to amyoplasia. Diagnostic findings included a round face with midline capillary haemangioma; facial asymmetry; a flat nose; hypertelorism; cleft palate; micrognathia; internally rotated shoulders; symmetrical contractures with extended elbows; flexed wrists and equinovarus feet; marked hypoplasia of limb muscles; lack of creases at the palms, soles, elbows, and knees; cryptorchidism; and patent ductus arteriosus. The placenta was normal on gross examination. The infant died of pulmonary hypoplasia 3 days after birth. The parents declined a postmortem evaluation. AMC is a descriptive term referring to a very heterogeneous group of conditions with nonprogressive multiple congenital joint contractures due to congenital myopathy, neuropathy, abnormal connective tissues, limitation of intrauterine space, and/or maternal illness (Hall, 1997). Amyoplasia is the most common condition associated with AMC. Its occurrence has been sporadic. The disorder is probably caused by intrauterine vascular insults on anterior horn cells in the developing fetal spinal cord during the midtrimester (Hall, 1997; Jones, 1997). The present observation and that reported by Rijhsinghani et al. (1997) suggest an association between some neuromuscular disorders and positive maternal serum screening results. However, such associations can be coincidental and further cases will be necessary for proof. We suggest that abnormal serum screening results should prompt sonographic examination for fetal akinesia and arthrogryposis, which are recognizable intrauterine manifestations of neuromuscular disorders.