Abstract
The index case was referred at 25 weeks to another center because of severe oligohydramnios. Post amnioinfusion, female external genitalia, dolichocephaly, renal agenesis (inferred from absent bladder filling), and severe IUGR led the perinatologist to suggest elective termination. Postmortem, dysmorphologic evaluation revealed dolichocephaly, asymmetric IUGR, a significant nuchal cyst, downward-slanting palpebral fissures, missing 5th ulnar ray of one hand with ulnar deviation of metacarpals, toes “cupped” dorsally, 1st and 5th (and 6th of one foot) most dorsal, female external genitalia, clitoris mildly prominent. Internal examination revealed no cerebral gyrae, bilateral unilobular lungs, membranous VSD, discoid adrenals, renal agenesis, phenotypic “ovaries” unusual in placement—high and attached to lateral pelvic wall, uterus and fallopian tubes absent. Karyotype revealed 46,XY. In spite of the rare and possibly unique occurrence of oligodactyly (absent 5th finger), a clinical diagnosis of SLO was made, and the family counseled. They elected to have detailed ultrasonography in the next pregnancy. At 10 weeks gestation both kidneys were visualized, nuchal cyst was not present, and normal growth documented. At 11 w3d, 20 digits were counted, and ultrasound at 13 weeks revealed a normal number of phalanges in both hands and feet. Gas chromatography from a formalin-fixed specimen from their affected fetus revealed 7-dehydrocholesterol /Cholesterol ratio percent of 443, a markedly increased ratio of 7-dehydrocholesterol to cholesterol, consistent with the diagnosis of SLO. Normal appearing male genitalia were seen at 16 weeks; triple screen drawn then revealed a uE3 level of 0.64 ng/ml, 0.85 MOM. In the Baltimore experience, no affected fetus has had a uE3 higher than 0.65 MOM, and the more severe cases had significantly lower MOM values. The patient subsequently delivered a healthy male infant. The early ultrasound evaluation greatly alleviated the patient's level of anxiety.
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Roberts, R., Kelleys, R. An unusual case of Smith-Lemli-Opitz syndrome and first trimester ultrasonographic exclusion in a subsequent pregnancy. Genet Med 1, 62 (1999). https://doi.org/10.1097/00125817-199901000-00085
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DOI: https://doi.org/10.1097/00125817-199901000-00085