Objective: To describe the prenatal diagnosis of trichothiodystrophy (TTD)
through endoscopically-guided fetal eyebrow biopsy. Materials and Methods:
A 32-year old patient, gravida 4, para 3, with a history of 2 previous infa
nts affected with TTD was referred at 17 (5)/(7) weeks for fetal hair biops
y. DNA repair studies had been normal in the previous children. Four l-mm b
iopsies were obtained from the external aspect of the fetal eyebrows under
direct endoscopic guidance. Fetal hair samples were assessed with polarized
microscopy, electron microscopy, hematoxylin and eosin staining, and were
also sent for analysis of sulfur content (cystine levels). Results: The fet
al eyebrows were the only adequate source of hair in the early second trime
ster. The biopsy samples yielded adequate material for all tests. Polarized
microscopy showed characteristic banding patterns, but trichoschisis was n
ot apparent. Cystine levels (19 mu mol/l) in the biopsy sample were signifi
cantly lower than an age-matched (fresh spontaneous abortion) control (368
mu mol/l). Conclusion: Prenatal diagnosis of TTD is possible in the second
trimester through endoscopically-guided eyebrow biopsy. An adequate amount
of hair is present in the eyebrows by then, and the disease is already mani
fest. Analysis of sulfur content of the hair samples is preferred over pola
rized or electron microscopy, as many classic microscopic findings of TTD m
ay not be present in the early second trimester. Copyright (C) 2000 S. Karg
er AG, Basel.