False positive screen test for #mucopolysaccharidoses in healthy #female #newborns.
Monachesi C1, Zampini L1, Padella L1, Marchesiello RL1, Galeazzi T1, Santoro L1, Catassi C1, Gasparrini E2, Carnielli VP3, Volpi N4, Fiumara A5, Concolino D6, Tomanin R7, Coppa GV1, Gabrielli O8.
Abstract
BACKGROUND:
In total, 930 urine samples obtained on 2nd and 3rd day from birth have been analyzed for the early diagnosis of Mucopolysaccharidoses.
METHODS:
Dimethylmethylene blue (DMB) assay and one-dimensional electrophoresis were performed in all urine samples. Agarose gel electrophoresis, before and after treatment with chondroitinase ABC and heparinases, was used for a comprehensive characterization.
RESULTS:
Out of 930 urine samples 7 showed anomalous electrophoretic pattern; 5 of them had high GAG levels by DMB test. Atypical samples (n = 7) were analyzed by agarose gel electrophoresis. After enzymatic digestion, some slow bands were still visible. A second urine sample of the above 7 newborns was analyzed at the age of 1 month, demonstrating both a normal pattern and normal GAG levels. Additional urine and vaginal mucus samples from 10 term neonates with vaginal bleeding showed the same electrophoretic pattern observed in the 7 false positive samples.
CONCLUSIONS:
The altered electrophoretic pattern may be due to the presence of glycoproteins and not to specific GAGs, due to high levels of maternal hormones exposure during pregnancy. To our knowledge, this is the first time maternal estrogen hormones are proposed as a likely cause of false-positive urinary glycosaminoglycan screen test in healthy newborns.
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