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Noninvasive test for fragile X syndrome, using hair root analysis.

ABSTRACT: Identification of the FMR1 gene and the repeat-amplification mechanism causing fragile X syndrome led to development of reliable DNA-based diagnostic methods, including Southern blot hybridization and PCR. Both methods are performed on DNA isolated from peripheral blood cells and measure the repeat size in FMR1. Using an immunocytochemical technique on blood smears, we recently developed a novel test for identification of patients with fragile X syndrome. This method, also called "antibody test," uses monoclonal antibodies against the FMR1 gene product (FMRP) and is based on absence of FMRP in patients' cells. Here we describe a new diagnostic test to identify male patients with fragile X syndrome, on the basis of lack of FMRP in their hair roots. Expression of FMRP in hair roots was studied by use of an FMRP-specific antibody test, and the percentage of FMRP-expressing hair roots in controls and in male fragile X patients was determined. Control individuals showed clear expression of FMRP in nearly every hair root, whereas male fragile X patients lacked expression of FMRP in almost all their hair roots. Mentally retarded female patients with a full mutation showed FMRP expression in only some of their hair roots (<55%), and no overlap with normal female controls was observed. The advantages of this test are (1) plucking of hair follicles does no appreciable harm to the mentally retarded patient, (2) hairs can be sent in a simple envelope to a diagnostic center, and (3) the result of the test is available within 5 h of plucking. In addition, this test enabled us to identify two fragile X patients who did not show the full mutation by analysis of DNA isolated from blood cells.

SUBMITTER: Willemsen R

PROVIDER: S-EPMC1378079 | biostudies-other | 1999 Jul

REPOSITORIES: biostudies-other

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Noninvasive test for fragile X syndrome, using hair root analysis.

Willemsen R R Anar B B De Diego Otero Y Y de Vries B B BB Hilhorst-Hofstee Y Y Smits A A van Looveren E E Willems P J PJ Galjaard H H Oostra B A BA

American journal of human genetics 19990701 1

Identification of the FMR1 gene and the repeat-amplification mechanism causing fragile X syndrome led to development of reliable DNA-based diagnostic methods, including Southern blot hybridization and PCR. Both methods are performed on DNA isolated from peripheral blood cells and measure the repeat size in FMR1. Using an immunocytochemical technique on blood smears, we recently developed a novel test for identification of patients with fragile X syndrome. This method, also called "antibody test, ...[more]

PMID: 10364521

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Project description:BACKGROUNDCurrent clinical management of patients with pulmonary nodules involves either repeated low-dose CT (LDCT)/CT scans or invasive procedures, yet causes significant patient misclassification. An accurate noninvasive test is needed to identify malignant nodules and reduce unnecessary invasive tests.METHODWe developed a diagnostic model based on targeted DNA methylation sequencing of 389 pulmonary nodule patients' plasma samples and then validation in 140 plasma samples independently. We tested the model in different stages and subtypes of pulmonary nodules.RESULTSA 100-feature model was developed and validated for pulmonary nodule diagnosis; the model achieved a receiver operating characteristic curve-AUC (ROC-AUC) of 0.843 on 140 independent validation samples, with an accuracy of 0.800. The performance was well maintained in (a) a 6 to 20 mm size subgroup (n = 100), with a sensitivity of 1.000 and adjusted negative predictive value (NPV) of 1.000 at 10% prevalence; (b) stage I malignancy (n = 90), with a sensitivity of 0.971; (c) different nodule types: solid nodules (n = 78) with a sensitivity of 1.000 and adjusted NPV of 1.000, part-solid nodules (n = 75) with a sensitivity of 0.947 and adjusted NPV of 0.983, and ground-glass nodules (n = 67) with a sensitivity of 0.964 and adjusted NPV of 0.989 at 10% prevalence. This methylation test, called PulmoSeek, outperformed PET-CT and 2 clinical prediction models (Mayo Clinic and Veterans Affairs) in discriminating malignant pulmonary nodules from benign ones.CONCLUSIONThis study suggests that the blood-based DNA methylation model may provide a better test for classifying pulmonary nodules, which could help facilitate the accurate diagnosis of early stage lung cancer from pulmonary nodule patients and guide clinical decisions.FUNDINGThe National Key Research and Development Program of China; Science and Technology Planning Project of Guangdong Province; The National Natural Science Foundation of China National.

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Noninvasive test for fragile X syndrome, using hair root analysis.

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Noninvasive test for fragile X syndrome, using hair root analysis.

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