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Biomedical subjects

W R Breg

Publications and source records attributed to W R Breg.

At least 91 records · Page 5Linked to original sources
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Aneuploidy and the fragile X syndrome.

The possibility that female carriers of the fragile X gene(s) are at increased risk for nondisjunctional events leading to aneuploid offspring has been suggested by several investigators. To better address this question we analyzed pedigrees of 117 families in which the fragile X syndrome is segregating. The 117 pedigrees, originally collected for segregation analyses, included 236 females with offspring whose carrier status was determined by cytogenetic or pedigree analysis or by analyses using flanking DNA markers. These 236 females have had 931 offspring including one 47,XXY and 6 trisomy 21 individuals (1/155). Statistical analysis suggested that the observed rate of trisomy 21 was significantly higher than expected (Fisher's exact test, p less than or equal to 0.05). Assuming a Poisson distribution to calculate the confidence interval for the observed rate of trisomy 21 individuals, we found that the expected rate of 1.6/1000 in this sample fell outside the 99% confidence limits of our observed rate of 1/155. Additional data from a larger sample are needed to replicate these findings.

Aneuploidy↗
PubMedDate not supplied

Experience with multiple approaches to the prenatal diagnosis of the fragile X syndrome: amniotic fluid, chorionic villi, fetal blood and molecular methods.

We have had experience with 160 prenatal diagnosis cases for the fragile X syndrome [fra(X)] or Martin-Bell Syndrome. In 140, amniotic fluid was utilized; 98 had a documented family history of fra(X). The 94 completed cases included 4 no growth; 56 males of which 7 were fra(X)-positive and 2 false-negative; 38 females of which 5 were fra(X) positive. There was no fra(X) positive result when a family history of mental retardation was not documented as fra(X). Molecular methods (RFLPs) were utilized in 10 amniotic fluid and 5 chorionic villus specimens (CVS). Percutaneous umbilical blood sampling was used in 2 negative cases and 1 fra(X) positive case because of timing, tissue culture failure or confirmation of another method. CVS were received in 13 cases, and RFLPs were utilized in 5 of the CVS cases. There was no positive fra(X) CVS chromosome result in males, 1 positive result in a female, but 2 false negatives were detected by RFLPs. On the basis of the results, it can be concluded that cytogenetic and molecular methods are complementary and best used together and that multiple approaches can enhance the efficiency and reliability of fra(X) prenatal diagnosis.

Amniocentesis↗
PubMedDate not supplied

Anthropometric comparison of mentally retarded males with and without the fragile X syndrome.

An anthropometric survey of 41 variables (weight, height, 10 linear, 4 breadth, 22 craniofacial, 2 skinfold, and testicular volume), including multivariate discriminant analysis, was undertaken on 110 mentally retarded males (39 with and 71 without the fra(X) syndrome). The mean Z scores of the fra(X) syndrome males fell between -2.00 and 8.38 for bizygomatic diameter and testicular volume, respectively, and the range of the mean Z scores of the non-fra(X) males was from -2.64 to 2.26 for hand breadth and testicular volume, respectively. There was a statistically significant difference (P less than .05) between fra(X) and non-fra(X) males for 18 measurements (weight, height, 7 linear, 2 breadth, 5 craniofacial, 1 skinfold, and testicular volume), with the greater measurements (excluding bizygomatic diameter) found in fra(X) males. Sitting height, knee-buttock length, middle finger length, and hand length were negatively correlated (P less than .05) with age, whereas bizygomatic diameter, ear length, and ear width were positively correlated (P less than .05) with age and head circumference, head length, and outer canthal distance were positively correlated (P less than .05) with fra(X) chromosome expression in the fra(X) males. Triceps and subscapular skinfold thicknesses were negatively correlated (P less than .05) with age, whereas ankle breadth, ear length, ear width, and nose length were positively correlated (P less than .05) in the non-fra(X) males. Discriminant analysis of 34 fra(X) and 71 non-fra(X) males resulted in a discriminant function based on 6 of 17 anthropometric variables and age.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗