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L R Shapiro

Publications and source records attributed to L R Shapiro.

104 records · Page 6Linked to original sources
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DNA-based genetic testing in fifty fragile X families.

During the past 4 years (1985-1989), we have analyzed 171 cases in 50 fragile X [fra(X)] families by DNA linkage methods. Most (140 cases; 81%) were for carrier detection, both female (98 cases; 57%) and male (41 cases; 24%). Women who were obligate carriers of the fra(X) mutation accounted for an additional 6 "prior-to-pregnancy" cases. Four pregnancies have subsequently occurred with 3 having been successfully monitored (one male, 2 females). One pregnancy miscarried early prior to testing. Prenatal diagnoses (26 cases; 15%) accounted for the remainder of cases (15 males, 11 females). These will be discussed in the companion paper by Shapiro et al. (Am J Med Genet, 1991). A diagnosis in the cytogenetically uninformative carrier cases was reached in greater than 75% of analyses with a panel of 5 probes: 3 proximal (F9, DXS105, DXS98) and 2 distal (F8, DSX52). Five additional probes, 3 proximal (DXS10, DSX51, DSX102) and 2 distal (DSX15, DXS33), were used in cases that were resistant to analysis with the standard panel. In 60% of cases, flanking markers were identified (proximal and distal). Given this panel, only 5% of cases did not have any informative markers identified. Thus, molecular methods can provide a useful adjunct to cytogenetic analysis in most situations. An unusual association between the rare allele (A1) of DXS10 with the X chromosome carrying the fra(X) mutation was observed. This occurred in both male and female carriers in the uppermost generation tested. The basis for this association is uncertain at the present time.

Alleles↗
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Cytogenetic diagnosis of the fragile X syndrome: efficiency, utilization, and trends.

In order to assess the impact of the increasing awareness of the fra(X) syndrome and a broader approach to fra(X) testing, we analyzed our laboratory experience for 1980-1988. In 1981-1986, there was an average of 80 cases/year (62 male; 18 female). The 103 (74 male; 29 female) cases in 1987 represent a 45% increase over the prior 3 years; this sustained in 1988 with 106 cases. The fra(X) positive yield decreased from a high of 49% in 1980 to an average of 20% (range 15-24%) in 1981-1984, 10% (range 9-11%), in 1985-1987 and 7% in 1988. The positive rate for males and females was nearly identical in both time periods. The positive yield for mentally retarded individuals with a family history of mental retardation dropped from an average of 20% for 1981-1984 and 33% for 1985-87 to 13% for 1988; however, the positive fra(X) rate for mentally retarded individuals decreased from an average of 23% in 1981-1984 to 9% in 1985-1987 and 7% in 1988. The decreasing fra(X) yield and increasing case load are directly attributable to the relaxation of criteria for referral and testing related to the referral of all mentally retarded patients, and to the perceived malpractice liability for not doing a "complete" evaluation. Although the burden for cytogenetic laboratories is considerable, the yield of positive fra(X) cases is still worthwhile, and may be maximized by the use of improved screening criteria.

Evaluation Studies as Topic↗
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Prenatal diagnosis of the fragile X syndrome: possible end of the experimental phase for amniotic fluid.

We have had experience with 260 prenatal diagnosis cases for the fragile X syndrome [fra(X)]; amniotic fluid was received in 230. There was a documented family history of fra(X) in 148 amniotic fluid cases. Our sample includes 91 males. Eleven were correctly identified as fra(X)-positive and 2 were false-negative. Eight of 57 females were fra(X) positive and one was a false-negative. CVS were received in 21 cases with a family history of fra(X), and there were 2 positive results in females and 3 false-negative results in males which were ultimately detected by means of molecular analysis or a subsequent amniotic fluid specimen. RFLPs were utilized in 29 cases (amniotic fluid and CVS); RFLPs identified 2 false-negative cytogenetic results in CVS. Two male fetuses were found to have a high probability of being affected by means of RFLPs, but on the basis of prenatal and postnatal negative fra(X) cytogenetic results and subsequent normal growth and development, they are either unaffected transmitting males or are double recombinants. Three female fetuses were also found to be cytogenetically negative in CVS but had a 90%, 93%, and 99% probability of being affected by RFLPs. On the basis of the data, it can be concluded: 1. Amniotic fluid experience is adequate to eliminate the "experimental" designation providing the limitations are understood and an experienced laboratory is involved. 2. Chorionic villus cells for cytogenetic analysis should still be considered experimental. 3. Negative results with CVS should be confirmed by molecular methods and/or by cytogenetic analysis of another tissue. 4. Multiple approaches can maximize reliability of fra(X) prenatal diagnosis.

Amniocentesis↗
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Relationship between age and IQ among fragile X males: a multicenter study.

Longitudinal decline in IQ among fragile X males was reported recently. However, there are problems in retesting IQ that may affect scores. Two such factors are intertest time interval and score obtained on the first test. To determine the generality of IQ score changes, we examined 101 fragile X males from 6 centers. To ensure high test-retest reliability, only results from Stanford-Binet and Wechsler tests were used. Thus there were retest scores from 60 subjects. Test-retest reliability between first and last scores was very good (r = 0.85) and comparable to those seen in nonfragile X mentally retarded individuals. Also computed were z-scores of differences in IQ scores. The z-score differences were distributed about a mean at 1 SD below the expected zero value. Eighteen subjects showed statistically significant decreases in IQ, 6 showed statistically significant increases, while 5 showed the same scores. Z-score differences were not correlated with type of residence or elapsed intertest interval, but were negatively correlated with first score obtained, indicating a regression-to-the-mean effect. Using a multiple regression analysis, we found first score obtained, age tested, and age retested significant predictors of score differences, accounting for 19% of the total variance. These results suggest that factors previously identified as affecting retest scores have a smaller effect than originally thought. It is suspected that decline in IQ is associated with dynamic neurological processes and needs to be investigated further.

Adolescent↗
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Longitudinal changes in IQ among fragile X males: clinical evidence of more than one mutation?

Longitudinal changes in IQ among mentally retarded (MR) fragile X [fra(x)] males have been reported previously. While age is associated with decline in IQ, not all males are so affected. This suggests that there may be more than one subtype of affected fra(X) male. Therefore, we examined the distribution of standardized difference scores (Zdiff) in IQ to determine if subjects were from an admixture of at least 2 populations. Cluster analysis of Zdiff scores was used to partition subjects into 2 groups. Goodness-of-fit tests indicated that scores were more likely to come from an admixture. Discriminant functions (DF) were calculated to determine predictive validity of Zdiff scores. To eliminate the effect of skewing, a power transform was applied to Zdiff scores and DFs recomputed. Zdiff and transformed scores provided similar results. The mean and variance for one group showed no differences in test-retest scores as would be expected from examining any population while the mean for the second group indicated significant decline in IQ nearly 4 standard errors below the first test score. These results suggest that there may be clinical evidence for 2 types of fra(X) mutation: One which causes MR but is static, and a second mutation which causes MR but is dynamic and contributes to an apparent longitudinal decline in cognitive function.

Adolescent↗
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Prenatal cytogenetic diagnosis of the fragile X chromosome: feasibility and speed of in situ clonal method in amniotic fluid cell tissue culture.

We have had experience with over 300 amniotic fluid specimens for prenatal diagnosis for the fragile X chromosome [fra(X)], and the flask method of tissue culture has been routinely utilized requiring extended tissue culture periods of 3-4 weeks. The use of the in situ clonal method of tissue culture for routine prenatal cytogenetic diagnosis of amniotic fluid cells has shortened tissue culture time and resulted in more rapid reporting; however, it has not been widely employed for fra(X) prenatal diagnosis. The simultaneous use of both methods of tissue culture has resulted in the detection of 2 cytogenetically fra(X) positive cases in amniotic fluid, with more rapid reporting and satisfactory expression of the fra(X) with the in situ clonal method. Thus, the use of the in situ clonal method of tissue culture for fra(X) prenatal diagnosis in amniotic fluid cells is feasible, faster and can serve as a more rapid cytogenetic adjunct to the newer DNA testing methods.

Amniotic Fluid↗
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Prenatal cytogenetic diagnosis of the fragile X syndrome in amniotic fluid: calculation of accuracy.

We have completed over 350 prenatal diagnoses for the fragile X [fra(X)] syndrome using amniotic fluid, chorion villus specimen (CVS), fetal blood sampling and molecular methods. A total of 300 amniotic fluid specimens have been received for prenatal diagnosis of the fra(X) syndrome. There was a documented family history of fra(X) in 170/300 amniotic fluid cases, and 23/170 were correctly identified as cytogenetically fra(X) positive (16 male; 7 female). Three males were false-negative, and one female was fra(X) negative but identified as a probable carrier by RFLPs. No fra(X) positive or false-negative results were found in the absence of a fra(X) family history. Because the a priori risk for the fra(X) syndrome for each pregnancy was different and widely variable, the determination of the accuracy of the prenatal diagnosis results requires a consideration of these variables. On this basis, the calculated accuracy of prenatal cytogenetic diagnosis for the fra(X) syndrome is approximately 97%. This accuracy can be improved further with the simultaneous use of molecular methods, especially in view of recent developments.

Cytogenetics↗
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Prenatal diagnosis of fragile X syndrome: results from parallel molecular and cytogenetic studies.

Since 1985, we have provided coordinated DNA-based and cytogenetic prenatal analysis for couples at risk for offspring afflicted with the fragile X [fra(X)] syndrome. To date, 40 pregnancies have been studied (22 males, 18 females). There were 5 males and 3 females identified to be at high risk by DNA but only 2 males and one female were demonstrated to be cytogenetically expressing the fra(X) prenatally. Of the other 3 males, one was a cytogenetic false negative (i.e. confirmed fra(X)+ at termination of pregnancy). The other 2 remain fra(X)- and are developing normally (undetected recombinants or non-penetrant male carriers). All fetuses at low risk were carried to term and are reported to be normal.

Cytogenetics↗
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Immediate and unexplained fetal death during mid-trimester amniocentesis.

Immediate and unexplained fetal death during mid-trimester amniocentesis for prenatal diagnosis was found to be an uncommon though real phenomenon. A survey of programmes in the United States detected 5 cases from 7524 at 4 centres. Postmortem examination was not helpful and a neurogenic mechanism is postulated. Awareness of this phenomenon and routine pre- and post-amniocentesis ultrasound monitoring may clarify the actual prevalence and etiology.

Adult↗
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Pericentric inversion of the Y chromosome and prenatal diagnosis.

Pericentric inversion of the human Y chromosome has been estimated to occur with a frequency of 1-2 per thousand in various populations, and the results of this study, derived from over 12 000 prenatal diagnosis cases, is 1.15 per 1000. In these cases, it was concluded that there was no clinical significance because the fathers and male fetuses had the same pericentric inversion. Chromosome analysis of the father is advisable to determine whether or not the inversion is familial in order to be able to provide genetic counselling.

Chromosome Inversion↗
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The effects of a cost-education program on hospital charges.

An educational intervention designed to change physicians' use of inpatient services was implemented on two general medical services for a year. The intervention consisted of a brief orientation to cost containment issues, a pamphlet that outlined practical cost containment strategies and listed the charges for commonly ordered tests and services, and access to detailed interim patients' bills generated during the hospitalization. Two concurrent control services received no intervention. Over 1,600 admissions were evaluated. The geometric mean length of stay was 0.61 days shorter on intervention services compared with control (5.15 vs. 5.76 days, p less than 0.01). The geometric mean hospital charges were $388 less for intervention patients ($3,199 vs. $3,587, p less than 0.005). Neither patients' demographic characteristics nor case mix could explain the reductions. The authors conclude that a simple program utilizing information already in existence in most hospitals can result in a significant and meaningful reduction in length of stay and charges.

Cost Control↗