Increased sister chromatid exchange frequency at Xq27 site in affected fragile X males.

Sister chromatid exchange (SCE) was evaluated in peripheral blood lymphocytes cultured from normal subjects, fragile X carrier females, and fragile X affected males and in general did not differ among all subjects whether cells were grown in thymidine-deficient or complete medium. However, at the Xq27 site, SCE was significantly increased for fragile X affected males, particularly in cells grown in thymidine-deficient medium.

Obesity in achondroplasia.

Obesity is a significant and potentially serious health problem in achondroplasia. Body mass indices, weight-to-square of the height ratio (W/H2), and triceps skinfold measurements show that obesity is common. It begins in early childhood and is prevalent at all ages. We recommend that weight be monitored closely in all persons with achondroplasia and that dietary intervention be instituted whenever the body mass indices, W/H2, and triceps skinfold measurements exceed the 95th centile for the general population.

Job patterns of disabled beneficiaries.

This article presents basic findings about the job patterns of disabled-worker beneficiaries covered under the Social Security Administration Disability Insurance (DI) program as reported in the New Beneficiary Follow-up survey. Beneficiaries are asked retrospective questions about labor-force participation from the time of their first entitlement to disability benefits to the time of the interview. Twelve percent of those persons who enter the DI program as nonworking beneficiaries start a job during their entitlement to benefits. The mean time to the start of the job was 3.4 years. Of those who start a job, 50 percent end the job before the end of their entitlement. Most of these persons leave the job for health-related reasons and, for most of them, the employer does not play a major role in their decision to stop working. For those who end the first job and are employed in subsequent jobs, the percentage who recover while still in the job decreases as the number of jobs increases.

Factors affecting the work efforts of disabled-worker beneficiaries.

Congress is currently placing considerable emphasis on returning disabled-worker beneficiaries to work. However, going back to work is only the first step in the complex process of program termination due to work and trust fund savings. Not only must the beneficiary get a job, but also the work effort must be sustained at what is considered a substantial gainful activity (SGA) level by the disability program (so that an SGA termination will result) and a reasonable living condition must be achieved by the beneficiary (so that the person is motivated to continue working and lose benefits). This article focuses on those factors that affect the ability of the beneficiary to sustain such a work effort. Combined with previous findings about returning to work, we begin to see the overall effect of the factors on work efforts. Beneficiaries who have physical therapy rehabilitation have a higher tendency to start working and a lower tendency to stop. Those with vocational training or general education have a higher tendency to start working, but these factors do not help to sustain the effort. Beneficiaries who were helped with job placement have a higher tendency to start work, but they also have a higher tendency to stop. If beneficiaries knew about the trial-work period, but not about either the extended period of eligibility or Medicare continuation, then they had a higher tendency to start work and a higher tendency to stop. However, if they knew about all three work-incentive provisions, then the tendency to work was not affected.

A comparison of the recovery termination rates of disabled-worker beneficiaries entitled in 1972 and 1985.

This article reports on the final phase of a longitudinal analysis of two cohorts of Disability Insurance (DI) beneficiaries. The analysis shows that changes in DI program provisions and demographic shifts in the beneficiary population have considerably affected standard recovery termination rates. Several covariates were also found to affect the rates, particularly age and education. Overall, the 1985 cohort has a lower standard recovery termination tendency during the first few years of entitlement. After an attempt was made to define a recovery event for the 1985 cohort to make it comparable to the 1972 cohort, it was found that the termination rate for the 1985 cohort was still lower than the termination rate for the 1972 cohort. These findings suggest that there will be fewer recoveries for beneficiaries who entered the DI program in the late 1980's than for those who came on the rolls earlier.

Comparison of individual characteristics and death rates of disabled-worker beneficiaries entitled in 1972 and 1985.

The many changes to the Disability Insurance (DI) program that took place during the early 1980's suggest that there may be significant differences in the characteristics of newly awarded beneficiaries over time. This study compares two cohorts of newly entitled beneficiaries--one from 1972 and the other from 1985--in order to assess changes in individual characteristics and death rates between the pre-1980's and the late 1980's. The 1985 cohort had a greater percentage of beneficiaries with mental impairments and a lower percentage with diseases of the circulatory system. The 1985 cohort was also younger, more educated, had higher primary insurance amount levels, and had greater percentages of women and black beneficiaries. Although the death rates and survival curves for both cohorts were very similar, differences in the curves occurred for some covariate subgroups. When the populations were standardized, the estimated percentages of beneficiaries who survived 5 years after entitlement were 78 percent for the 1972 cohort and 77 percent for the 1985 cohort.

The effect of vocational rehabilitation and work incentives on helping the disabled-worker beneficiary back to work.

This article is the second in a series of articles that use data from the New Beneficiary Followup survey to analyze the work efforts of the Social Security Administration's Disability Insurance beneficiaries. Survival analysis techniques are used to determine the effect of vocational rehabilitation efforts and work incentive program provisions on actual work outcomes. The findings indicate that the demographic variables of age, gender, race, education, and marital status affect the tendency to return to work in the expected way. The results suggest a possible disincentive effect may be built into certain work incentive provisions of the program. The encouraging news is that the vocational rehabilitation efforts seem to have a positive effect on the tendency to return to work. Physical therapy, vocational training, general education, and job placement efforts all seem to increase the tendency to go back to work.

Work efforts of disabled-worker beneficiaries: preliminary findings from the new beneficiary followup survey.

This article represents a preliminary investigation of factors influencing the decision of disabled-worker beneficiaries to look for employment and to return to work. Using the New Beneficiary Followup Survey and the special add-on frame of beneficiaries who had earnings, the article analyzes the impact of vocational rehabilitation (VR), work incentives, and employer workplace accommodations on the decision to return to work. Also examined are the reasons beneficiaries gave for deciding to look for work, job search methods, and the types of jobs that they were looking for. The research indicates that most beneficiaries look for work for financial reasons, for example, out of economic necessity or to improve their standard of living. Only 1 in 4 reported that they had received VR services and most indicated that it did not help them on the job. Most beneficiaries (80 percent) were unaware of work incentive provisions at the time they returned to work. Nearly half (42 percent) reported receiving workplace accommodations from their employer. Further research is planned to help assess the return to work experience.

Effect of substantial gainful activity level on disabled beneficiary work patterns.

Analysis of disabled beneficiaries' earnings records from the 1-percent Continuous Work History Sample over a 15-year period indicates that increases in the substantial gainful activity (SGA) level in 1966, 1968, and 1974 were not followed by incremental increases in beneficiary earnings. This article examines the flow of disabled-worker beneficiaries through the disability program in relation to their work history and earnings patterns. The recovery rate dropped steadily during the late 1960's and early 1970's. The earnings patterns indicate that about 10 percent of the beneficiaries were employed; about 3 percent had earnings above the SGA level. Median annual earnings remained well below $1,000, whatever the SGA level. Findings of the study suggest that policy considerations on changing the SGA level should not center on the implications for marginal part-time employment. Most of the evidence from beneficiary work and earnings patterns indicates that the SGA level has not operated as an effective work incentive. The program-flow analysis suggests that the allowance process rather than termination of benefits for recovery after sustained work holds the key to controlling program growth.

Postrecovery experience of disabled-worker beneficiaries.

This study followed a 1972 cohort of newly entitled beneficiaries from January 1, 1981, when they left the Disability Insurance program because of a recovery, to June 1986. This recovery group represents about 11 percent of the cohort of disabled-worker beneficiaries entitled in 1972. Three outcomes or next events were of specific interest: Return to the DI program, death, and attaining age 62 (considered retirement for the purposes of this study). The tendency toward reentitlement and the tendency toward death were modeled and then combined with retirement age to project the percentages of recovered beneficiaries who end the postrecovery period by reentitlement, death, or retirement. About 43 percent of these recovered beneficiaries are expected to become reentitled some time after leaving the program, and 52 percent are expected to reach retirement age before dying or becoming reentitled. Of the 43 percent projected too return to the program, 23 percent are expected to become reentitled within the first 5 years of recovery. The tendency to return to the DI program drops sharply at the fifth year of the postrecovery period. There may be program-based reasons for this pattern. The Social Security Amendments of 1980 may provide incentives to return to the DI program within 5 years. When covariates were examined, the covariate PIA had a strong effect on the reentitlement tendency. For those in the high PIA group ($500 or more), it is projected that 65 percent will return to the DI program. This projection is considerably higher than the 34 percent projection for those in the low PIA group (less than $500). Projected median time to reentitlement is quite different for the two PIA groups. The median time to reentitlement is 10 years for the low PIA group and only 3 years for the high PIA group. The PIA was also important in modeling the death tendency as the next event in the postrecovery period. For those in the low PIA group, death is the next event projected for 3 percent of the individuals; in the high PIA group, the projected proportion is 11 percent. It is suspected that the PIA may be acting as a proxy for the severity of the disabling condition, but this hypothesis cannot be tested with the available data. These descriptions of the reentitlement and death tendencies and the project percentages provide a global picture of the DI program reentitlement process. Further research will continue by comparing this pre-1980's cohort with a later cohort and studying the causal mechanisms underlying the recovery and reentitlement processes.

Rhodopsin mutations in autosomal dominant retinitis pigmentosa.

DNA samples from 161 unrelated patients with autosomal dominant retinitis pigmentosa were screened for point mutations in the rhodopsin gene by using the polymerase chain reaction and denaturing gradient gel electrophoresis. Thirty-nine patients were found to carry 1 of 13 different point mutations at 12 amino acid positions. The presence or absence of the mutations correlated with the presence or absence of retinitis pigmentosa in 174 out of 179 individuals tested in 17 families. The mutations were absent from 118 control subjects with normal vision.

Identification of novel rhodopsin mutations responsible for retinitis pigmentosa: implications for the structure and function of rhodopsin.

Ten rhodopsin mutations have been found in a screen of 282 subjects with retinitis pigmentosa (RP), 76 subjects with Leber congenital amaurosis, and 3 subjects with congenital stationary night blindness. Eight of these mutations (gly51-to-ala, val104-to-ile, gly106-to-arg, arg135-to-gly, cys140-to-ser, gly188-to-glu, val209-to-met, and his211-to-arg) produce amino acid substitutions, one (gln64-to-ter) introduces a stop codon, and one changes a guanosine in the intron 4 consensus splice donor sequence to thymidine. Cosegregation of RP with gln64-to-ter, gly106-to-arg, arg135-to-gly, cys140-to-ser, gly188-to-glu, his211-to-arg, and the splice site guanosine-to-thymidine indicates that these mutations are likely to cause retinal disease. Val104-to-ile does not cosegregate and is therefore unlikely to be related to retinal disease. The relevance of gly51-to-ala and val209-to-met remains to be determined. The finding of gln64-to-ter in a family with autosomal dominant RP is in contrast to a recent report of a recessive disease phenotype associated with the rhodopsin mutation glu249-to-ter. In the present screen, all of the mutations that cosegregate with retinal disease were found among patients with RP. The mutations described here bring to 35 the total number of amino acid substitutions identified thus far in rhodopsin that are associated with RP. The distribution of the substitutions along the polypeptide chain is significantly nonrandom: 63% of the substitutions involve those 19% of amino acids that are identical among vertebrate visual pigments sequenced to date.