A girl with a G22 ring chromosome is described. There are few physical abnormalities, performance quotient is in the low normal range but verbal skills are much retarded. (+info)
Feasibility and acceptance of screening for fragile X mutations in low-risk pregnancies.
(10/2787)
Fragile X syndrome is the second leading cause of mental retardation after Down syndrome. Most women carriers of the fragile X mutation are unaware of their condition. We critically evaluated whether screening pregnant women at low risk for FMR1 mutation would be feasible as a routine part of antenatal care in general practice. We also studied acceptance and attitudes to gene testing. From July 1995 until December 1996, a carrier test was offered at the Kuopio City Health Centre free of charge to all pregnant women in the first trimester following counselling given by midwives on fragile X syndrome. All women found to be carriers of FMR1 gene mutations underwent detailed genetic counselling and were offered prenatal testing. Attitudes towards the gene test were elicited by questionnaire. Most pregnant women (85%) elected to undertake the gene test. Six women were found to be carriers (a rate of 1 in 246), and all subsequently accepted prenatal testing. Three foetuses had a normal FMR1 gene, one had a large premutation, one a 'size mosaic' mutation pattern, and another a full mutation. This observational and interventional study demonstrates that antenatal screening provides an effective way of identifying carriers and incorporating prenatal testing into this process. (+info)
Side effects of extinction: prevalence of bursting and aggression during the treatment of self-injurious behavior.
(11/2787)
Findings from basic and applied research suggest that treatment with operant extinction may produce adverse side effects; two of these commonly noted are an increase in the frequency of the target response (extinction burst) and an increase in aggression (extinction-induced aggression). Although extinction is often used to treat problem behavior in clinical settings, few applied studies have examined the prevalence of these side effects or their possible attenuation with other operant procedures. An analysis of 41 data sets for individuals who received treatment for self-injurious behavior indicated that extinction bursts or increases in aggression occurred in nearly one half of the cases. The prevalence of bursting and aggression was substantially lower when extinction was implemented as part of a treatment package rather than as the sole intervention. (+info)
Reduction of stimulus overselectivity with nonverbal differential observing responses.
(12/2787)
Three individuals with mental retardation exhibited stimulus overselectivity in a delayed matching-to-sample task in which two sample stimuli were displayed on each trial. Intermediate accuracy scores indicated that participants could match one of the samples but not both of them. Accuracy in a baseline condition was compared to accuracy with a differential observing response procedure. This procedure prompted participants to make simultaneous identity-matching responses that required observation and discrimination of both sample stimuli. These observing responses were never followed by differential consequences. When observing responses were prompted, participants' accuracy scores improved. In a return to the baseline condition, when differential observing responses were no longer prompted, accuracy returned to intermediate levels. The results show that stimulus overselectivity can be greatly reduced by a behavioral intervention that controls observing behavior and verifies discrimination, but that exposure to such procedures alone may be insufficient for lasting benefits. (+info)
Clarifying an ambiguous functional analysis with matched and mismatched extinction procedures.
(13/2787)
Results of functional analysis were ambiguous in suggesting that self-injurious behavior (SIB) was maintained by escape, sensory reinforcement, or both. To help clarify these results, we compared escape extinction, sensory extinction, and the combined treatments. Sensory extinction proved to be a necessary and sufficient treatment, whereas escape extinction failed to decrease SIB. These analyses helped to clarify the function of SIB and to identify an effective and efficient treatment. (+info)
Evaluation of a mutation screening strategy for sporadic cases of ATR-X syndrome.
(14/2787)
We report on the evaluation of a strategy for screening for XNP/ATR-X mutations in males with mental retardation and associated dysmorphology. Because nearly half of the mutations in this gene reported to date fall into a short 300 bp region of the transcript, we decided to focus in this region and to extend the mutation analysis to cases with a negative family history. This study includes 21 mentally retarded male patients selected because they had severe mental retardation and a typical facial appearance. The presence of haemoglobin H or urogenital abnormalities was not considered critical for inclusion in this study. We have identified six mutations which represents a mutation detection rate of 28%. This figure is high enough for us to propose this strategy as a valid first level of screening in a selected subset of males with mental retardation. This approach is simple, does not require RNA preparation, does not involve time consuming mutation detection methods, and can thus be applied to a large number of patients at a low cost in any given laboratory. (+info)
Deletion mapping and X inactivation analysis of a non-specific mental retardation gene at Xp21.3-Xp22.11.
(15/2787)
We report on deletion mapping and X inactivation analysis of a gene for X linked non-specific mental retardation (MRX) at Xp21.3-Xp22.11, on the basis of molecular studies in two families with Xp microdeletions involving the DAX-1 gene. In family A, mental retardation (MR) was profound in the older brother with an episode of adrenal crisis, severe in the younger brother with no episode of adrenal crisis, and mild to moderate in the sister and the mother with no signs of adrenal hypoplasia. In family B, MR was absent in the male patient with adrenal hypoplasia. Polymerase chain reaction for 16 loci in the middle of Xp showed that the brothers of family A had a small Xp deletion between DXS7182 and DXS1022, and that the patient of family B had a tiny Xp deletion between DXS319 and DXS1022. Microsatellite analysis for tetranucleotide repeats in the promoter region of the DAX-1 gene and Southern blotting for DAX-1 and DXS28 showed that the sister and the mother of family A were heterozygous for the interstitial deletion. X inactivation analysis for the methylation status of the AR gene and the HPRT gene indicated that the normal X and the deleted X chromosome underwent random X inactivation in both the sister and the mother. The results imply that an MRX gene subject to X inactivation is present in a roughly 4 Mb region between DXS7182 and DAX-1, and that reduced expression of the normal MRX gene caused by random X inactivation results in MR in carrier females. (+info)
Safety of radiographic imaging during pregnancy.
(16/2787)
Maternal illness during pregnancy is not uncommon and sometimes requires radiographic imaging for proper diagnosis and treatment. The patient and her physician may be concerned about potential harm to the fetus from radiation exposure. In reality, however, the risks to the developing fetus are quite small. The accepted cumulative dose of ionizing radiation during pregnancy is 5 rad, and no single diagnostic study exceeds this maximum. For example, the amount of exposure to the fetus from a two-view chest x-ray of the mother is only 0.00007 rad. The most sensitive time period for central nervous system teratogenesis is between 10 and 17 weeks of gestation. Nonurgent radiologic testing should be avoided during this time. Rare consequences of prenatal radiation exposure include a slight increase in the incidence of childhood leukemia and, possibly, a very small change in the frequency of genetic mutations. Such exposure is not an indication for pregnancy termination. Appropriate counseling of patients before radiologic studies are performed is critical. (+info)