Statistical approaches for the detection of heterozygotes for biotinidase deficiency

We applied and evaluated 3 statistical approaches for the detection of heterozygotes for biotinidase deficiency in a randomly selected population of French adults. The first method, which used a cutoff value to dichotomize the population, lacked sensitivity. The second approach calculated the probability of heterozygosity for a given enzyme activity through the application of Bayes theorem to the normal density functions of the enzyme distributions of the obligate heterozygote and the test populations. A priori values of the means and standard deviations (SDs) of the genotypic distributions were used. This method was sufficiently sensitive for both population screening and genetic counseling, but requires prior knowledge of the frequency of the deficient gene (q). The third approach was similar to the second, however, maximum likelihood estimates of the means and SDs of the genotypic distributions were calculated and used to determine the probability of heterozygosity for a given enzyme activity. This method was as sensitive as the second method and is appropriate for screening populations for which there is little prior information about the gene frequency and the genotypic distributions. This method can also be used to estimate the gene frequency of the disorder within a given ethnic or racial population. Using this method, we estimated the frequency of heterozygotes (2pq) in the French population to be 0.012, which was similar to that estimated from the results of neonatal screening for biotinidase deficiency. These methods can be used to detect heterozygotes and to estimate the gene frequency of other inherited enzyme deficiencies.     

A genome-wide search for loci contributing to smoking and alcoholism

Using the Collaborative Study on the Genetics of Alcoholism (COGA) data, we performed a sib-pair linkage analysis of two smoking-related traits and one alcoholism phenotype. The first trait, EVRNVR, was a dichotomous one we constructed based on epidemiological definitions of smoking. The second trait, PKYRS, used the quantitative pack-year history provided, and the third trait was the COGA alcoholism classification, ALDX1. There was some evidence for linkage of the EVRNVR trait to regions-on chromosomes 6, 9, and 14. Smaller numbers of loci provided nominal evidence for linkage to PKYRS, although some candidate gene regions were identified. The number of loci identified using EVRNVR suggests that a threshold-based phenotype may better identify loci affecting smoking history. Approximately one-third of the loci that showed evidence for linkage to EVRNVR at a nominal significance level (p < 0.01) also showed evidence for linkage to ALDX1. Some of these regions may represent loci increasing vulnerability to both smoking and alcoholism.     

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Gene Mapping in the Idiopathic Generalized Epilepsies: Juvenile Myoclonic Epilepsy, Childhood Absence Epilepsy, Epilepsy with Grand Mai Seizures, and Early Childhood Myoclonic Epilepsy

Summary: Idiopathic generalized epilepsies, i.e., juvenile myoclonic epilepsy (JME), childhood absence epilepsy, and epilepsy with grand mal [generalized tonic-clonic seizures (GTCS)], are the most common genetic epilepsies. Linkage studies using Bf, HLA serologic, and DNA markers by three independent investigators, one from Los Angeles and two from Berlin, have localized the JME locus to the short arm of chromosome 6 (6p). Because members of the same JME family have the same JME phenotype of childhood absence epilepsy, epilepsy with grand mal (GTCS) seizures, or early childhood myoclonic epilepsy (ECME), our observations give evidence for a single-locus etiology in 6p for JME and for at least some of the childhood absence seizures, epilepsy with grand mal (GTCS) seizures, and ECME. Studies should now address whether locus heterogeneity exists within childhood absence epilepsy, epilepsy with grand mal (GTCS) seizures, or ECME. Markers linked to JME (Bf, HLA serologic, and DNA markers in the DQ region) can be used to resolve etiologic heterogeneity. Using such markers, both linked and unlinked forms of phenotypes that are clinically indistinguishable may be detected and provide evidence for etiologic heterogeneity. Studies should also concentrate on narrowing the JME locus to 2 to 3 cm by screening families with recombinant events using RFLPs, candidate genes, and new expressed sequences on chromosome 6.     

Biotinidase deficiency: Initial clinical features and rapid diagnosis

Biotinidase deficiency is the primary defect in most individuals with late-onset multiple carboxylase deficiency. We have reviewed the presenting clinical features of 31 children with the disorder. Seizures, either alone or with other neurological or cutaneous findings, are the most frequent initial symptom observed. Other neurological symptoms, such as hypotonia, ataxia, hearing loss, optic atrophy, and developmental delay, are seen, in addition to skin rash and alopecia. The disorder is also characterized by ketolactic acidosis and organic aciduria. Biotinidase activity may be diagnosed using a simple, rapid, semiquantitative colorimetric procedure. Samples of whole blood spotted on the same filter paper used by most states to screen for phenylketonuria and other inborn errors of metabolism may be sent to an appropriate reference laboratory. None of the common anticonvulsants or sedatives used to treat newborns and children interfere with the test. Because biotinidase deficiency can be treated readily with biotin, this disorder should be considered in children with infantile seizures, especially in the presence of other characteristic neurological or cutaneous features.     

Mindfulness meditation alleviates depressive symptoms in women with fibromyalgia: results of a randomized clinical trial

OBJECTIVE: Depressive symptoms are common among patients with fibromyalgia, and behavioral intervention has been recommended as a major treatment component for this illness. The objective of this study was to test the effects of the Mindfulness-Based Stress Reduction (MBSR) intervention on depressive symptoms in patients with fibromyalgia. METHODS: This randomized controlled trial examined effects of the 8-week MBSR intervention on depressive symptoms in 91 women with fibromyalgia who were randomly assigned to treatment (n = 51) or a waiting-list control group (n = 40). Eligible patients were at least 18 years old, willing to participate in a weekly group, and able to provide physician verification of a fibromyalgia diagnosis. Of 166 eligible participants who responded to local television news publicizing, 49 did not appear for a scheduled intake, 24 enrolled but did not provide baseline data, and 2 were excluded due to severe mental illness, leaving 91 participants. The sample averaged 48 years of age and had 14.7 years of education. The typical participant was white, married, and employed. Patients randomly assigned to treatment received MBSR. Eight weekly 2.5-hour sessions were led by a licensed clinical psychologist with mindfulness training. Somatic and cognitive symptoms of depression were assessed using the Beck Depression Inventory administered at baseline, immediately postprogram, and at followup 2 months after the conclusion of the intervention. RESULTS: Change in depressive symptoms was assessed using slopes analyses of intervention effects over time. Depressive symptoms improved significantly in treatment versus control participants over the 3 assessments. CONCLUSION: This meditation-based intervention alleviated depressive symptoms among patients with fibromyalgia.