Functional communication as a predictor of depression and anxiety symptoms among adolescents seeking bariatric surgery.

The purpose of the present study was to determine whether functional communication and parent-adolescent relations prospectively predict anxiety and depression symptoms among severely obese adolescents seeking bariatric surgery. Participants included 30 adolescents and their primary caregivers, who presented for enrolment in a study assessing the safety and efficacy of the laparoscopic adjustable gastric band. Adolescents and their caregivers completed questionnaires assessing anxiety and depression symptoms, functional communication, and parent-adolescent relations at baseline and immediately prior to having bariatric surgery. Regression analyses revealed that poorer parent reported functional communication at baseline predicted increases in adolescent reported anxiety and depression symptoms immediately prior to surgery (on average 8.8 months later), above and beyond baseline symptoms. Anxiety and depression symptoms did not predict functional communication over time. Parent-adolescent relations, as reported by the adolescent, were concurrently associated with adolescent reported depression symptoms at baseline, and were concurrently associated with adolescent reported anxiety and depression symptoms, as well as parent reported depression symptoms, immediately prior to surgery. Functional communication may be an important prospective risk factor for the development of anxiety and depression symptoms among severely obese adolescents seeking bariatric surgery, whereas adolescent report of the parent-adolescent relationship appears to be concurrently related to anxiety and depression symptoms. Future research should examine whether specifically targeting communication skills and family relationships within psychological treatment would improve psychosocial functioning among severely obese adolescents.

Mapping of a further malignant hyperthermia susceptibility locus to chromosome 3q13.1.

Malignant hyperthermia (MH) is a potentially lethal pharmacogenetic disease for which MH susceptibility (MHS) is transmitted as an autosomal dominant trait. A potentially life-threatening MH crisis is triggered by exposure to commonly used inhalational anesthetics and depolarizing muscle relaxants. The first malignant hyperthermia susceptibility locus (MHS1) was identified on human chromosome 19q13.1, and evidence has been obtained that defects in the gene for the calcium-release channel of skeletal muscle sarcoplasmic reticulum (ryanodine receptor; RYR1) can cause some forms of MH. However, MH has been shown to be genetically heterogeneous, and additional loci on chromosomes 17q and 7q have been suggested. In a collaborative search of the human genome with polymorphic microsatellite markers, we now found linkage of the MHS phenotype, as assessed by the European in vitro contracture test protocol, to markers defining a 1-cM interval on chromosome 3q13.1. A maximum multipoint lod score of 3.22 was obtained in a single German pedigree with classical MH, and none of the other pedigrees investigated in this study showed linkage to this region. Linkage to both MHS1/RYR1 and putative loci on chromosome 17q and 7q were excluded. This study supports the view that considerable genetic heterogeneity exists in MH.

Multiple interacting gene products may influence susceptibility to malignant hyperthermia.

Malignant hyperthermia (MH) is a potentially lethal disorder triggered in susceptible individuals on exposure to common anaesthetic agents. Crises reflect the consequences of disturbed skeletal muscle calcium homeostasis. MH is an autosomal dominant, genetically heterogeneous trait. Defects in a single major gene have been assumed to determine susceptibility status in individual families. However, in some pedigrees phenotypic and genotypic data are discordant. One explanation, in contrast to the current genetic model, is that susceptibility is dependent upon the effects of more than one gene. Using the transmission disequilibrium test we assessed the involvement of 8 MH candidate loci (RYR1, CACNA1S, CACNA2D1, MHS4 at 3q13.1, MHS6 at 5p, LIPE, DM1, dystrophin) by analysis of data from 130 MH nuclear families. Results suggested that variations in more than one gene may influence MH susceptibility in single families.

The G1021A substitution in the RYR1 gene does not cosegregate with malignant hyperthermia susceptibility in a British pedigree.

A single base change in the RYR1 gene encoding the skeletal muscle ryanodine receptor (calcium-sensitive calcium-release channel of the sarcoplasmic reticulum), resulting in the substitution of G1021 by A, has been proposed to underlie malignant-hyperthermia (MH) susceptibility in as many as 10% of cases in the European population. As part of our mutation-screening program in MH-susceptible (MHS) individuals, we have investigated this substitution in individuals from 151 unrelated British MHS families and have detected G1021A heterozygotes in 7 families. This mutation was not found in 156 unrelated MH-negative (MHN) individuals. We also examined eight families with central core disease (CCD): the mutation did not occur in any family members of any disease status (affected or unaffected for CCD, MHS, or MHN). In one large family, the G1021A mutation was found but did not show complete cosegregation with MH susceptibility: it occurred in only 7/12 MHS individuals in the kinship, and susceptibility was inherited from parents who were G1021 homozygotes, as well as from parents who were heterozygotes. On the basis of these findings, it is clearly unreliable at present to offer presymptomatic DNA testing for MH status, even in families in which a mutation has been detected.

Genetic heterogeneity and HOMOG analysis in British malignant hyperthermia families.

Malignant hyperthermia (MH) is an autosomal dominant genetic condition that presents in susceptible people undergoing general anaesthesia. The clinical disorder is a major cause of anaesthetic morbidity and mortality. The UK Malignant Hyperthermia Group has performed genetic linkage analysis on 20 large, well defined malignant hyperthermia families, using hypervariable markers on chromosome 19q13.1, including the candidate MH gene RYR1, the gene coding for the skeletal muscle ryanodine receptor protein. The results were analysed using LINKAGE to perform two point and multipoint lod scores, then HOMOG to calculate levels of heterogeneity. The results clearly showed genetic heterogeneity between MH families; nine of the families gave results entirely consistent with linkage to the region around RYR1 while the same region was clearly excluded in three families. In the remaining eight MHS families there were single recombinant events between RYR1 and MH susceptibility. HOMOG analysis was of little added benefit in determining the likelihood of linkage to RYR1 in these families. This confirmation of the presence of heterogeneity in the UK MH population, along with the possibility of the presence of two MH genes in some pedigrees, indicates that it would be premature and potentially dangerous to offer diagnosis of MH by DNA based methods at this time.

Segregation of malignant hyperthermia, central core disease and chromosome 19 markers.

Malignant hyperthermia (MH) is an autosomal dominant disorder presenting under general anaesthesia. It is occasionally associated with a myopathy, central core disease (CCD), named after its predominant histochemical characteristic. The penetration of CCD is variable, but typically affected individuals show delayed motor milestones in infancy and remain physically compromised. It was thought until recently that individuals with CCD were always susceptible to MH. Individuals from eight CCD families were screened for the presence of 13 mutations in the skeletal muscle ryanodine receptor gene, reported previously to be associated with MH and/or CCD: none was detected. In seven of these families, where CCD and MH co-existed, we examined the segregation of CCD, MH susceptibility and chromosome 19q markers. In four families, there was complete co-segregation between MH, CCD and the chromosome 19 markers, but in one large pedigree there was a clear lack of segregation of CCD with either MH or chromosome 19 markers and there was no segregation between MH and these markers. This is unequivocal evidence that CCD, in common with MH, is genetically heterogeneous. In the two other families, CCD segregated with chromosome 19 markers but not all individuals with CCD were susceptible to MH. We recommend determination of MH susceptibility in all patients with CCD, irrespective of the MH status of their relatives with CCD.

A genome wide search for susceptibility loci in three European malignant hyperthermia pedigrees.

Malignant hyperthermia (MH) is an autosomal dominant disorder which is potentially lethal in susceptible individuals on exposure to commonly used inhalational anaesthetics and depolarising muscle relaxants. Crises reflect the consequences of disturbed skeletal muscle calcium homeostasis. Susceptibility was first localised to chromosome 19q13.1 and the skeletal muscle ryanodine receptor, RYR1 (the calcium release channel of the sarcoplasmic reticulum). Defects in this gene have been identified which cosegregate with the MHS phenotype and evidence as to their potential causal roles has accumulated. MH has, however, been shown to be genetically heterogeneous, additional loci on chromosomes 3q, 17q and 7q being proposed. Pedigrees remain in Europe where linkage status is still unclear. In a collaborative search of the human genome conducted with three pedigrees whose disease status was classified according to the European IVCT protocol we have evidence to suggest that at least two further loci exist for MH susceptibility. One of these locates to chromosome 1q, the site of a candidate gene, CACNL1A3, encoding the alpha-subunit of the dihydropyridine receptor. The second region resides on chromosome 5p to where no known candidate has been mapped to date. The third family exhibited inconclusive results which suggests the existence of at least one other locus. This study adds to the evidence for considerable genetic heterogeneity in MH and will provide a route to further our understanding of the molecular pathology of the condition.

Genetic mapping of the beta 1- and gamma-subunits of the human skeletal muscle L-type voltage-dependent calcium channel on chromosome 17q and exclusion as candidate genes for malignant hyperthermia susceptibility.

Malignant hyperthermia susceptibility (MHS) is an autosomal dominant disorder of skeletal muscle which manifests as a life-threatening hypermetabolic crisis triggered by commonly-used inhalation anaesthetics and depolarizing muscle relaxants. Defects in the ryanodine receptor (RYR1) protein have been proposed to underly MHS, but significant genetic heterogeneity in MHS has recently been demonstrated. In order to investigate the potential roles played by other skeletal muscle calcium channels in MHS, we isolated cosmids containing the gene encoding the beta 1-subunit of skeletal muscle L-type voltage-dependent calcium channel (CACNLB1). We identified a new, highly polymorphic dinucleotide repeat motif close to this gene, and linkage analysis placed the marker proximal to the HOX2B locus, previously localized to chromosome segment 17q21-q22. We recently identified a novel marker within the gamma-subunit locus (CACNLG) at band 17q24, and since both markers are within the 17q11.2-q24 region reported to contain the MHS2 locus, we tested them for linkage in MHS families whose disease trait has been shown not to co-segregate with markers for the RYR1 region on chromosome 19q13.1. Our results exclude CACNLB1 and CACNLG as candidate genes for MHS2, and do not support the reported chromosome 17q localization for the MHS2 locus in our families.