Relationship between prophylactic effect of lithium therapy and family history of affective disorders.

Lithium therapy response and age of onset (AOO) were studied in 98 patients with bipolar affective disorder (BPAD) who were divided into subgroups depending on type of family history of affective disorders. The highest (33.0 years) and lowest (25.5 years) age of onset were found in nonfamilial patients and in familial patients with a first-degree relative of BPAD, respectively. Nonfamilial patients showed the best response to lithium. There were 0.9 episodes/year off lithium compared to 0.3 episodes/year on lithium (an 88% decrease). A poorer response (a 71% decrease; a reduction from 1.39 episodes per year off lithium to 0.65 on lithium) was found in familial patients with a first-degree relative of BPAD. Differences in serum lithium values between the groups could not explain the observed differences. Thus, familial patients showed a more severe manifestation of the disease with an earlier AOO and a lower prophylactic effect of lithium.

Expanded trinucleotide CAG repeats in families with bipolar affective disorder.

Clinical anticipation has been reported in bipolar affective disorder (BPAD). The hypothesis that expanded trinucleotide repeats are related to anticipation and transmission pattern in families with bipolar affective disorder is tested in this study. Eighty-seven two-generation pairs of patients recruited from 29 bipolar families were analyzed. The repeat expansion detection method was used to detect CAG repeat expansions between successive generations. Significant changes in age at onset and episode frequency in successive generations were observed. Mean trinucleotide CAG repeat length between parental and offspring generation significantly increased when the phenotype increased in severity, i.e., changed from major depression, single episode or unipolar recurrent depression to BPAD. A parent-of-origin effect was also observed with a significant increase in median length CAG between G1 and G2 with maternal inheritance. This increase was observed notably in female offspring. Our findings indicate for the first time that expansion of CAG repeat length could explain the clinical observation of anticipation in families with BPAD. These results provide further support for expanded trinucleotide repeat sequences as risk factors in major affective disorders.

Identification of a susceptibility locus for migraine with and without aura on 6p12.2-p21.1.

Migraine is the most common type of chronic episodic headache. To find novel susceptibility genes for familial migraine with and without aura, a genomewide screen was performed in a large family from northern Sweden. Evidence of linkage was obtained on chromosome 6p12.2-p21.1, with a maximum two-point lod score of 5.41 for marker D6S452. The patients with migraine shared a common haplotype of 10 Mb between markers D6S1650 and D6S1960.

Linkage analysis of a large Swedish kindred provides further support for a susceptibility locus for schizophrenia on chromosome 6p23.

Several reports have indicated genetic linkage between markers on the short arm of chromosome 6 and schizophrenia. However, significant threshold levels were not always achieved, and the chromosomal regions identified are large and different in different families. One way to decrease the problem of heterogeneity is to study a single extended pedigree. Here we report the analysis of a very large, previously undescribed pedigree from northern Sweden that includes 31 affected individuals. We typed 16 markers spanning 40 cM on the short arm of chromosome 6. Linkage analysis was performed only with the affected individuals. Suggestive lod scores (maximum 2.6) were obtained with markers on chromosome 6p23 in a single branch of the large pedigree indicating possible heterogeneity inside the family. A haplotype comprising markers from D6S309 to D6S1578 was found to segregate with the disease. This chromosomal region is included within a segment proposed to contain a susceptibility gene for schizophrenia by many other investigators. Our results thus give further support for a possible localization of a susceptibility locus for schizophrenia in 6p23 and help to narrow the candidate chromosomal region to the segment included between markers D6S309 and D6S1578.

Tyrosine hydroxylase polymorphism and phenotypic heterogeneity in bipolar affective disorder: a multicenter association study.

Tyrosine hydroxylase (TH), the rate-limiting enzyme in the metabolism of catecholamines, is considered a candidate gene in bipolar affective disorder (BPAD) and has been the subject of numerous linkage and association studies. Taken together, most results do not support a major gene effect for the TH gene in BPAD. Genetic and phenotypic heterogeneity may partially explain the difficulty of confirming the exact role of this gene using both association and linkage methods. Four hundred one BPAD patients and 401 unrelated matched controls were recruited within a European collaborative project (BIOMED1 project in the area of brain research, European Community grant number CT 92-1217, project leader: J. Mendlewicz) involving 14 centers for a case-control association study with a tetranucleotide polymorphism in the TH gene. Patients and controls were carefully matched for geographical origin. Phenotypic heterogeneity was considered and subgroup analyses were performed with relevant variables: age at onset, family history, and diagnostic stability. No association was observed in the total sample or for subgroups according to age at onset (n = 172), family history alone (n = 159), or high degree of diagnostic stability and a positive family history (n = 131). The results of this association study do not confirm the possible implication of TH polymorphism in the susceptibility to BPAD.

Anticipation in Swedish families with schizophrenia.

Nineteen parent-offspring pairs obtained from 14 two-generation families with available medical records and diagnosis of schizophrenia were studied to compare the ages of onset of the parent generation with those of the offspring generation. The mean age of onset for the parent generation was 37.3 +/- 6.0 years and for the offspring generation was 20.8 +/- 4.4. The mean difference was thus 16.5 +/- 6.2, suggesting the occurrence of anticipation in schizophrenia (p < 0.001). Although some ascertainment biases (like reduced fertility in early-onset parents or early detection of symptoms in offsprings of affected parents) may partially contribute to the occurrence of anticipation, this study replicates recent reports of anticipation in several neuropsychiatric disorders, some of which have been shown to be associated with unstable expansions of trinucleotide repeats in the genomic DNA.

Migraine: temperament and character.

The personality profile of 26 adult migraine patients from a large Swedish family with migraine and 87 controls were studied by means of Cloninger's seven-factor model of Temperament and Character (TCI; Temperament and Character Inventory). For the diagnosis of migraine, a questionnaire, slightly modified to fit the criteria according to the AD HOC committee on the classification of headaches of the International Headache Society, was used. The TCI assesses four dimensions of temperament, including novelty-seeking (NS), harm avoidance (HA), reward dependence (RD) and persistence (P), and three dimensions of character, including self-directedness (SD), co-operativeness (C) and self-transcendence (ST). Psychiatric morbidity did not differ between this family and the general population. One migraine patient had double depression (dysthymia and recurrent depression) and one had a personality disorder. No significant difference could be found in the higher order dimensions of temperament (NS, HA, RD and P) and character (SD, C and ST) between migraine patients and controls. However, on the subscale level, NS showed a slightly higher average in NS1 (exploratory excitability) and a significantly higher (p = 0.0448) average in NS2 (impulsivity) in migraine patients compared to controls. Somatic anxiety has been shown to be positively correlated with NS, and especially impulsivity. Our results showed a tendency of this personality profile, and may suggest an association between migraine and somatic anxiety.

Anticipation in unipolar affective disorder.

Anticipation describes an inheritance pattern within a pedigree with an increase in disease severity and/or decrease in age at onset in successive generations. The phenomenon of anticipation has recently been shown to be correlated with the expansion of trinucleotide repeat sequences in a neuromuscular disease, various neurodegenerative disorders and mental retardation. We have studied parent-offspring differences in age at onset and disease severity in 31 pairs with unilineal inheritance of unipolar affective disorder (UPAD). Life-table analyses showed a significant decrease in survival to 1st episode of major depression in the offspring generation compared with the parental generation (P = 0.0007). There was also a significant difference in age at onset (P < 0.001) between parents and offsprings. The offspring generation experienced onset 15.6 years earlier and illness 1.5 x more severe than did the parent generation. Furthermore, there was a significant correlation (P < 0.05) in age at onset between parent and offspring generations. When we excluded pairs where the affected parent has an age of onset greater than the age of the child at the time of ascertainment (i.e., 23 pairs left), there was still a significant (P = 0.02) decrease in age at onset (8.4 years) and 1.5 x more severe disease in the offspring generation. No evidence for specific maternal or paternal inheritance was found. We found evidence of anticipation in 75-80% of this sample of unilineal family pairs of UPAD. Anticipation is, thus, an inheritance pattern in a large group of UPAD which suggests that the expansion of trinucleotide repeat sequences is a possible mode of inheritance in this group of UPAD. The findings of anticipation in this study of families with UPAD and previous findings in families with BPAD suggest that the variable expression of unstable expansions of trinucleotide repeats may turn out to be the basis of the continuum of liability in affective disorders.

Mutagenic effects of petrol in Drosophila melanogaster I. Effects of benzene and 1,2-dichloroethane.

Commercial petrol and two of its components, benzene and 1,2-dichloroethane, were tested for mutagenicity in Drosophila melanogaster. The chemicals were given to larvae through their food supply. A genetically unstable sexlinked test system caused by a transposable genetic element was used. Mutagenicity was measured by the frequency of somatic mutations for eye pigmentation. Commercial petrol and 1,2-dichloroethane showed mutagenic activity. With the system used, benzene did not show any mutagenic activity. The high frequency of mutations induced by 1,2-dichloroethane indicate the existence in Drosophila of a metabolic activating system.

Temperament and character in women with postpartum depression.

OBJECTIVE: To investigate whether women with postpartum depression differ in personality traits from healthy postpartum women, healthy controls from the normal Swedish population and non-postpartum women with major depression. METHODS: Forty-five women with postpartum depression were compared with 62 healthy postpartum women, 62 age-matched, healthy, non-postpartum women from a normal sample and 74 non-postpartum women with major depression from a clinical sample. The edinburgh postnatal depression scale was used in order to screen for postpartum depression. A clinical diagnostic interview was done including a rating with the Montgomery-Asberg depression rating scale. Personality i.e. temperament and character was measured by the temperament and character inventory. RESULTS: Harm avoidance (HA) was higher (p < 0.001) and self-directedness (SD) scored lower (p < 0.001) in women with postpartum depression compared to healthy postpartum women. These differences were the most important differences between these two groups. Women with postpartum depression scored lower (p = 0.001) in cooperativeness (CO) and higher (p = 0.019) in self-transcendence (ST) compared to healthy postpartum women. Women with postpartum depression scored overall similar to women with major depression. CONCLUSION: High HA and low SD can be seen as vulnerability factors for developing a depression and especially in a stressful situation as childbirth.

Transferrin C subtypes and ethnic heterogeneity in Sweden.

Transferrin (TF) C subtypes were studied in Swedish Lapps (Saami) and in Swedes from northern, central and southern Sweden, and the allele frequencies were compared with those in other European populations. The Swedish Lapps were found to have the lowest frequency of the TF*C3 allele (1-2%) so far observed in Europe. Most European populations have TF*C3 allele frequencies between 5 and 7%. Finns differ by having high TF*C3 frequencies (13-14%). The relatively high TF*C3 frequencies found in northeastern Sweden (13%) and in central Sweden (9%) are most likely due to eastern influence. Unlike other genetic markers of eastern influence (e.g. TF*DCHI), which are of Asiatic Mongoloid origin, TF*C3 appears to originate from Finno-Ugric populations.

Population studies in northern Sweden. XVII. Estimates of Finnish and Saamish influence.

The North-Swedish population is a mixture of Finnish, Saamish and Central-Swedish ethnic groups. We have studied the Finnish and Saamish admixture by means of genetic markers in 23 North-Swedish subpopulations. The Finnish influence was estimated using the transferrin genes B0-1, DCHI and C3 and the enzyme gene SOD1*2, and markers for Saamish influence were the blood group gene ABO*A2, the serum group gene GC*1F and the enzyme gene 6PGD*C. In the subpopulations the Finnish influence (admixture) varied between 0 and 84% and the Saamish influence between 0 and 34%. The Saamish influence was strongest in the western and northern parts of the area. In the northern part of the area, between 1/4 and 1/3 of the gene pool of the present-day population may be Saamish in origin. The Finnish influence was strongest in the northern and northeastern parts of the area. In the subpopulations along the Finnish border, between 60 and 80% of the gene pool may be Finnish in origin. Significant correlations were found between the Saamish marker genes and between the Finnish marker genes. Due to geographical overlapping of Finnish and Saamish influence, significant correlations were also found between Finnish and Saamish marker genes. The geographical pictures of Saamish and Finnish influence in northern Sweden showed a fair agreement with the expectations derived from historical knowledge. Although a substantial part of the genetic heterogeneity of the North-Swedish population is ethnic in origin, it is obvious that founder effect and genetic drift also have played an important role.

Population studies in northern Sweden. XVI. GC subtypes.

The frequencies of group-specific component (GC) subtypes were studied in a population of 4,053 conscripts and blood donors from the counties of Västerbotten and Norrbotten in northern Sweden. The individuals were distributed according to place of birth into 23 subpopulations. A significant heterogeneity between the 23 regions was observed for the GC*1F, GC*1S and GC*2 genes, and clines were found for all genes. The frequency of the GC*1F gene was increasing in the northern direction, and the frequencies of the GS*1S and GC*2 genes were increasing in the southern direction. The geographical pattern of the GC*1F gene frequency could be explained in terms of Lappish influence.

Population studies in northern Sweden. XV. Transferrin C subtypes.

The frequencies of transferrin C (TF C) subtypes were studied in 315 Finns, 222 Swedish Lapps and in 4,157 conscripts and blood donors from the counties of Norrbotten and Västerbotten in northern Sweden. The Swedish individuals were distributed according to place of birth into 23 subpopulations or regions. A significant heterogeneity between the 23 regions was observed for the TF C1, C2 and C3 genes and for rare genes. Clines were found for the TF C1 and C3 genes and for rare transferrin genes in northern Sweden. The frequencies of the C1 and C3 genes were increasing in the southwestern and northeastern direction, respectively, and the frequency of the rare transferrin genes was increasing in the northern direction. The geographical picture of the C3 gene and of rare transferrin genes could be interpreted in terms of Finnish influence. The frequency of the TF C3 gene in Finland and northern Sweden (14 and 15%) is the highest so far reported in the world. The overall picture of geographical variations of the C1 and C2 genes were not explainable in terms of ethnic influence and may be caused by random differentiation and/or selective forces.

Gc subtypes in Finns, Swedes and Swedish Lapps.

The group-specific component (Gc) subtypes were determined by isoelectric focusing and immunoblotting. The gene frequencies in the Swedish Lapps were Gc1F = 0.412, Gc1S = 0.367 and Gc2 = 0.221, which was significantly different from the frequencies found in Finns and in the populations of northern and central Sweden (p less than 0.001). The gene frequencies in the Swedish Lapps, although similar to those in Asiatic populations, are probably not reflecting an Asiatic influence, since the accumulated genetic information on the Swedish Lapps suggests that founder effect and genetic drift are to a large extent responsible for the peculiar gene pool of the original Lapp population.

Polycystic lipomembranous osteodysplasia with sclerosing leukoencephalopathy (PLO-SL): a genealogical study of Swedish families of probable Finnish background.

Four Swedish families in northern Sweden with polycystic lipomembranous osteodysplasia (PLO-SL) were studied genealogically. Historical and genealogical date provided evidence for a Finnish origin. Both parents of two of the families could be traced back to Finnish ancestors, and the other two families had a common origin in a region with a known Finnish influence, but without evidence for Finnish ancestry. PLO-SL is the first rare monogenic disease with an autosomal recessive inheritance in Sweden with a probable Finnish origin.

Association of C3 and C4A complement types with familial amyloidotic polyneuropathy.

A mutant variant of the serum protein transthyretin (TTR-met30) appears to be a necessary but not sufficient condition for the development of familial amyloidotic polyneuropathy (FAP). We have studied a number of serum protein markers (alpha 1-antitrypsin, properdin factor B, C3, C4A, C4B, haptoglobin, transferrin and group-specific component) in FAP patients and healthy controls in an attempt to identify additional pathogenic factors which may influence the risk for developing FAP in male and female patients as well as the age of onset of the disease. Statistically significant associations were found in the complement systems C3 and C4A. The C3F variant was significantly increased in all FAP patients with a relative risk (RR) of 2.0, more pronounced in female patients (RR = 2.6) and patients with an early onset of the disease (RR = 4.5). In the FAP patients only the variants A3 and A4 were found in the C4A system. C4A3 was found in all patients, which was significantly higher than in the controls. The remaining serum protein systems showed no statistically significant associations with FAP. The results suggest that genetic variants of complement factors C3 and C4A may interact with the mutant TTR-met30 by modifying the expression and onset of FAP.

Population studies in northern Sweden. XIV. Variation of the A1A2B0 blood group gene frequencies.

Frequencies of the A1A2B0 blood group genes were studied in a material of 5,632 conscripts and blood donors from the counties of Norrbotten and Västerbotten in northern Sweden. The individuals were distributed according to place of birth into 23 subpopulations. In northern Sweden different clines were found for the A1, A2 and 0 genes. The frequencies of the A1 and A2 genes were increasing in the northeastern respectively northern direction, and the frequency of the 0 gene was increasing in the southwestern direction. These geographical patterns could be explained in terms of Finnish and Lappish influence.