Search PubMed⌕ Search

Biomedical subjects

A W Eriksson

Publications and source records attributed to A W Eriksson.

At least 37 records · Page 2Linked to original sources
PubMed1992

Twinning and the r/K reproductive strategy: a critique of Rushton's theory.

The theory of r selection, favoring population growth, as opposed to K selection, favoring more efficient utilization of resources, has in recent years been applied by Rushton to contrast human ethnic groups in terms of their r/K reproductive strategies, suggesting the existence of a continuum from r groups, producing many offspring but providing little parental care, to K groups, producing few offspring but providing much parental care. Rushton's theory, which is largely based on ethnic differences in twinning rates, is here critically examined. It is pointed out that twinning rate differences are not necessarily genetic in origin since various environmental factors clearly play a role, and also that twinning, as a mode of reproduction, is not necessarily an r strategy, considering the high prenatal and perinatal selection to which it has been, and still is, associated. Moreover, Rushton misinterprets a number of relevant aspects related to the biology of twinning. The claim that ethnic differences in twinning rates provide evidence for an r/K typology in human populations with respect to reproductive strategies does not appear to be warranted.

Animals↗
PubMed1992

Wolman disease: morphological, clinical and genetic studies on the first Scandinavian cases.

On the Aland Islands, a 1-month-old girl was diagnosed as having Wolman disease. The diagnosis was confirmed neurochemically; a decreased activity of acid lipase was noted in the proband and her parents had typical carrier values. This is the first Scandinavian case reported. The skin biopsy revealed cytoplasmic accumulations identical to those noted in two sibs who highly probably had Wolman disease during the 1950s. Both these sibs died at the age of about 3 months and presented a heavy accumulation of lipid material in lymph nodes, spleen, adrenal glands, liver, gut, and also some pathological alterations in other organs. Electron microscopic findings from deparaffinized samples showed cytoplasmic accumulation of lipid material similar to that noted in Wolman disease. Genealogical analyses revealed that the index families had ancestors from the same restricted area and also common ancestors during the 17th century. The parents of the two affected sibs were born on a small island and were related in many different ways. On the basis of genealogical studies and other genetic investigations performed, the importance of founder and drift effect for manifestations of rare hereditary disorder in isolates is stressed.

Consanguinity↗
PubMed1992

Juvenile cataract with autosomal recessive inheritance. A study from the Aland Islands, Finland.

Juvenile (including congenital and infantile) cataract occurs commonly as part of a more generalized or systematic condition, or as a component of a syndrome. Isolated juvenile cataract is a relatively rare disorder and the mode of inheritance is often autosomal dominant. Autosomal recessive transmission of isolated juvenile cataract is rare. The present paper is a report of 15 cases of juvenile cataract on the Aland Islands (Finland) with about 23,000 inhabitants. Twelve belong to 7 sibships of two different pedigrees and 3 cases are sporadic, of which we have found no genealogical connections in the last 6-10 generations to the two cataracta pedigrees. One of the sporadic cases presented an operated cleft palate and a chromosomal anomaly. In another sporadic case the mother probably had been infected with rubella during early gestation. In the third sporadic case the cataract was combined with partial aniridia, but he has several genealogical connections to one of the cataract pedigrees. Consanguinity between the parents was detected in 5 of the 7 sibships, in some even on various ancestral levels. Apart from the cataracts, all patients were healthy, with normal intellect, behavior, hearing, growth and development. They were neurologically intact and there were no ocular lesions apart from cataract. In the Alandic familial cases the cataracts appear to be an autosomal recessive trait. A family branch originating from southwestern Sweden and south Norway showed transmission of the cataract in three successive generations. The possibility of quasi-dominant inheritance is discussed against the background that autosomal recessive juvenile cataract may not be so rare as the small number of recorded cases would suggest.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1991

High-performance liquid chromatography: purification and chromatographic behaviour of molecular variants of pepsinogen A from human urine.

By combining conventional DEAE chromatography with high-performance liquid chromatography on Sephacryl S-200 HR and Mono-Q columns, we have been able to isolate and fractionate human pepsinogen A (PGA) isozymogens from large amounts of urine. This method of fractionation is simple and allows one to obtain pepsinogen in a native non-denatured conformation. The isozymogens are homogeneous by electrophoretic and chromatographic criteria; this was confirmed by N-terminal amino acid sequencing. Purified PGA-3 and PGA-5 can be converted into an additional, more anionic, isoform on incubation at 37 degrees C. This isoform exists not only in vitro but also in vivo. The net negative charge of the PGA isozymogens is in the order PGA-5 less than deamidated PGA-5 less than PGA-3 less than deamidated PGA-3. Surprisingly, the elution order on the Mono-Q column was PGA-5/PGA-3/deamidated PGA-5/deamidated PGA-3. We have performed molecular modelling on PGA to investigate this phenomenon in terms of surface charge (not net charge) of the proteins. The model provides evidence that (1) only a fraction of the protein surface interacts with the support and (2) regions of localized charge at the protein surface may allow portions of the external surface to dominate chromatographic behaviour, resulting in a steering of the proteins with respect to the oppositely charged matrix. Pepsinogens may serve as model proteins for elucidating some of the variables that determine the chromatographic behaviour of proteins on ion-exchange columns.

Chromatography, High Pressure Liquid↗
PubMed1991

Genetic mapping of 12 marker loci in the Xp22.3-p21.2 region.

To provide a more precise genetic map of the p22.3-p21.2 region on the short arm of the human X chromosome, we performed multilocus linkage studies in an expanded database including 31 retinoschisis families and 40 normal families. Twelve loci from this region were examined. Although significant lod scores were observed between various pairs of markers by two-point linkage analysis, the confidence limits were found to be broad. The most likely gene order on the basis of multilocus analysis was Xpter-DXS89-DXS85-DXS16-(DXS207,DXS43++ +)-DXS274-(DXS41, DXS92)-ZFX-DXS164-Xcen. All other alternative orders were excluded by odds of at least 40:1.

Chromosome Mapping↗
PubMed1991

Changes in the DZ unlike/like sex ratio in The Netherlands.

Based on Dutch twin incidence figures since the beginning of the current century, evidence is provided in support of the idea that the DZ unlike/like sexed ratio has gradually shifted (since 1900) from unity to less than unity. Opposing conclusions with regard to the justification of the use of Weingberg's differential rule are very probably correct in themselves but could depend on country and period of birth of the twin sample used. Furthermore, the fast drop and subsequent rise in DZ twinning rate between about 1963 and 1990 can very likely for the greater part be ascribed to a parallel shift in maternal age.

Female↗
PubMed1991

Clinical and electroretinographic comparison between Aland Island eye disease and a newly found related disease with X-chromosomal inheritance.

Two subjects representing AIED (Aland Island Eye Disease) and a family with 5 males affected with an AIED related X-linked hereditary eye disease were studied clinically and electrophysiologically. The clinical picture of AIED includes myopia and astigmatism, reduced visual acuity, nystagmus, ocular albinism, hemeralopia and dyschromatopsia (No. 300600, McKusick 1990). The subjects with the related disease showed astigmatism with or without myopia, reduced visual acuity, slight hemeralopia, normal color vision in 3/5 subjects, no ocular albinism and nystagmus only in one case. In both diseases the ERG was abnormal showing defective a- and b-waves, but there were also differences. The most notable was the greater reduction of the b-wave amplitude in the mixed (rod and cone) responses for the white stimulus in the ERG of the AIED related disease. With regard to the pathogenesis we propose that in both diseases rod and cone functions are defective but in an AIED related disease a defective cone function inhibits the transmission of the rod signals to the rod bipolars, causing greatly reduced mixed responses. The clinical and ERG findings of this study suggest that the 5 subjects of our family do not represent AIED but another X-linked hereditary eye disease. The investigation to find out the gene locus of this disease is going on.

Adolescent↗
PubMed1991

Localization of the Aland Island eye disease locus to the pericentromeric region of the X chromosome by linkage analysis.

Aland Island eye disease (AIED) is an X-chromosomal disorder characterized by reduced visual acuity, progressive axial myopia, regular astigmatism, latent nystagmus, foveal hypoplasia, defective dark adaptation, and fundus hypopigmentation. The syndrome was originally reported in 1964 in a family on the Aland Islands. To determine the localization of the AIED gene, linkage studies were performed in this family. total of 37 polymorphisms, covering loci on the entire X chromosome, were used. By two-point analysis the strongest evidence for linkage was obtained between AIED and DXS255 (maximum lod score [Zmax] 4.92 at maximum recombination fraction [theta max] .00). Marker loci DXS106, DXS159, and DXS1 also showed no recombination with AIED. Other positive lod scores at theta max .00 were obtained with markers localized in the XY homologous region in Xq13-q21, but the numbers of informative meioses were small. Multilocus linkage analysis indicated that the most probable location of AIED is in the pericentromeric region between DXS7 and DXS72. These results rule out localizations of AIED more distal on Xp that have been proposed by others. Our data do not exclude the possibility that AIED and incomplete congenital stationary night blindness are caused by mutations in the same gene. This question should be resolved by careful clinical comparison of the disorders and ultimately by the molecular dissection of the genes themselves.

Albinism, Ocular↗
PubMed1990

Evolution of the human alpha-amylase multigene family through unequal, homologous, and inter- and intrachromosomal crossovers.

Human amylase haplotypes differ from each other by different numbers of a long direct repeat unit of approximately 100 kb, encompassing two complete salivary amylase genes and one amylase pseudogene lacking the first three exons. The two salivary genes are part of a 75-kb-long inverted repeat. Two short sequences, hybridizing with a probe containing exons 1-3, were found in the central part of the inverted repeat. Sequencing showed that these fragments, designated r, contain exon 3 sequences. We present evidence that these r-fragments and the pseudogene most likely are remnants of the same ancestral pancreatic gene. We determined the orientation of the exon 3 sequences present in the r-fragment and show that an inversion can explain their origination. Hybridization studies, using random fragments from the intergenic region of the AMY gene cluster as probes, enabled us to detect more extended homologous regions in this cluster than were found previously on the basis of restriction maps only. Together, these results allow us to present a model for the evolution of the human amylase multigene family by a number of consecutive events involving inter- and intrachromosomal crossovers.

Base Sequence↗
PubMed1990

Twinning in families of triplets.

A study was conducted on twinning in relatives of consecutive triplet sets in the Aland Islands in the years 1740-1939. The incidence of twinning in sibships of triplets was extremely high, 80/1000 (56/1000 before and 143/1000 after the triplet maternity). In Finland as a whole, 1905-1954, the twinning rate was among mothers of triplets 38/1000, ie, about 2.6 times the rate in general population, and was higher after (48/1000) than before the triplet maternity (34/1000). In the sibships of fathers of triplets there was a low rate of twinning (below 10/1000) both of same-sexed (SS) and of opposite-sexed (OS) triplets. Among sibships of mothers of OS triplets the twinning rate was 18/1000 and among mothers' sibships of SS triplets 26/1000. The series of triplet families from both Aland and Finland as a whole indicate a considerably higher frequency of twinning on the maternal than on the paternal side. The sibships of OS triplets in Finland have higher twinning rates than sibships of SS triplets (50/1000 vs 27/1000). In sibships of triplets, not only the DZ but also the MZ twinning rates were approximately twice as high as those in the general population. The triplet rates in Finland were increasingly strong with maternal age and were in the last century among mothers of 30-39 years of age considerably higher than among mothers from this century. This, in combination with higher mean parity, may explain the high rates of multiple maternities in sibships of triplets in the past. The rate of triplet maternities seems to be more sensitive to sociodemographic changes than the rate of twin maternities. Mothers of triplets in Finland had a high frequency (more than 40%) of prenuptially conceived firstborn children. This, and a short protogenesic interval indicate that triplet-prone mothers are more fecundable, ie, they conceive with greater ease and/or may have a better physical condition than other women for completing a gestation with multiple embryos.

Adult↗
PubMed1990

A mathematical model for recurrent twinning.

In an attempt to improve our understanding of the factors that affect human twinning, we further developed the models given by Hellin (1895) and Peller (1946). The connection between these models and our own model ("Fellman's law") were studied. These attempts have resulted in a more general model, which was then applied to data from Aland Islands (1750-1939), Nmes (1790-1875), Stuttgart (about 1790-1900) and Utah (1850-1900). The product of the mean sibship size and the total twinning rate can be considered as a crude estimate of the expected number of sets of twins in a sibship. The same can be said about the twinning parameter in our model. These estimates are in good agreement. If we consider twinning data only, we obtain the geometric distribution, and log (Nk), where Nk is the number of mothers with k twin maternities, is a linear function of the number of recurrences. Graphically, this property can easily be checked. For sibships containing three or more sets of twins, all four populations show higher values than expected, particularly the populations from Stuttgart and Utah, which data also show poor agreement according to a chi 2-test. A more exact model would demand more detailed demographic information, such as distribution of sibship sizes, age-specific twinning rates and temporal variations in twinning. The observed number of mothers in Aland with several recurrences of multiple maternities shows a considerable excess over the expected number as predicted by Peller's rule. The parameters in our model can be estimated by the maximum likelihood method and the obtained model fits the data better then Peller's model.

Female↗
PubMed1990

Pseudoinflammatory fundus dystrophy: a follow-up study.

We have performed a reinvestigation of a family with a presumably autosomal recessive form of pseudoinflammatory dystrophy, which we have followed for 25 years. The symptoms in this family are subretinal haemorrhages appearing at age 13-40 years in the central fundus, resulting in glial cicatrication in the outer retinal layers, progressive myopia and profound choroidal atrophy in the advanced stages of the disease. During the follow-up study, a new affected subject was found in the younger generation, and two collateral cases, who had earlier been considered as probably affected subjects, were now considered to have other fundus affections. The new case is the daughter of an affected female. The possibilities of an autosomal dominant mode of inheritance or pseudodominance are discussed. Extended genealogical studies showed that the parents of all the affected subjects, with the exception of the new case, have their origin in an area which was isolated until recently and have several common ancestors within the last 8-10 generations. Recessive inheritance also logically explains the appearance of the disease in so few other members in the vertical line of the family. To this fundus dystrophy, the rule of Lenz seems to apply: If more or less the same phenotype can be caused by both a recessive and a dominant gene, the phenotype caused by the recessive gene is generally manifested earlier and by more severe symptoms.

Adolescent↗
PubMed1990

Rod-cone dystrophy of the retina. Continuation of a family study described in 1923.

In 1923 Alkio described a sibship with 4 children showing macular dystrophy. In the literature this has been classed among the cone dystrophy group. However, Alkio's patients later became completely blind by the age of 50. According to the hospital records one of them showed marked destruction and pigment degeneration throughout the fundus. The daughter of one of those affected has healthy eyes, but two of her three sons are affected in the same way as their grandfather. They were studied by us in 1987. These two males showed the bull's eye type of macular dystrophy with visual acuity of 20/30 resp 20/50, marked dyschromatopsia, central scotoma in the visual field for weak markers, extinguished ERGs and subnormal EOGs. Dark adaptation was considered pathological especially during the cone phase. The peripheral fundus was within normal limits. The parents of the two patients have a common ancestor born in 1720. Autosomal recessive inheritance is therefore very likely. We think that the disorder is closer to the rod-cone dystrophy group than to cone or cone-rod degenerations.

Adolescent↗
PubMed1990

Standardization of the twinning rate.

There is a great interest in comparing twinning rates. These comparisons can be performed between different time periods for a specific population, between different regions within the same country, and between different populations. However, there are several factors (maternal age, parity, urbanization, etc.) that influence the twinning rate. The most dominant one is maternal age, and because the age distribution of the mother varies, it is necessary to standardize the data to make these comparisons. If we want to compare the twinning rates in different countries, we have to face the problem that the composition of the data from different countries may differ to a great extent. The applicable method is determined by the data of the lowest quality. Often the available data do not allow the traditional (direct and/or indirect) methods of standardization. Under such circumstances other methods have to be used. Earlier, Fellman and Eriksson (1987) proposed and successfully applied a new method. In this article we discuss the standardization problem in more detail. We suggest different methods and apply them to different data on twinning from Australia, Finland, and Baden-Württemberg (West Germany). The new standardization methods give standardized twinning rates similar to the rates obtained by traditional methods. It is noted that, irrespective of standardization method, changes in maternal age alone cannot explain temporal or regional variations in the twinning rate. Other factors that may raise or lower the twinning rate are decreasing parity, sociodemographic changes with increased communication, which causes the breakup of isolates, and deteriorating physical condition of mothers as a result of increased industrialization and urbanization.

Australia↗
PubMed1989

Haplotype and multipoint linkage analysis in Finnish choroideremia families.

Multipoint linkage analysis of choroideremia (TCD) and seven X chromosomal restriction fragment length polymorphisms (RFLPs) was carried out in 18 Finnish TCD families. The data place TCD distal to PGK and DXS72, very close to DXYS1 and DXYS5 (Zmax = 24 at theta = 0) and proximal to DXYS4 and DXYS12. This agrees with the data obtained from other linkage studies and from physical mapping. All the TCD males and carrier females studied have the same DXYS1 allele in coupling with TCD. In Northeastern Finland, 66/69 chromosomes carrying TCD had the same haplotype at loci DXS72, DXYS1, DXYS4, and DXYS12. The same haplotype is seen in only 15/99 chromosomes not carrying TCD. Moreover, in 71/104 non-TCD chromosomes, the haplotype at six marker loci is different from those seen in any of the 76 TCD chromosomes. This supports the previously described hypothesis that the large Northern Finnish choroideremia pedigrees, comprising a total of over 80 living patients representing more than a fifth of all TCD patients described worldwide, carry the same mutation. These linkage and haplotype data provide improved opportunities for prenatal diagnosis based on RFLP studies.

Choroideremia↗