Genome-wide Association Meta-analysis of Childhood and Adolescent Internalizing Symptoms

OBJECTIVE

To investigate the genetic architecture of internalizing symptoms in childhood and adolescence.

METHOD

In 22 cohorts, multiple univariate genome-wide association studies (GWASs) were performed using repeated assessments of internalizing symptoms, in a total of 64,561 children and adolescents between 3 and 18 years of age. Results were aggregated in meta-analyses that accounted for sample overlap, first using all available data, and then using subsets of measurements grouped by rater, age, and instrument.

RESULTS

The meta-analysis of overall internalizing symptoms (INToverall) detected no genome-wide significant hits and showed low single nucleotide polymorphism (SNP) heritability (1.66%, 95% CI = 0.84-2.48%, neffective = 132,260). Stratified analyses indicated rater-based heterogeneity in genetic effects, with self-reported internalizing symptoms showing the highest heritability (5.63%, 95% CI = 3.08%-8.18%). The contribution of additive genetic effects on internalizing symptoms appeared to be stable over age, with overlapping estimates of SNP heritability from early childhood to adolescence. Genetic correlations were observed with adult anxiety, depression, and the well-being spectrum (|rg| > 0.70), as well as with insomnia, loneliness, attention-deficit/hyperactivity disorder, autism, and childhood aggression (range |rg| = 0.42-0.60), whereas there were no robust associations with schizophrenia, bipolar disorder, obsessive-compulsive disorder, or anorexia nervosa.

CONCLUSION

Genetic correlations indicate that childhood and adolescent internalizing symptoms share substantial genetic vulnerabilities with adult internalizing disorders and other childhood psychiatric traits, which could partially explain both the persistence of internalizing symptoms over time and the high comorbidity among childhood psychiatric traits. Reducing phenotypic heterogeneity in childhood samples will be key in paving the way to future GWAS success.

Consequential Impacts of Tobacco Use on Cognitive Performance

Tobacco use represents a pernicious lifestyle factor that may influence processes of aging, including cognitive functioning. As individuals tend to start smoking before adulthood, it may serve as an important factor in cognitive development and maintenance. We explored smoking history-cognition associations in a sample approaching midlife. Study data was derived from the Colorado Adoption/Twin Study of Lifespan behavioral development and cognitive aging (CATSLife 1; N = 1195 [53% F]; x̄age = 33.2 years, SD = 5.0). All cognitive measures were t-scored covering working memory, spatial reasoning, processing speed (WAIS-III Digit Span, Block Design, and Digit Symbol, and Colorado Perceptual Speed) and episodic memory domains (Picture Memory, immediate and delayed). Tobacco use measures included ever-smokers, current-smokers, and log-transformed packyears. Mixed-effects regression models were applied, accounting for sex, age, race, ethnicity, and clustering among siblings. Tobacco use was associated with worse episodic memory, spatial and speed performance, but not working memory. When educational attainment was included, patterns remained consistent though attenuated. Results suggested current-smokers scored 0.27 to 0.36 SD lower than non-smokers on speed and spatial reasoning tasks. Episodic memory performance was reduced by approximately 0.07 to 0.1 SD per log packyear. In a sample approaching midlife, the harmful impacts of tobacco use on cognitive performance may be already apparent with cumulative impacts of packyears on episodic memory and current smoking associated with spatial and speed performance. This work helps to elucidate the temporal associations of an important lifestyle factor that may influence cognitive functioning prior to midlife.

Genetic association study of childhood aggression across raters, instruments, and age

Childhood aggressive behavior (AGG) has a substantial heritability of around 50%. Here we present a genome-wide association meta-analysis (GWAMA) of childhood AGG, in which all phenotype measures across childhood ages from multiple assessors were included. We analyzed phenotype assessments for a total of 328 935 observations from 87 485 children aged between 1.5 and 18 years, while accounting for sample overlap. We also meta-analyzed within subsets of the data, i.e., within rater, instrument and age. SNP-heritability for the overall meta-analysis (AGGoverall) was 3.31% (SE = 0.0038). We found no genome-wide significant SNPs for AGGoverall. The gene-based analysis returned three significant genes: ST3GAL3 (P = 1.6E-06), PCDH7 (P = 2.0E-06), and IPO13 (P = 2.5E-06). All three genes have previously been associated with educational traits. Polygenic scores based on our GWAMA significantly predicted aggression in a holdout sample of children (variance explained = 0.44%) and in retrospectively assessed childhood aggression (variance explained = 0.20%). Genetic correlations (rg) among rater-specific assessment of AGG ranged from rg = 0.46 between self- and teacher-assessment to rg = 0.81 between mother- and teacher-assessment. We obtained moderate-to-strong rgs with selected phenotypes from multiple domains, but hardly with any of the classical biomarkers thought to be associated with AGG. Significant genetic correlations were observed with most psychiatric and psychological traits (range [Formula: see text]: 0.19-1.00), except for obsessive-compulsive disorder. Aggression had a negative genetic correlation (rg = ~-0.5) with cognitive traits and age at first birth. Aggression was strongly genetically correlated with smoking phenotypes (range [Formula: see text]: 0.46-0.60). The genetic correlations between aggression and psychiatric disorders were weaker for teacher-reported AGG than for mother- and self-reported AGG. The current GWAMA of childhood aggression provides a powerful tool to interrogate the rater-specific genetic etiology of AGG.

Leveraging genome-wide data to investigate differences between opioid use vs. opioid dependence in 41,176 individuals from the Psychiatric Genomics Consortium

To provide insights into the biology of opioid dependence (OD) and opioid use (i.e., exposure, OE), we completed a genome-wide analysis comparing 4503 OD cases, 4173 opioid-exposed controls, and 32,500 opioid-unexposed controls, including participants of European and African descent (EUR and AFR, respectively). Among the variants identified, rs9291211 was associated with OE (exposed vs. unexposed controls; EUR z = -5.39, p = 7.2 × 10-8). This variant regulates the transcriptomic profiles of SLC30A9 and BEND4 in multiple brain tissues and was previously associated with depression, alcohol consumption, and neuroticism. A phenome-wide scan of rs9291211 in the UK Biobank (N > 360,000) found association of this variant with propensity to use dietary supplements (p = 1.68 × 10-8). With respect to the same OE phenotype in the gene-based analysis, we identified SDCCAG8 (EUR + AFR z = 4.69, p = 10-6), which was previously associated with educational attainment, risk-taking behaviors, and schizophrenia. In addition, rs201123820 showed a genome-wide significant difference between OD cases and unexposed controls (AFR z = 5.55, p = 2.9 × 10-8) and a significant association with musculoskeletal disorders in the UK Biobank (p = 4.88 × 10-7). A polygenic risk score (PRS) based on a GWAS of risk-tolerance (n = 466,571) was positively associated with OD (OD vs. unexposed controls, p = 8.1 × 10-5; OD cases vs. exposed controls, p = 0.054) and OE (exposed vs. unexposed controls, p = 3.6 × 10-5). A PRS based on a GWAS of neuroticism (n = 390,278) was positively associated with OD (OD vs. unexposed controls, p = 3.2 × 10-5; OD vs. exposed controls, p = 0.002) but not with OE (p = 0.67). Our analyses highlight the difference between dependence and exposure and the importance of considering the definition of controls in studies of addiction.

Using Cloninger's temperament scales to predict substance-related behaviors in adolescents: a prospective longitudinal study

BACKGROUND AND OBJECTIVES

We tested one of Cloninger's temperament theories - that high novelty seeking (NS), along with low harm avoidance (HA), reward dependence (RD), and persistence (PE), predicts early-onset substance problems.

METHODS

In a community-based sample of 777 adolescents examined at two time points (mean age 13 and 18, respectively), we examined whether Cloninger's four temperament dimensions at wave 1 predicted five substance-related outcomes at wave 2: age of initiation for cigarettes, alcohol, and illicit drugs, number of substance classes tried, and total number of DSM-IV substance use disorder (SUD) symptoms.

RESULTS

Cloninger's predicted temperament pattern did significantly predict the number of SUD symptoms at wave 2. For initiation of cigarettes/illicit drugs and number of substance classes tried, HA/NS/PE fit the pattern, but RD did not. For onset of alcohol, only NS and PE fit Cloninger's prediction. Results for NS and PE were most consistent.

CONCLUSIONS AND SCIENTIFIC SIGNIFICANCE

Overall, this study provides evidence that Cloninger's theory may hold true for predicting problem use more than for predicting "use" or experimentation. In addition, youth with high novelty seeking and low persistence may find substances especially reinforcing, and identifying these youth and intervening before initiation has occurred may reduce the risk of future substance-related problems.

Externalizing behaviors are associated with SNPs in the CHRNA5/CHRNA3/CHRNB4 gene cluster

There is strong evidence for shared genetic factors contributing to childhood externalizing disorders and substance abuse. Externalizing disorders often precede early substance experimentation, leading to the idea that individuals inherit a genetic vulnerability to generalized disinhibitory psychopathology. Genetic variation in the CHRNA5/CHRNA3/CHRNB4 gene cluster has been associated with early substance experimentation, nicotine dependence, and other drug behaviors. This study examines whether the CHRNA5/CHRNA3/CHRNB4 locus is correlated also with externalizing behaviors in three independent longitudinally assessed adolescent samples. We developed a common externalizing behavior phenotype from the available measures in the three samples, and tested for association with 10 SNPs in the gene cluster. Significant results were detected in two of the samples, including rs8040868, which remained significant after controlling for smoking quantity. These results expand on previous work focused mainly on drug behaviors, and support the hypothesis that variation in the CHRNA5/CHRNA3/CHRNB4 locus is associated with early externalizing behaviors.

Electrically switchable reflection gratings in polymer dispersed liquid crystals

Electrically switchable volume reflection holograms were written by inhomogeneous illumination of a prepolymer syrup containing a nematic liquid crystal and a multifunctional acrylate monomer. Switchable holograms are diffractive optics structures and the diffraction efficiency can be controlled by the application of an electric field. Reflection gratings with grating spacing varying between 0.16-0.27 µm were made during the phase separation of liquid crystals from the fast curing prepolymer syrup. The reflection efficiency of the holograms were electrically modulated with the applied field of ∼10-15V/µm. Real time study of the grating formation revealed that the maximum efficiency is reached in ∼15 seconds. The shrinkage of the host polymer during grating formation resulted in the blue shift of the reflection notch. The response time of the grating in an electric field is ∼50 µs. Low voltage scanning electron microscope studies showed the presence of discrete nematic droplet domains of sizes 30-60 nm in liquid crystal rich region.

An item response theory analysis of DSM-IV conduct disorder

OBJECTIVE

We examined DSM-IV conduct disorder (CD) symptom criteria in a community sample of male and female adolescents to evaluate the extent to which DSM-IV criteria characterize the range of severity of adolescent antisocial behavior within and across sex.

METHOD

Interviews were conducted with 3,208 adolescents between the ages of 11 and 18 years using the Diagnostic Interview Schedule for Children. Item response theory analyses were performed to obtain severity and discrimination parameters for each of the lifetime DSM-IV CD symptom criteria. In addition, item response theory-based differential item functioning analyses were conducted to examine the extent to which the symptom criteria function similarly across sex.

RESULTS

The DSM-IV CD symptom criteria are useful and meaningful indicators of severe adolescent antisocial behavior. A single item ("Steal without Confrontation") was a poor indicator of severe antisocial behavior. The CD symptom criteria function similarly across sex; however, three items had significantly different severity parameters.

CONCLUSIONS

The DSM-IV CD criteria are informative as categorical and continuous measures of severe adolescent antisocial behavior; however, some CD criteria display sex bias.

Common and specific genetic influences on aggressive and nonaggressive conduct disorder domains

OBJECTIVE

To explore the genetic and environmental influences on DSM-IV conduct disorder (CD) aggressive and nonaggressive subscales, taking into account age and sex differences.

METHOD

A community sample of 1,100 twin pairs (ages 11-18) was interviewed using the Diagnostic Interview Schedule for Children. Bivariate analyses, using variable threshold models accounting for age and sex differences, were used to determine the extent to which the genetic and environmental influences on aggressive and nonaggressive CD domains are shared or unique.

RESULTS

The phenotypic correlation between aggressive and nonaggressive CD domains was 0.32. The most parsimonious bivariate model included additive genetic effects and nonshared environmental effects only (AE model).

CONCLUSIONS

The results of behavior genetic model fitting suggest that the DSM-IV CD domains are influenced by unique genetic and environmental factors, but also share some common genetic and environmental influences. A large percentage of the covariation (61%) is caused by genetic factors. These results are consistent with a previous report on the bivariate heritability of aggressive and nonaggressive antisocial behavior, but extend the findings to DSM-IV domains.

Population stratification in the candidate gene study: fatal threat or red herring?

Advances in molecular genetics have provided behavioral scientists with a means of investigating the influence of genetic factors on human behavior. Unfortunately, recent candidate gene studies have produced inconsistent results, and a frequent scapegoat for the lack of replication across studies is the threat of population stratification. This review of the literature on population stratification suggests that the threat may be a red herring. Reliable findings will require improved specification and measurement of the behavioral phenotypes in question, a renewed focus on internal validity, and the specification and testing of genetic factors in the context of longitudinal multivariate models. In this respect, behavioral scientists are well suited to investigating genetic factors that influence psychological mechanisms.

High-performance liquid chromatographic separation and quantitation of glycosylated hemoglobin A2 as an alternate index of glycemic control

By a combination of DEAE-cellulose chromatography and cation-exchange high-performance liquid chromatography glycosylated components of hemoglobin (Hb) A2 were separated and quantitated from persons with diabetes and some common hemoglobinopathies. Hb A2Ic values correlated well with total glycosylated Hb levels assayed by affinity chromatography, and Hb AIc, Hb SIc and Hb CIc levels, determined by high-performance liquid chromatography. The results indicate that Hb A2Ic may serve as an alternate index of glycemic control.

High-pressure liquid chromatographic separation of glycosylated and acetylated minor hemoglobins in newborn infants and in patients with sickle cell disease

High-pressure liquid chromatography on a synchropak CM-300 column was used for separation and quantitation of glycosylated and acetylated minor hemoglobins and major hemoglobins in 15 newborn infants, 17 patients with sickle cell anemia and one each with SC condition, CC disease, Hb S heterozygosity, and Hb C heterozygosity. Hemoglobin Bart's, Fla1, Fla2, Flb, Flc, FO, Ald, AO, and A2 have been separated from newborn infants. Similarly, hemoglobins Fla, Flb, Flc, FO, Sla+b, Slc, A2, Sld, and SO were separated from patients with SS condition. Minor hemoglobins in all the samples were also separated by conventional Bio-Rex 70 chromatographic methods. The percentages of the various hemoglobin components determined by high-pressure liquid chromatography agreed rather well with those obtained by Bio-Rex 70 chromatography. However, the quality of the resolutions and the sharpness of the peaks were, in general, superior with the high-pressure liquid chromatography approach, which is much faster, requires significantly less sample than Bio-Rex 70 chromatography, and is particularly suitable for fast analytical chromatography of minor and major hemoglobins.

Glycosylated hemoglobins in heterozygotes and homozygotes for hemoglobin C with or without diabetes

Glycosylated hemoglobin in red blood cell hemolysates of five patients homozygous for CC, 18 patients with SC condition, and 13 patients heterozygous for Hb C with or without insulin-dependent diabetes mellitus were separated by Bio-Rex 70 chromatography. The various glycosylated components were identified by analysis of the hemoglobin components for ketoamine and phosphate, in vitro glycosylation studies, and by the quantitative differences in the minor components between the participants with and without diabetes. The percentages of Hb A1a + b, Hb A1c, and Hb C1c were significantly increased in the Hb C heterozygote with diabetes. Similarly, the percentages of Hb S1a + b and Hb S1c were elevated in the SC patient with diabetes. It was noteworthy that the levels of these components became normal after adequate control of diabetes. Moreover, the levels of Hb C1c in the CC participants and Hb S1c (Hb S1c/total Hb S) in the SC patients were significantly higher than the Hb S1c levels previously reported in patients with sickle cell anemia. These findings might reflect the fact that CC and SC patients have less severe hemolytic anemia. Moreover, the relative proportions of Hb A1c and Hb C1c were nearly the same in Hb C heterozygotes, which indicated that Hb A and Hb C were glycosylated in vivo to approximately the same extent.

Changes in glycosylated hemoglobins with red cell aging in normal and diabetic subjects and in newborn infants of normal and diabetic mothers

To determine red cell age-related changes in the formation of glycosylated (glyco) hemoglobins (Hbs), red cells were fractionated by dextran 40 density gradient centrifugation and glyco Hbs determined by both Bio-Rex 70 cation exchange and phenylboronate-agarose affinity chromatographic methods. Blood samples from a normal adult, adults with White's class A diabetes and insulin dependent diabetes mellitus (IDDM), and newborns of normal and diabetic women were used for this study. Red cell fractions from the newborns and the adults showed a steady increase in the levels of glyco Hb determined by the affinity method with increasing red cell density. In the newborns, the absolute levels and the increase of glyco Hb were smaller than in the adults, probably because of decreased red cell survival in fetuses compared to adults. The glyco Hb value for each cell fraction was significantly higher in the adult with IDDM and in the newborns of diabetic women. In the adults, the levels of Hb Ala + b and Hb Alc determined by Bio-Rex 70 chromatography also showed an increase with increasing red cell age. In the newborns, Hb Flc, which contains predominantly acetylated and some glycosylated Hb F, showed only a small increase with increasing red cell age over and above that due to a concomitant increase in Hb F. On the contrary, Hb Fla + b, which contains mostly glyco Hb F, showed a larger increase. The results confirm that glycosylation, but not acetylation, of Hb F takes place over the entire lifespan of red cells.

Application of affinity chromatography for separation and quantitation of glycosylated hemoglobins

The use of m-aminophenylboronic acid immobilized on agarose as the affinity matrix for the separation and quantitation of Glyco Hb has been investigated. The glyco fraction isolated from the affinity columns contained about 10% Hb A1a + b, 52% Hb A1c, and 38% Hb A0-like glyco components. The nonglyco fraction had major portions of Hb A1a + b and Hb A0 and a small amount of Hb A1c (also contained Hb F). In normals and diabetic patients, the comparison of the affinity method with the ion-exchange chromatographic, fluorometric, and colorimetric methods showed good correlation. The affinity method also showed acceptable precision and reproducibility. The presence of labile aldimine did not influence the affinity method because it seems that only the stable ketoamine was bound to the affinity gel and thus separated by this method. Moreover, this method was less sensitive to variations in column temperature and sample age. Glyco Hb levels were determined in newborn infants and in adults with various hemoglobinopathies. The results indicated that the presence of Hb F, Hb S, and Hb C did not affect the glyco Hb determinations. Thus the affinity chromatographic approach has wider application than ion-exchange chromatography and is, at the same time, much simpler and faster than the chemical methods.

Demonstration of a minor hemoglobin with modified alpha chains and additional modified hemoglobins in normal and diabetic adults

We have attempted to separate various hemoglobins in 10 normal and 11 diabetic persons by Bio-Rex 70 chromatography at 4 degrees C with an exponentially increasing sodium phosphate gradient. Minor hemoglobins, namely AIa1, AIa2, AIb1, AIb2, AIb3, AIc, AId1, AId2 and AId3, have been separated and eluted in that order. Most of these minor hemoglobins were newly observed and could not be detected by the previous chromatographic techniques. On the basis of colorimetric assay protein-bound ketoamine was present in all the minor hemoglobins, which was confirmed by chromatographic separation of hemoglobins after reduction with NaB3H4. All the minor hemoglobins, with the exception of Hb AIa1, HbIa2, and Hb AIb1, showed a 2-fold increase in the diabetic patients. Hb AIc (5.0% in normals; 9.0% in diabetics) and Hb AId3 (1.9% in normals; 3.2% in diabetics) were present in the largest amounts. Both Hb AId3 and Hb Ao showed a decrease in oxygen affinity in the presence of 2,3-diphosphoglycerate, whereas Hb AIc showed no effect. Separation of globin chains by cellulose acetate electrophoresis at pH 8.6 showed that the cathodal mobility of the alpha chains of Hb AId3 was slower than those of Hb Ao. Glycosylation of Hb with [14C]glucose followed by separation of hemoglobins by two Bio-Rex 70 chromatographic methods indicated that the minor Hb formed by glycosylation of the alpha-chain amino-terminus was separated from Hb Ao, while the minor hemoglobins formed by the glycosylation of epsilon-NH2 groups chromatographed with Hb Ao.

Affinity chromatographic quantitation of glycosylated hemoglobin in newborn infants

Levels of glycosylated hemoglobin (glyco Hb) were determined in 45 newborn infants by affinity chromatography on phenylboronate-agarose gel and found to correlate well with the results obtained by two chemical methods. However the percentages of Hb FIa+b and Hb FIc determined by Bio-Rex 70 chromatography did not correlate with the glyco Hb values. The glyco Hb levels in the newborns were significantly lower than in the adults. Rechromatography of the glyco and nonglyco Hb fractions on Bio-Rex 70 columns indicated that Hb FO-like glyco Hb (presumably formed by glycosylation of the alpha chain amino terminus and epsilon-amino groups of lysyl amino acids) constituted about 60% of the glyco Hb fraction, whereas both Hb FIc and Hb FIa+b components contained only small portions of the glyco Hb.

Modification of sickle hemoglobin by acetaldehyde and its effect on oxygenation, gelation and sickling

Erythrocytes from sickle cell anemia patients and chromatographically purified Hb S0 were incubated with 0.25 to 120 mM acetaldehyde for 15 min to 6 h at different temperatures and pH. Several hemoglobin adducts stable to dialysis were separated by Biorex 70 chromatography and the proportions of the adducts formed were dependent on the period of incubation, acetaldehyde concentration, pH and temperature. Acetaldehyde treatment showed an increase in solubility, minimum gelling concentration and oxygen affinity and a decrease in sickling which showed a dependence on Hb S modification. With 0.25 to 1 mM acetaldehyde, significant inhibition of sickling was observed without any effect on the physical characteristics of the hemoglobin molecule. Acetaldehyde may act as a gelation inhibitor as well as a cell sickling inhibitor.

Synthesis of the minor fetal hemoglobin Fic in colonies of erythropoietic precursors isolated from human umbilical cord blood

The biosynthesis of the minor hemoglobin FIc, which contains acetylated gamma chains, and the major hemoglobin Fo was studied during erythroid cell differentiation and maturation in cultures of erythroid precursors isolated from five human umbilical cord blood samples. A gradual decrease in the synthesis of Hb FIc was observed during the maturation of the erythroid cells when cultured from 7 to 15 days. The synthesis of Hb Fo did not show a consistent change; however, the relative synthesis of Hb FIc was the highest in the 7-day-old colonies and decreased at day 15 to levels observed in the reticulocytes. The addition of sodium butyrate, which is known to promote histone acetylation, significantly increased the synthesis of Hb FIc in 7-day-old colonies.

Synthesis of hemoglobin chains in adult and newborn goats: possible influence of the beta c synthesis on the production of alpha chains

The rates of in vitro synthesis of hemoglobin alpha and non-alpha chains were determined in adult goats during blood loss anemia and in newborn goats during postnatal development. The reticulocytes were incubated in a medium supporting protein synthesis and containing [14C] leucine. The hemoglobin chains were separated by CM-cellulose chromatography. The adult animals responded to the phlebotomy with a production of nearly 100% beta C chain about 10 days after the start of the experiment. Severe anemia and the production of beta C chain was accompanied by a significant increase in the alpha/non-alpha synthesis ratio. The gamma chain production in the newborns declined rapidly after birth and was completely replaced by that of the beta C chain in 7-10 days. No significant difference in the relative synthesis of the three types of alpha chain was observed during this period. Goats with either a homozygosity for the I alpha or I alpha B chains synthesize the I alpha (or I alpha B) and II alpha chains at a ratio of 3:1. When a heterozygosity for I alpha B chains is present the I alpha:I alpha B:II alpha ratio approximates 2:1:1. Results of kinetic studies suggest that the II alpha chains are synthesized at a slower rate than the II alpha chains. The difference in the alpha/non-alpha ratio during severe anemia may be due to a decreased production of beta C chains. No significant difference in the relative synthesis of the I alpha, I alpha B, and II alpha chains was observed between the anemic adult animal and the newborn goat or the growing kid.

Minor (glycosylated) hemoglobins in cord blood of infants of normal and diabetic mothers

The levels of minor (glycosylated) hemoglobins in maternal blood during labor and in cord blood at delivery were determined in four groups of women: 20 normal, 22 probably normal, 20 Class A diabetic, and eight overt diabetic women. Maternal HbA, was not significantly increased in the diabetic patients, thereby reflecting adequate metabolic control. In the cord blood, the percentage of the minor hemoglobin HbF1c, which has been shown to be a mixture of acetylated glycosylated HbF, and the ratios HbF1c/HbF and HbA1/hbA were significantly increased in fetuses delivered of diabetic mothers. This supports the view that these fetuses are hyperglycemic in utero. However, there was no correlation between cord blood glycosylated hemoglobins and the birth weight ratio, a sensitive indicator of relative changes in the birth weight.

Heterozygosity and homozygosity for the high oxygen affinity hemoglobin Tarrant or alpha 126 (H9) Asp replaced by Asn in two Mexican families

Two Mexican families from the State of Jalisco have been studied in which 11 members were carriers of Hb Tarrant. Ten subjects were Hb Tarrant heterozygotes producing about 25% of the abnormal hemoglobin. One 9-year-old boy was homozygous for Hb Tarrant. About 50% of his hemoglobin was of the variant type. The heterozygotes had mild erythrocytosis which was considerably more severe in the homozygote. The average P50 value for blood of the heterozygote was 15.1 mm Hg (controls: 22.5 mm Hg) while this value was decreased to 9 mm Hg in the homozygote. The clinical condition of the homozygote is compatible with a mild chronic tissue hypoxia.

Is the trimodality of Hb Leslie (alpha 2 beta 2 131 Gln---O) in heterozygotes the result of a variable number of active alpha-chain genes? Evidence for posttranslational control of hemoglobin synthesis

Whether the trimodality in the relative concentration of the hemoglobin variant Hb Leslie in heterozygotes (Huisman, Hemoglobin 1:349-382, 1977) is due to a polymorphism of the alpha-chain structural genes was investigated by conventional incubation of reticulocytes with 14C-leucine. In addition, an aliquot from each of the incubations was incubated under the same conditions but without isotope. Three Hb Leslie heterozygotes with presumably four, three (heterozygous alpha-thalassemia-2), and two (homozygous alpha-thalassemia-2) active alpha-chain genes and with 33%, 22% and 11% Hb Leslie respectively, and one patient with the Hb Leslie beta(0)-thalassemia condition with more than 85% Hb Leslie were studied. The data indicate that betaLeslie chains have a lower affinity for alpha chains that betaA chains. A concomitant alpha-chain deficiency results in a reduced incorporation of betaLeslie chains into the tetrameric Hb Leslie molecules, while the quantity of Hb Leslie produced correlates with the degree of alpha-chain deficiency. Excess of betaLeslie chains is preferentially degraded.

An improved chromatographic procedure for quantitation of human fetal hemoglobin

The DEAE-cellulose chromatographic procedure which uses glycine-KCN-NaCl solutions as Developers and a NaCl gradient to elute the hemoglobin zones was found to be useful for the quantitation of Hb F in samples containing Hb A, provided the level of Hb F exceeds 2 percent. The method has been evaluted through a study of artificial mixtures and of blood samples from patients with various disorders. The data have been compared with results obtained by four other procedures that are used for the quantitation of Hb F.

Separation of human hemoglobins by DEAE-cellulose chromatography using glycine-KCN-NaC1 developers

This chromatographic procedure uses DEAE-cellulose as ion exchanger and glycine-KCN-NaC1 solutions as developers. Blood samples from several adults and newborn infants with alpha, beta, delta, or gamma chains variants have been analysed. The hemoglobins are eluted as compact and symmetrical zones, and the separation of many hemoglobin types is greatly improved. The procedure is relatively fast, simple, and inexpensive.