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Genetic determinants of the stress response in cardiovascular disease.

Originating from Hans Selye's general concept, the biological notion of the stress response implicates neuroendocrine and endocrine pathways as well as their cellular mediators as components of the general adaptation syndrome and its consequences. A highly variable degree of response to psychological and physical stresses has been noted in experimental animals and in human populations. Some stressors, such as the "cold pressor test," have been developed as tools for disease prediction. They apply to variable conditions, from hypertension to insulin resistance, but mostly in relation to cardiovascular outcomes. Other environmental factors, including the degree of salt intake, potentiate the stress response in animals and humans. Our group has undertaken to explore the genetic determinants of the stress response in inbred strains, recombinant congenic and congenic strains, as well as founder human populations. We have succeeded, initially, in linking increased body temperature, a major phenotypic response to stress, to the quantitative trait loci (QTL), one at myh3 on chromosome (Chr) 10, one at hsp27 on Chr 12, and one on Chr Y in the rat. The expression of several stress proteins is under the dominant influence of hstf1 at the rat Chr 7 locus (Mit3). The high prevalence of cardiovascular diseases with traits of enhanced stress responsiveness is discussed here in the context of a paradigm, such as hypertension, in the general population.

Animals↗

The inheritance of metabolic flux: expressions for the within-sibship mean and variance given the parental genotypes.

Recent developments have related quantitative trait expression to metabolic flux. The present paper investigates some implications of this for statistical aspects of polygenic inheritance. Expressions are derived for the within-sibship genetic mean and genetic variance of metabolic flux given a pair of parental, diploid, n-locus genotypes. These are exact and hold for arbitrary numbers of gene loci, arbitrary allelic values at each locus, and for arbitrary recombination fractions between adjacent gene loci. The within-sibship, genetic variance is seen to be simply a measure of parental heterozygosity plus a measure of the degree of linkage coupling within the parental genotypes. Approximations are given for the within-sibship phenotypic mean and variance of metabolic flux. These results are applied to the problem of attaining adequate statistical power in a test of association between allozymic variation and inter-individual variation in metabolic flux. Simulations indicate that statistical power can be greatly increased by augmenting the data with predictions and observations on progeny statistics in relation to parental allozyme genotypes. Adequate power may thus be attainable at small sample sizes, and when allozymic variation is scored at a only small fraction of the total set of loci whose catalytic products determine the flux.

Animals↗

QTL analysis of cadmium and zinc accumulation in the heavy metal hyperaccumulator Thlaspi caerulescens.

Thlaspi caerulescens (Tc; 2n = 14) is a natural Zn, Cd and Ni hyperaccumulator species belonging to the Brassicaceae family. It shares 88% DNA identity in the coding regions with Arabidopsis thaliana (At) (Rigola et al. 2006). Although the physiology of heavy metal (hyper)accumulation has been intensively studied, the molecular genetics are still largely unexplored. We address this topic by constructing a genetic map based on AFLP markers and expressed sequence tags (ESTs). To establish a genetic map, an F(2) population of 129 individuals was generated from a cross between a plant from a Pb/Cd/Zn-contaminated site near La Calamine, Belgium, and a plant from a comparable site near Ganges (GA), France. These two accessions show different degrees of Zn and, particularly, Cd accumulation. We analyzed 181 AFLP markers (of which 4 co-dominant) and 13 co-dominant EST sequences-based markers and mapped them to seven linkage groups (LGs), presumably corresponding to the seven chromosomes of T. caerulescens. The total length of the genetic map is 496 cM with an average density of one marker every 2.5 cM. This map was used for Quantitative Trait Locus (QTL) mapping in the F(2). For Zn as well as Cd concentration in root we mapped two QTLs. Three QTLs and one QTL were mapped for Zn and Cd concentration in shoot, respectively. These QTLs explain 23.8-60.4% of the total variance of the traits measured. We found only one common locus (LG6) for Zn and Cd (concentration in root) and one common locus for shoot and root concentrations of Zn (LG1) and of Cd (LG3). For all QTLs, the GA allele increased the trait value except for two QTLs for Zn accumulation in shoot (LG1 and LG4) and one for Zn concentration in root (LG1).

Cadmium↗

Quantitative analysis of activated microglia, ramified and damage of processes in the frontal and temporal lobes of chronic schizophrenics.

Under pathological conditions, microglial cells undergo activation, which is manifested by the expression of histocompatibility locus antigens class II (HLA II) on their surface as well as by proliferation and varied morphological forms. In schizophrenia, characterised by an essential role played by immunological mechanisms, quantitative analysis of activated microglia -- with well-developed ramification (RM), degenerative traits and damaged processes (from their shortening to their complete lack) (DM) -- may contribute to better understanding of schizophrenia etiopathogenesis. Quantitative analysis was performed on slices derived from the frontal and temporal lobes of 9 brains of schizophrenics and 6 control brains. The nonparametric Mann-Whitney U test was used to assess quantitative differences in the distribution of microglia in these regions of the brain. Statistical analyses were performed with STATISTICA 6.5 Programme. In both structures of the brain, the number of activated microglial cells was higher in schizophrenic brains than in control brains. Except for the first layer of the cerebral cortex with the same amounts of RM and DM, the number of DM cells in the remaining regions was several-fold higher than that of RM cells. It is most likely that disturbances in calcium metabolism and energetic balance as well as antibodies produced in the course of schizophrenia are the agents able to trigger a cascade transforming RM into DM. Quantitative differences in RM and DM, observed between the studied structures and cortical regions, could depend not only on functioning of inter-neuronal and inter-structural links. Our study suggests a pivotal role of microglial cells in repair processes and/or etiopathogenesis of schizophrenia and indicates that they undergo substantial damage in the course of chronic schizophrenia.

Adult↗

Genetic analysis of a quantitative trait in a mouse model of polycystic kidney disease.

The development of a variety of powerful tools for genome analysis has facilitated the ability to genetically map loci which contribute to the variation of a quantitative trait. However, the fact that these traits are often determined as a result of complex genetic interactions has made their analysis considerably more difficult then the molecular characterization of qualitative traits that are monogenic in origin. We have described the use of a novel method of chromosomal exclusion to map the recessive mutation juvenile cystic kidney (jck) to mouse chromosome 11 using an intercross between (C57BL/6J x DBA/2J) F1 jck/+ mice. The severity of polycystic kidney disease (PKD) in the intercross progeny, which could be quantitated as a function of kidney size, was significantly more variable than that found in the parental C57BL/6J strain, suggesting that a modifier locus or loci introduced from DBA/2J affects expression of jck. Two regions (one from DBA/2J on chromosome 10 and a second from C57BL/6J on chromosome 1) were found to be associated with inheritance of a more severe PKD phenotype. The finding of a highly significant association of inheritance of a C57BL/6J-related locus with disease severity was unexpected since the PKD phenotype in this inbred background is mild. This result suggests that inheritance in the affected F2 mice of loci from the two different parental backgrounds results in the more severe phenotype, presumably as a consequence of a direct or indirect interaction between their protein products. This type of effect, which is an example of genetic epistasis, will make the molecular characterization of loci that contribute to complex traits markedly more difficult than the analysis of monogenic disorders.

Animals↗

Locating Ath8, a locus for murine atherosclerosis susceptibility and testing several of its candidate genes in mice and humans.

A previous study revealed that the difference in susceptibility to atherosclerotic lesions between inbred mouse strains SM/J and NZB/BlNJ was determined by one major locus (Ath8). In this study a (SM/J x NZB/BlNJ) F(1) x SM/J backcross localized Ath8 by quantitative trait locus mapping to chromosome 4 with a suggestive LOD score of 2.7. This quantitative trait locus (QTL) was confirmed using an (SM/J x NZB/BlNJ) intercross; Ath8 mapped to a 23cM region with a significant LOD score of 3.6. The genes for toll-like receptor 4 (T1r4), arachidonic acid epoxygenase (Cyp2j5), and angiopoietin-like protein 3 (Angptl3) map to this region. These candidate genes were analyzed for expression and sequence differences in the mouse and for associations with cardiovascular traits in human. Sequence analysis of Angptl3 shows a base pair substitution in SM, the susceptible strain, giving rise to an amino acid change in the fibrinogen homology domain of the protein. We found a significant association between ANGPTL3 and atherosclerotic lesions (P < 0.05) in human. These results suggest that Angptl3 is involved in atherosclerosis susceptibility in both mouse and human.

Animals↗

Genetic mapping and QTL analysis of horticultural traits in cucumber ( Cucumis sativus L.) using recombinant inbred lines.

A set of 171 recombinant inbred lines (RIL) were developed from a narrow cross in cucumber ( Cucumis sativus L.; 2n = 2 x = 14) using the determinate ( de), gynoecious ( F), standard-sized leaf line G421 and the indeterminate, monoecious, little-leaf ( ll) line H-19. A 131-point genetic map was constructed using these RILs and 216 F(2) individuals to include 14 SSRs, 24 SCARs, 27 AFLPs, 62 RAPDs, 1 SNP, and three economically important morphological [ F (gynoecy), de (determinate habit), ll (little leaf)] markers. Seven linkage groups spanned 706 cM with a mean marker interval of 5.6 cM. The location of F and de was defined by genetic linkage and quantitative trait locus (QTL) analysis to be associated with SSR loci CSWCT28 and CSWCTT14 at 5.0 cM and 0.8 cM, respectively. RIL-based QTL analysis of the number of lateral branches in three environments revealed four location-independent factors that cumulatively explained 42% of the observed phenotypic variation. QTLs conditioning lateral branching (mlb1.1), fruit length/diameter ratio (ldr1.2) and sex expression (sex1.2) were associated with de. Sex expression was influenced by three genomic regions corresponding to F and de both on linkage Group 1, and a third locus (sex6.1) on linkage Group 6. QTLs conditioning the number of fruit per plant (fpl1.2), the number of lateral branches (mlb1.4) and fruit length/diameter ratio (ldr1.3) were associated with ll. The potential value of these marker-trait associations (i.e., yield components) for plant improvement is portended by the relatively high LOD scores (2.6 to 13.0) and associated R(2) values (1.5% to 32.4%) that are affiliated with comparatively few genetic factors (perhaps 3 to 10).

Chromosome Mapping↗

AFLP and STS tagging of a major QTL for Fusarium head blight resistance in wheat.

Large-scale field screening for Fusarium head blight (FHB) resistance in wheat is difficult because environmental factors strongly influences the expression of resistance genes. Marker-assisted selection (MAS) may provide a powerful alternative. Conversion of amplified fragment length polymorphism (AFLP) markers into sequence-tagged site (STS) markers can generate breeder-friendly markers for MAS. In a previous study, one major quantitative trait locus (QTL) on chromosome 3BS was identified by using EcoRI-AFLP and a recombinant inbred population derived from the cross Ning 7840/Clark. Further mapping with PstI-AFLPs identified five markers that were significantly associated with the QTL. Three of them individually explained 38% to 50% of the phenotypic variation for FHB resistance. Two of them (pAGT/mCTG57, pACT/mCTG136) were linked to the QTL in coupling, and another (pAG/mCAA244) was linked to the QTL in repulsion. Successful conversion of one AFLP marker (pAG/mCAA244) yielded a co-dominant STS marker that explains about 50% of the phenotypic variation for FHB resistance in the population. The STS was validated in 14 other cultivars and is the first STS marker for a FHB resistance QTL converted from an AFLP marker.

Base Sequence↗

Mapping genetic modifiers of epimutation rates identifies VIM2/4 as dosage-sensitive negative regulators of CG methylation maintenance.

Spontaneous epimutations are stochastic gains and losses of cytosine methylation that arise from imperfect maintenance across cell divisions. At CG sites, such epimutations can be inherited across generations in plants and constitute a major source of CG methylation (mCG) diversity. However, why the fidelity of mCG inheritance varies among genotypes, and how this variation relates to steady-state mCG levels, remains poorly understood. Here we tracked DNA methylation over 10 generations in ~400 mutation-accumulation lines derived from ~70 Arabidopsis thaliana Ler&#x2009;&#xd7;&#x2009;Cvi recombinant inbred founders. By treating methylation gain and loss rates as quantitative molecular traits, we mapped a major-effect locus to a Cvi-derived deletion between VARIANT IN METHYLATION (VIM)2 and VIM4, two key components of the METHYLTRANSFERASE 1-dependent mCG maintenance pathway. Lines carrying this deletion showed elevated VIM2/4 (VIM2 and VIM4) expression, a rapid shift of genome-wide mCG towards a lower steady state and reduced fidelity of methylation inheritance across generations. Complementary overexpression and loss-of-function experiments identify VIM2/4 as dosage-sensitive negative regulators of mCG maintenance, in contrast to the canonical positive role of VIM-family proteins in mCG. Together, our results support a punctuated-equilibrium model of DNA methylome evolution, in which naturally segregating modifiers of mCG homeostasis can produce abrupt shifts in methylation state and alter the rate at which heritable epigenetic variation accumulates in plant genomes.

Journal Article↗

QTL analysis of Fusarium head blight resistance using a high-density linkage map in barley.

Fusarium head blight (FHB) resistance was evaluated in a set of recombinant inbred (RI) lines from a cross between Russia 6 (resistant) and H.E.S. 4 (susceptible), which had one of the widest differences of FHB resistance reactions among ca. 5,000 barley germplasm accessions in Okayama University. Field-grown spikes were sampled and inoculated by the 'cut-spike test'. Resistance reactions on the parents and RI lines were scored by eleven grades, from resistant (0) to susceptible (10). Quantitative trait loci (QTL) analysis detected three QTL: two located on the long arm of chromosome 2H, and another on the short arm of chromosome 5H. A QTL located on chromosome 2H was coincident with the vrs1 locus, which governs inflorescence row type. The other QTL on chromosome 2H was positioned in the vicinity of cleistogamy locus (cly1 or Cly2) that determines inflorescence opening/closing. Resistant gene analog (RGA) and expressed sequence tag (EST) markers with homology for disease resistance genes were integrated into the high-density linkage map. Most of these markers were not localized near the identified resistance QTL, except for one RGA marker (FXLRRfor_XLRRrev170) localized in the vicinity of the cly1/Cly2 locus. Five AFLP markers localized in the vicinity of the identified QTL were sequenced to convert them into sequence tagged site (STS) markers. Genotyping of each RI line using two AFLP-STS markers and the vrs1 locus indicated that the RI lines with three Russia 6 QTL alleles exhibited the same level of high FHB resistance reactions as Russia 6. In contrast, RI lines with three susceptible alleles showed reactions close to H.E.S. 4. Therefore, the markers closely linked to the QTL can be efficiently used for the selection of resistance.

Chromosome Mapping↗

Influence of Slc11a1 on the outcome of Salmonella enterica serovar Enteritidis infection in mice is associated with Th polarization.

Genetic analyses identified Ses1 as a significant quantitative trait locus influencing the carrier state of 129S6 mice following a sublethal challenge with Salmonella enterica serovar Enteritidis. Previous studies have determined that Slc11a1 was an excellent candidate gene for Ses1. Kinetics of infection in 129S6 mice and Slc11a1-deficient (129S6-Slc11a1(tm1Mcg)) mice demonstrated that the wild-type allele of Slc11a1 contributed to the S. enterica serovar Enteritidis carrier state as early as 7 days postinfection. Gene expression profiling demonstrated that 129S6 mice had a significant up-regulation of proinflammatory genes associated with macrophage activation at day 10 postinfection, followed by a gradual increase in immunoglobulin transcripts, whereas 129S6-Slc11a1(tm1Mcg) mice had higher levels of immunoglobulins earlier in the infection. Quantitative reverse transcription-PCR revealed an increase in Th1 cytokine (Ifng and Il12) and Th1-specific transcription factor Tbx21 expression during infection in both the 129S6 and 129S6-Slc11a1(tm1Mcg) strains. However, the expression of Gata3, a transcription factor involved in Th2 polarization, Cd28, and Il4 was markedly increased in Slc11a1-deficient mice during infection, suggesting a predominant Th2 phenotype in 129S6-Slc11a1(tm1Mcg) animals following S. enterica serovar Enteritidis infection. A strong immunoglobulin G2a response, reflecting Th1 activity, was observed only in 129S6 mice. All together, these results are consistent with an impact of Slc11a1 on Th cell differentiation during chronic S. enterica serovar Enteritidis infection. The presence of a Th2 bias in Slc11a1-deficient mice is associated with improved bacterial clearance.

Animals↗

Linkage analysis of extremely discordant and concordant sibling pairs identifies quantitative-trait loci that influence variation in the human personality trait neuroticism.

Several theoretical studies have suggested that large samples of randomly ascertained siblings can be used to ascertain phenotypically extreme individuals and thereby increase power to detect genetic linkage in complex traits. Here, we report a genetic linkage scan using extremely discordant and concordant sibling pairs, selected from 34,580 sibling pairs in the southwest of England who completed a personality questionnaire. We performed a genomewide scan for quantitative-trait loci (QTLs) that influence variation in the personality trait of neuroticism, or emotional stability, and we established genomewide empirical significance thresholds by simulation. The maximum pointwise P values, expressed as the negative logarithm (base 10), were found on 1q (3.95), 4q (3.84), 7p (3.90), 12q (4.74), and 13q (3.81). These five loci met or exceeded the 5% genomewide significance threshold of 3.8 (negative logarithm of the P value). QTLs on chromosomes 1, 12, and 13 are likely to be female specific. One locus, on chromosome 1, is syntenic with that reported from QTL mapping of rodent emotionality, an animal model of neuroticism, suggesting that some animal and human QTLs influencing emotional stability may be homologous.

Adult↗

Genetic regulation of gene-specific mRNA by ethanol in vivo and its possible role in ethanol preference in a cross with RI lines in mice.

Relative ethanol preference is a well-recognized phenotype in a number of species, including mice, but the molecular basis for this phenotype remains speculative. We generated novel recombinant inbred (RI) mouse lines from C57BL/6J (ethanol preferring) and BALB/c (ethanol avoiding) strains and evaluated the effect of ethanol feeding on the mRNA levels of three genes (Adh-1, Ahd-2, and Cas-1) of alcohol metabolism. Ethanol feeding affects the mRNA levels of all three genes in both a gene- and a genotype-specific manner. The effect of ethanol feeding on Ahd-2 mRNA, in particular, is highly correlated with the relative ethanol acceptance of the genotypes. DNA sequencing of approximately 500 bp of the 5' upstream region of the Ahd-2 gene has yielded identical sequence for the two strains and the genetically determined associated factors are hypothesized to be regulatory proteins. Quantitative trait locus analysis on the RI lines should lead to the molecular characterization and mapping of such gene-specific regulatory factors.

Alcohol Dehydrogenase↗

Cloning and chromosomal mapping of the murine norepinephrine transporter.

The norepinephrine (NE) transporter (NET), a target of many clinically prescribed antidepressants, regulates noradrenergic neurotransmission by efficiently clearing NE from synaptic spaces after release. To advance our understanding of NET gene structure, regulation, and potential associations with complex behavioral trait loci, we amplified a mouse norepinephrine transporter (mNET) cDNA from placenta total RNA and utilized mNET probes to isolate and characterize the mNET gene. Inferred translation of the major open reading frame of the mNET cDNA predicts a 617-amino acid protein with 12 putative membrane-spanning regions and 94% identity to human NET. The coding exons of the mNET cDNA were found to be spread across >36 kb of 129/Svj genomic DNA, with exon-intron boundaries bearing consensus gt/ag splice sites. Sequence upstream (202 bp) of the inferred translation initiation site matched the sequence of 5' rapid amplification of cDNA ends products from brain mRNA with no evidence for intervening introns and is preceded by a TATA box and canonical transcriptional regulatory elements that may play a role in mNET expression in vivo. Probes derived from mNET cDNA identified species-specific MspI restriction fragment length variations within the mNET gene that were utilized to position the gene (Slc6a5) to murine chromosome 8, one recombinant distal to D8Mit15. This site is within a recently defined quantitative trait locus defined for ethanol sensitivity in LSXSS recombinant inbred mice, Lore4. The status of Slc6a5 as a candidate gene for alcohol sensitivity is discussed with respect to studies noting ethanol-induced alterations in brain NE receptors, NE receptor-linked adenylate cyclase, and NE transport.

Amino Acid Sequence↗

Linkage analysis of susceptibility to hyperoxia. Nrf2 is a candidate gene.

A strong role for reactive oxygen species (ROS) has been proposed in the pathogenesis of a number of lung diseases. Hyperoxia (> 95% oxygen) generates ROS and extensive lung damage, and has been used as a model of oxidant injury. However, the precise mechanisms of hyperoxia-induced toxicity have not been completely clarified. This study was designed to identify hyperoxia susceptibility genes in C57BL/6J (susceptible) and C3H/HeJ (resistant) mice. The quantitative phenotypes used for this analysis were pulmonary inflammatory cell influx, epithelial cell sloughing, and hyperpermeability. Genome-wide linkage analyses of intercross (F2) and recombinant inbred cohorts identified significant and suggestive quantitative trait loci on chromosomes 2 (hyperoxia susceptibility locus 1 [Hsl1]) and 3 (Hsl2), respectively. Comparative mapping of Hsl1 identified a strong candidate gene, Nfe2l2 (nuclear factor, erythroid derived 2, like 2 or Nrf2) that encodes a transcription factor NRF2 which regulates antioxidant and phase 2 gene expression. Strain-specific variation in lung Nrf2 messenger RNA expression and a T --> C substitution in the B6 Nrf2 promoter that cosegregated with susceptibility phenotypes in F2 animals supported Nrf2 as a candidate gene. Results from this study have important implications for understanding the mechanisms through which oxidants mediate the pathogenesis of lung disease.

Animals↗

Natural variation in partial resistance to Pseudomonas syringae is controlled by two major QTLs in Arabidopsis thaliana.

BACKGROUND: Low-level, partial resistance is pre-eminent in natural populations, however, the mechanisms underlying this form of resistance are still poorly understood. METHODOLOGY/PRINCIPAL FINDINGS: In the present study, we used the model pathosystem Pseudomonas syringae pv. tomato DC3000 (Pst) - Arabidopsis thaliana to study the genetic basis of this form of resistance. Phenotypic analysis of a set of Arabidopsis accessions, based on evaluation of in planta pathogen growth revealed extensive quantitative variation for partial resistance to Pst. It allowed choosing a recombinant inbred line (RIL) population derived from a cross between the accessions Bayreuth and Shahdara for quantitative genetic analysis. Experiments performed under two different environmental conditions led to the detection of two major and two minor quantitative trait loci (QTLs) governing partial resistance to Pst and called PRP-Ps1 to PRP-Ps4. The two major QTLs, PRP-Ps1 and PRP-Ps2, were confirmed in near isogenic lines (NILs), following the heterogeneous inbred families (HIFs) strategy. Analysis of marker gene expression using these HIFs indicated a negative correlation between the induced amount of transcripts of SA-dependent genes PR1, ICS and PR5, and the in planta bacterial growth in the HIF segregating at PRP-Ps2 locus, suggesting an implication of PRP-Ps2 in the activation of SA dependent responses. CONCLUSIONS/SIGNIFICANCE: These results show that variation in partial resistance to Pst in Arabidopsis is governed by relatively few loci, and the validation of two major loci opens the way for their fine mapping and their cloning, which will improve our understanding of the molecular mechanisms underlying partial resistance.

Arabidopsis↗

Genetic and structural analysis of the basolateral amygdala complex in BXD recombinant inbred mice.

The amygdala integrates and coordinates emotional and autonomic responses. The genetics that underlie variation in amygdala structure may be coupled to variation in levels of aggression, fear, anxiety, and affiliated behaviors. We systematically quantified the volume and cell populations of the basolateral amygdala complex (BLAc) across 35 BXD recombinant inbred (RI) lines, the parental strains--C57BL/6J (B6) and DBA/2J (D2)--and F1 hybrids (n cases=199, bilateral analysis). Neuron number and volume vary 1.7- to 2-fold among strains (e.g., neuron number ranged from 88,000 to 170,000). Glial and endothelial populations ranged more widely (5- to 8-fold), in part because of higher technical error. A quantitative trait locus (QTL) for the BLAc size is located on chromosome (Chr) 8 near the Large gene. This locus may also influence volume of other regions including hippocampus and cerebellum. Cell populations in the BLAc appear to be modulated more weakly by loci on Chrs 11 and 13. Candidate genes were selected on the basis of correlation with BLAc traits, chromosomal location, single nucleotide polymorphism (SNP) density, and expression patterns in the Allen Brain Atlas. Neurod2, a gene shown to be significant for the formation of the BLAc by knockout studies, is among the candidates genes. Other candidates include Large, and Thra. Responses to drugs of abuse and locomotor activity were the most notable behavioral correlates of the BLAc traits.

Amygdala↗

Interstitial deletion of the proximal long arm of chromosome 4 associated with father-child incompatibility within the Gc-system: probable reduced gene dosage effect and partial piebald trait.

Gc-system typing by isoelectric focusing polyacrylamide gel electrophoresis and quantitative assays were carried out on a patient with a karyotype of 46,XY,del(4)(q12q21.1) and on his parents with normal chromosomes. Although a father-child incompatibility within the Gc-system suggested that its locus is on segment 4q12-13, the serum concentration of vitamin D binding protein in the patient and his father were only about half of that of his mother and control individuals. The possibility of interference of a silent allele in the child could not be excluded. Associated congenital partial leukodermia appeared to be an expression of a partial piebald trait.

Chromosome Banding↗