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Familial clustering of impaired spermatogenesis: no evidence for a common genetic inheritance pattern.

BACKGROUND: The aetiology of impaired spermatogenesis is unknown in the majority of cases. Evidence of a contribution of genetic factors is still scarce. Therefore, the aim of our study was to assess whether male factor subfertility due to impaired spermatogenesis has a familial component and to test different genetic models of inheritance. METHODS: Cases were all men with severe idiopathic impaired spermatogenesis attending our fertility clinic from January 1998 until December 2001. Controls were all men with normozoospermia attending our fertility clinic in the same period. Family data were collected from the medical records and by additional interviews of the probands. If subfertility of a first-degree relative was mentioned, permission was sought to contact the affected family member in order to obtain all medical information available, including the results of semen analyses. RESULTS: In total, 160 patients and 285 controls were included in the analysis. Family size and number of brothers and sisters were equally distributed in both groups. In the patient group, 1.63% of the brothers who had tried to father a child were mentioned to be subfertile compared to 5.8% in the control group [odds ratio 3.18 (95% confidence interval 1.59-6.37)]. The subfertility among the brothers in the patient group was more often due to reduced semen parameters compared to the control group. The data did not fit with frequent autosomal dominant or recessive segregation. CONCLUSION: Male factor subfertility due to impaired spermatogenesis appears to cluster in families. Our data suggests that heritable genetic factors play a role in a limited number of cases. Impaired spermatogenesis is not caused by a common genetic defect, but is most likely a complex disease in which several different factors play a role.

Adult↗

Inheritance patterns of transcript levels in F1 hybrid mice.

Genetic analysis of transcriptional regulation is a rapidly emerging field of investigation that promises to shed light on the regulatory networks that control gene expression. Although a number of such studies have been carried out, the nature and extent of the heritability of gene expression traits have not been well established. We describe the inheritance of transcript levels in liver tissue in the first filial (F1) generation of mice obtained from reciprocal crosses between the common inbred strains A/J and C57BL/6J. We obtain estimates of genetic and technical variance components from these data and demonstrate that shrinkage estimators can increase detectable heritability. Estimates of heritability vary widely from transcript to transcript, with one-third of transcripts showing essentially no heritability (<0.01) and one-quarter showing very high heritability (>0.50). Roughly half of all transcripts are differentially expressed between the two parental strains. Most transcripts show an additive pattern of inheritance. Dominance effects were observed for 20% of transcripts and a small number of transcripts were identified as showing an overdominance mode of inheritance. In addition, we identified 314 transcripts with expression levels that differ between the reciprocal F1 animals. These genes may be related to maternal effect.

Animals↗

Genetics beyond Mendel. Understanding nontraditional inheritance patterns.

Many medical conditions that clearly have a strong genetic component are not transmitted in a straightforward dominant, recessive, or X-linked pattern. Recent progress in understanding other modes of inheritance, such as imprinting, trinucleotide repeat expansion, mitochondrial inheritance, and mosaicism, has allowed us to solve many of these hereditary puzzles. Such advances have led to improvements in diagnosis and genetic counseling for patients affected with these disorders and should be valuable in development of effective therapies for some of these disorders in the future.

Angelman Syndrome↗

Mitochondrial inheritance patterns in Didymium iridis are not influenced by stage of mating competency.

To test whether the timing of transition to mating competency affected mitochondrial transmission patterns in D. iridis. Reciprocal crosses were made by combining mating compatible strains that differed in their competency to mate. The results were compared to crosses where both mating strains were competent at the time of combining and crosses where somatic fusion of plasmodia was allowed. The results show that the mating competency of the parental strains at the time of confronting a compatible mate does not affect mitochondrial transmission patterns, mating efficiency or the likelihood of biparental inheritance. However the timing of plasmodial formation is delayed when precompetent and competent strains are mated compared to when both strains are competent at the time of mixing. We also observed that somatic fusion of plasmodia did not appreciably increase the incidence of biparental inheritance compared to crosses where individual plasmodia were isolated. These results provide additional evidence of the variable nature of mitochondrial inheritance in D. iridis within crosses and between mating trials.

Animals↗

Genetic determinants of acute hypoxic ventilation: patterns of inheritance in mice.

Acutely lowering ambient O(2) tension increases ventilation in many mammalian species, including humans and mice. Inheritance patterns among kinships and between mouse strains suggest that a robust genetic influence determines individual hypoxic ventilatory responses (HVR). Here, we tested specific genetic hypotheses to describe the inheritance patterns of HVR phenotypes among two inbred mouse strains and their segregant and nonsegregant progeny. Using whole body plethysmography, we assessed the magnitude and pattern of ventilation in C3H/HeJ (C3) and C57BL/6J (B6) progenitor strains at baseline and during acute (3-5 min) hypoxic [mild hypercapnic hypoxia, inspired O(2) fraction (FI(O(2))) = 0.10] and normoxic (mild hypercapnic normoxia, FI(O(2)) = 0.21) inspirate challenges in mild hypercapnia (inspired CO(2) fraction = 0.03). First- and second-filial generations and two backcross progeny were also studied to assess response distributions of HVR phenotypes relative to the parental strains. Although the minute ventilation (VE) during hypoxia was comparable between the parental strains, breathing frequency (f) and tidal volume were significantly different; C3 mice demonstrated a slow, deep HVR relative to a rapid, shallow phenotype of B6 mice. The HVR profile in B6C3F(1)/J mice suggested that this offspring class represented a third phenotype, distinguishable from the parental strains. The distribution of HVR among backcross and intercross offspring suggested that the inheritance patterns for f and VE during mild hypercapnic hypoxia are consistent with models that incorporate two genetic determinants. These results further suggest that the quantitative genetic expression of alleles derived from C3 and B6 parental strains interact to significantly attenuate individual HVR in the first- and second-filial generations. In conclusion, the genetic control of HVR in this model was shown to exhibit a relatively simple genetic basis in terms of respiratory timing characteristics.

Acute Disease↗

Genetico-mathematical analysis of the inheritance pattern of peptic ulcer disease. Direct methods of Weinberg. I. Method of probands and method of siblings.

Inheritance of ulcer disease was analyzed genetico-mathematically using two methods: the method of probands and the method of siblings. Families of 351 probands were enrolled in the study: 57 had type II and 27 type III gastric ulcer disease. 267 were with duodenal ulcer disease. The types of gastric ulcer were determined according to H. Johnson. A further 188 families of type I gastric ulcer probands were also studied. However, data from these are not included in the present study because our previous investigation has shown no genetic determination of this type of ulcer disease. The detailed segregation analysis employed in the study does not support the assumption of a monogenic type of disease inheritance. The values obtained for the coefficient of genetic proportion do not substantiate either autosomal-recessive or autosomal-dominant pattern of transmission. This refers both to ulcer disease in general and to the calculation of the coefficient depending on the type of disease and the type of familial predisposition of probands.

Bulgaria↗

Spatial inheritance patterns across maize ears are associated with alleles that reduce pollen fitness.

Often, more pollen grains land on recipient flowers than there are ovules to fertilize. Consequently, the haploid male gametophyte engages in post-pollination competition, one way that pollen genotype can influence inheritance. The maize (Zea mays subsp. mays L.) inflorescence (ear), with its elongated stigma and style structures (silks), has a conspicuous spatial heterogeneity, with longer silks at the base of the ear than at the apex. To evaluate the hypothesis that alleles with reduced pollen fitness influence the spatial distribution of progeny genotypes along the ear, we developed an updated phenotyping platform that maps fluorescently marked mutant (Ds-GFP) kernel phenotypes on the ear via an implementation of the Faster R-CNN machine vision model (EarVision.v2) and a statistical pipeline that evaluates the relationship between kernel position and transmission ratio (EarScape). Our dataset (1384 ears) represents 58 Ds-GFP insertion alleles. None of the 48 alleles with Mendelian inheritance showed any significant spatial trend. In contrast, 50% of alleles with a pollen-specific transmission defect (5/10) exhibited significant spatial effects. An insertional mutant of the gene encoding a putative actin-binding protein, base-to-apex gradient1* (bag1*), is associated with decreased mutant transmission at the ear base relative to the apex. Surprisingly, a mutant allele of another pollen-expressed gene (Zm00001eb236740) generates the opposite trend, decreased mutant transmission toward the ear apex; and two mutant alleles of the sperm cell attachment factor gamete expressed2 (gex2) can produce ears with transmission highest at both base and apex. We conclude that pollen fitness mutants cause unexpectedly diverse spatial patterns of progeny genotypes.

Zea mays↗

A study of the inheritance pattern of Romano-Ward syndrome. Prolonged Q-T interval, syncope, and sudden death.

Romano-Ward syndrome consists of attacks of syncope, possible sudden death, accompanied by prolonged Q-T interval on ECG. We carried out HLA antigen typing of a family of 16 members having ten cases of Romano-Ward syndrome. All the ten cases had the common HLA haplotype of A9-Bw54, while the six not showing the symptoms did not have A9-Bw54 haplotype. The genes of this syndrome, considered to be inherited through the autosomal dominant patterns, are assumed to have a close linking to the major histocompatibility complex on the short arm of chromosome number 6.

Adult↗

Aglossia-adactylia syndrome (special emphasis on the inheritance pattern).

Three cases, one with aglossia-adactylia and two with aglossia, are presented, all of whom were born to consanguineous families. Although none of the cases had similarly affected sibs, the possibility of the autosomal recessive mode of inheritance might be taken into account in this syndrome. The dermatoglyphic findings in one previously reported patient showed great similarity to those of one of our cases.

Abnormalities, Multiple↗

Inheritance patterns in recurrent aphthous ulcers: twin and pedigree data.

Nineteen sets of twins and 318 individuals from six families were examined and interviewed in order to ascertain whether a genetic component could be established for recurrent aphthous ulcers (RAU). While no specific mode of inheritance could be established, the data strongly support the hypothesis of a genetic factor involved in susceptibility to the disease.

Diseases in Twins↗

Isolated maxillary bending in CL/FR strain mice: observation of craniofacial deformity and inheritance pattern.

OBJECTIVE: The CL/Fr mouse, known as a strain with spontaneous cleft lip and/or palate (CL/P), has been used as an animal model to investigate etiology in CL/P. METHOD: We examined a facial asymmetry mutant discovered in a CL/Fr mouse colony that was not associated with CL/P and was shown to be inheritable in subsequent generations. Facial asymmetry became apparent with postnatal growth, whereas it was not detectable at birth, and was termed "maxillary bending" (MB) based on the characteristic bending of the maxilla. RESULTS: As a result of selective breeding, an 'MB line', In which MB was observed in 21.68% (67/309) in addition to CL/P in 17.80% (55/309) of the offspring, was developed in the CL/Fr colony. In mating experiments between the MB line and C57BL/6J, all F1 progeny showed the normal phenotype. MB was observed in 0.72% (1/139) of the F2 generation, and the backcross generation showed segregation of MB in 6.25% (22/352) and CL/P in 1.42% (5/352). These instances suggested the occurrence of an additional mutation in the CL/Fr mouse genome controlled by an autosomal recessive gene with low penetrance. However, since the CL/Fr mouse primarily has a developmental deficiency in the maxilla, the possibility that CL/P and MB share common etiologic factors cannot be completely ruled out. CONCLUSION: The maxillary bending retains significance, as this mutant can serve as an animal model of abnormal facial growth. Elucidation of the etiologic relationship between MB and CL/P may provide clues to clarifying the deficiency in first branchial arch in the mouse.

Animals↗

Pattern of inheritance in hereditary myeloperoxidase deficiency associated with the R569W missense mutation.

Myeloperoxidase (MPO) is an essential component of the oxygen-dependent microbicidal system of neutrophils and monocytes. Hereditary deficiency of MPO occurs in 1 in 2,000 to 4,000 individuals in the general population and has been generally considered an autosomal recessive trait. Previous studies have used the peroxidase activity of blood leukocytes to assess the phenotype of affected family members. Eosinophil peroxidase (EPO) also contributes to the peroxidase activity of blood leukocytes. Because EPO expression is normal in MPO-deficient subjects, eosinophil contamination can significantly contribute to peroxidase activity in leukocytes from family members of an MPO-deficient subject and thereby undermine correct interpretation of the inheritance pattern. To avoid this potential problem, we used cytochemical, immunochemical, and genetic techniques to assess the inheritance pattern of MPO deficiency in sixteen individuals from five unrelated kindreds. Each kindred had an index case with MPO deficiency and the R569W missense mutation, a genotype that causes MPO deficiency. Our analysis demonstrated that MPO deficiency was not inherited as a simple autosomal recessive trait. Most subjects were compound heterozygotes with respect to the R569W mutation and demonstrated a spectrum of phenotypes. Our data demonstrate the broad phenotypic impact of compound heterozygosity on the expression and function of a multimeric protein such as MPO.

Female↗

A c-myc gene variant without exon 1 and with an abnormal methylation pattern inherited in a woman with no evidence of malignancy.

A c-myc DNA with a deletion which includes 5' flanking, exon 1 and intron I sequences has been found in normal white blood cells of a mother and one daughter in a Northern Italian family. In addition, the degree of methylation of specific CCGG sites in the truncated DNA is lower in both mother and daughter than that found in normal DNA. It is of interest that deletions of the first exon and hypomethylation of the c-myc gene have usually been observed only in some neoplasias. However, our results demonstrate that the c-myc truncated DNA with the abnormal methylation pattern here reported is a genomic variant which by itself is not related to neoplastic transformation.

Chromosome Deletion↗

The immune response to hepatitis B vaccine in humans: inheritance patterns in families.

We have recently shown that the human antibody response to the hepatitis B virus surface antigen (HBsAg) vaccine is major histocompatibility complex (MHC) associated. In studies of nonresponders to the vaccine, we found an increased incidence of individuals homozygous for human histocompatibility leukocyte antigen (HLA) proteins associated with the extended (conserved) haplotype [HLA-B8,SC01,DR3]. In later prospective vaccination trials, we showed that none of five individuals homozygous for this haplotype developed more than 1,300 radioimmunoassay (RIA) units of antibody (mean, 467 RIA units), while all heterozygotes made at least 2,500 RIA units (mean antibody level, 15,608 units). Our results suggested that [HLA-B8,SC01,DR3] lacks an immune response gene for HBsAg, and that response is inherited in a dominant fashion. To provide further evidence for this hypothesis, we have now analyzed the results of HBsAg immunization in families. 43 members of 10 families were immunized with the hepatitis B vaccine, including seven families where at least one member bore the haplotype [HLA-B8,SC01,DR3], and three families where one member had already received, but failed to respond to, the vaccine. In two of these three families, the presence of [HLA-B8,SC01,DR3] was subsequently found. Of nine MHC-identical sibling pairs in the study, both members of eight pairs had similar antibody responses (five nonresponder and three responder pairs). In all families with such sibling pairs, including the discordant pair, rank-ordering members by antibody level demonstrated that no relative's value came between the sibling pair values. Furthermore, of nine [HLA-B8,SC01,DR3]-haplotype-homozygous individuals, six were nonresponders, and two others had only low-normal responses. [HLA-B8,SC01,DR3]-heterozygous family members always had higher levels of antibody than their homozygous relatives. Linkage analysis of nonresponse to HLA haplotypes revealed a maximum likelihood LOD (logarithm of the odds) score of 6.3 at a recombination fraction of 0.1. The MHC association with lack of antibody response to HBsAg was not seen with tetanus immunization, where 1 of 20 HBsAg responders and 1 of 21 poor or nonresponders had tetanus titers of less than 1:512; both tetanus nonresponders were [HLA-B8,SC01,DR3] heterozygotes. Our results indicate that: (a) response to the HBsAg vaccine is MHC linked, and inherited in a dominant fashion; (b) an abnormal or missing immune response (Ir) gene for HBsAg is a characteristic of most examples of the extended haplotype [HLA-B8,SC01,DR3]; and (c) other haplotypes also have abnormal or missing Ir genes for HBsAg.

Female↗

Inheritance pattern of mutant human immunodeficiency virus type 1 coreceptor gene CCR5 in an Indian family.

The most common form of mutation found in the CCR5 gene has been the precise 32-base pair (bp) deletion in the region corresponding to second extracellular loop of the chemokine receptor CCR5. Individuals homozygous for the delta 32 allele of CCR5 usually remain uninfected despite multiple exposures to HIV, whereas heterozygous individuals support less virus replication and show slower progression of the disease. This mutant allele in either homozygous or heterozygous form is quite common in white people of European heritage. Earlier work involving large populations of Asians and Africans failed to detect the presence of this mutant allele. We screened 145 normal unrelated healthy Indians and found one person who was heterozygous for the delta 32 allele of CCR5. We studied the inheritance of this deleted allele in this person's family. One parent, one of two sons, and the only daughter possessed this mutant allele. We cloned the entire coding region of wild-type and mutant alleles of CCR5 gene from the heterozygous individual mentioned and studied its coreceptor functions. The mutant allele had only a moderate interfering effect on coreceptor activity of the wild-type CCR5 allele in a cell fusion assay. We also report an improved method of genotyping CCR5 gene in this communication.

Alleles↗

Two families with an autosomal dominant inheritance pattern for papillary carcinoma of the thyroid.

BACKGROUND: Papillary carcinoma of the thyroid (PTC) is the most prevalent malignancy of the thyroid gland. Although the majority of lesions are sporadic tumors, an established relationship exists between familial adenomatous polyposis (FAP) and PTC. Moreover, some authors postulate the existence of familial PTC as a distinct entity. Evidence for this is limited, however, there being few well characterized descriptions of pedigrees with high prevalence of PTC. AIMS: The objective of the present study was to examine an apparent heritable predisposition to PTC occurring in two Tasmanian families in which PTC occurs commonly. METHODS: Pedigree charts were constructed for both families and the medical records of the members reviewed. RESULTS: In Pedigree I, 7 of 25 members had PTC (6 of these had coexisting multinodular goiter (MNG), and 11 others had MNG. In Pedigree II, identical male twins and their daughters had PTC. CONCLUSIONS: In both families there is evidence of autosomal dominant inheritance of PTC. The association of PTC with MNG suggests a possible role for MNG in tumor pathogenesis in hereditary PTC. The majority of the patients were diagnosed with PTC before commencement of prospective screening, indicating clinically relevant disease in the families described.

Adult↗

Malathion resistance in Tribolium strains and their hybrids: inheritance patterns and possible enzymatic mechanisms (Coleoptera, Tenebrionidae).

(1) The genetics of malathion resistance in two strains of the flour beetle, Tribolium castaneum, was investigated. In CTC-12, resistance is polygenic, while in Kano, it is due to a dominant allele at a single autosomal locus. Reciprocal hybrids with the susceptible control strains bb and pp showed an overdominant response in particular when Kano was the male parent in the original cross. (2) Three possible genetic mechanisms to explain these results are discussed. The model which best explains the genetic results, particularly the difference between the reciprocal crosses, assumes a modifier resistance allele on the Y chromosome. (3) The levels of activity of total esterases, carboxylesterases, mixed-function oxidases, epoxide hydrase, and glutathione transferase in the parent strains and their hybrids were measured quantitatively. Although total esterase activity may not be relevant for the breakdown of malathion, it was inhibited by the pesticide. The activity of the microsomal enzymes was high in CTC-12, low in bb, and intermediate in the hybrids, while carboxylesterases were very active in Kano as well as in the hybrids with bb and low in the latter. These patterns agree with the genetics of resistance in the two strains. A higher level of GSH transferase in the Kano x bb hybrids than in Kano seems to indicate a possible biochemical mechanism for their overdominant resistance.

Animals↗

Inheritance patterns of maternal alleles in imprinted regions of the mouse genome at different stages of development.

Deviations from Mendelian 1:1 transmission ratio have been observed in mice and humans. With few exceptions, the mechanism leading to transmission-ratio distortion (TRD) remains obscure. We proposed that a genomic imprinting mechanism plays a key role in the genesis of grandparental origin-dependent TRD (Naumova et al. 2001). To further test this hypothesis, we analyzed the transmission of grandparental alleles at three imprinted regions of the mouse genome known to contain genes required for embryo development. We found and replicated moderate (58%: 42%) TRD in favor of grandmaternal alleles in the imprinted region of maternal distal Chromosome (Chr) 12 among female offspring. Comparison of transmission ratios at the distorted region of Chr 12 among 3-week-old mice with those in embryos suggests that the distortion in favor of grandmaternal alleles is owing to postimplantation embryo loss. The absence of grandparental origin-dependent TRD for maternal Chr 6 and 7 implies that the relationship between TRD and imprinting is complex. Most likely, multiple conditions are required for TRD to occur.

Alleles↗