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Olaf Hiort

Publications and source records attributed to Olaf Hiort.

At least 19 recordsLinked to original sources
PubMed2006

[Incomplete androgen insensitivity].

In the androgen insensitivity syndrome (AIS) the androgen effect is decreased in the fetus and the youth despite the adequate testosterone production. Usually the mutation of the androgen receptor is responsible for the disease. In the presented case the external genitalia were similar to female genitalia but masses were palpable in the labioscrotal fold. The karyotype was 46,XY. There was no increase in the testosterone level during the first three months of life. The stimulation test by stanazolol and the androgen receptor gene analysis verified the androgen insensitivity. The mutation was absent in the mother's leukocytes. This fact makes the genetic advising difficult in this family.

Androgen-Insensitivity Syndrome↗
PubMed2006

Cell-line and tissue-specific signatures of androgen receptor-coregulator transcription.

Normal genital skin fibroblasts (GSF) and the human prostate carcinoma cell line LNCaP have been used widely as cell culture models of genital origin to study androgen receptor (AR) signaling. We demonstrate that LNCaP shows a reproducible response to androgens as assessed using cDNA-microarrays representing approximately 32,000 unique human genes, whereas several independent GSF strains are virtually unresponsive. We show that LNCaP cells express markedly higher AR protein levels likely contributing to the observed differences of androgen responsiveness. However, previous data suggested that AR-expression levels alone do not determine androgen responsiveness of human GSF compared to LNCaP. We hypothesized that cell-specific differences in expression levels of AR coregulators might contribute to differences in androgen responsiveness and might be found by comparing LNCaP and GSFs. Using the Canadian McGill-database of AR coregulators ( http://www.mcgill.ca/androgendb ), we identified 61 AR-coregulator genes represented by 282 transcripts on our microarray platform that was used to measure transcript profiles of LNCaP and GSF cells. Baseline expression levels of 48 AR-coregulator transcripts representing 33 distinct genes showed significant differences between GSF and LNCaP, four of which we confirmed by reverse transcriptase polymerase chain reaction. Compared to LNCaP, GSFs displayed significant upregulation of AR coregulators that can function as repressors of AR-transactivation, such as caveolin 1. Analysis of a recently published comprehensive dataset of 115 microarrays representing 35 different human tissues revealed tissue-specific signatures of AR coregulators that segregated with ontogenetically related groups of tissues (e.g., lymphatic system and genital tissues, brain). Our data demonstrate the existence of cell-line and tissue-specific expression patterns of molecules with documented AR coregulatory functions. Therefore, differential expression patterns of AR coregulators could modify tissue-specificity and diversity of androgen actions in development, physiology, and disease.

Androgens↗
PubMed2006

Androgen receptor gene mutations in androgen insensitivity syndrome cause distinct patterns of reduced activation of androgen-responsive promoter constructs.

Assessment of quantitative impairment of reporter gene activation is an important strategy proving pathogenetic relevance of androgen receptor (AR)-gene mutations in androgen insensitivity syndrome (AIS). We hypothesized the additional existence of mutation-specific patterns of reduced target gene activation. Four AR-gene mutations causing AIS, L712F, M780I, R855H, and V866M, respectively, were recreated in an AR-expression plasmid. Activation of three structurally different androgen-dependent promoters (MMTV, (ARE)2TATA, and GRE-OCT) was measured in transfected CHO-cells in response to dihydrotestosterone (DHT), testosterone, androstenedione and stanozolol (S). V866M showed the lowest activity across all conditions. R855H exhibited strikingly high activation of MMTV in response to DHT. M780I showed markedly low activation of (ARE)2TATA by S. L712F demonstrated high activation of GRE-OCT. In essence, each mutation was characterized in this model by a specific pattern of reduced reporter gene activation. Our AR crystal structure analyses showed that L712 and M780 may cause distinct alterations of AR-ligand- and AR-coregulator interaction interfaces supporting the experimental observations. Our data support the hypothesis that mutations of the AR-gene in AIS induce mutation-specific patterns of reduced promoter activation in vitro. Considering the diversity of natural androgen-regulated promoters, mutation-specific differences of androgen response patterns may be of relevance in vivo and consequently may influence the AIS-phenotype. Assessment of transactivation patterns in vitro may be an interesting concept to extend functional description of AR-gene mutations in AIS.

Androgen-Insensitivity Syndrome↗
PubMed2006

Epidemiology and initial management of ambiguous genitalia at birth in Germany.

BACKGROUND: In this epidemiological study, we sought to capture the incidence of ambiguous genitalia in neonates and to describe initial management strategies. METHODS: We used the registry for rare diseases in pediatrics in Germany to ascertain cases and asked reporting institutions for information on phenotype, laboratory tests, imaging results, diagnosis, initial management and sex assignment. RESULTS: We identified 80 cases within a 2-year study period and calculated an incidence of 2 per 10,000 births with ambiguous genitalia per year in Germany. Prevalence was higher in infants from non-German family background. In more than 50% of all infants a definite diagnosis was lacking even at the age of 6 months. In those cases where the etiology was confirmed, the most common diagnosis was congenital adrenal hyperplasia, followed by androgen insensitivity syndrome and mixed gonadal dysgenesis. Associated malformations were very common, affecting 37.5% of all infants. Sex assignment was female in 46,XY infants with predominately female phenotype and all 46,XX infants. Early surgery was performed in many cases irrespective whether a definite diagnosis had been established or not. Integrated psychosocial care was the exception rather than the rule. CONCLUSIONS: Classification and management of ambiguous genitalia at birth remain a challenge for all professionals involved. National and international registries may help to provide a better understanding of the incidence and clinical course of such disorders.

Algorithms↗
PubMed2006

The A645D mutation in the hinge region of the human androgen receptor (AR) gene modulates AR activity, depending on the context of the polymorphic glutamine and glycine repeats.

BACKGROUND: Sufficient androgen receptor (AR) activity is crucial for normal male sexual differentiation. Here we report on two unrelated 46, XY patients suffering from undervirilization and genital malformations. Both patients had a short polyglycine (polyG) repeat of 10 residues and a relatively long polyglutamine (polyQ) repeat of 28 and 30 residues within the transactivation domain of the AR. In addition, they also harbor a rare A645D substitution. OBJECTIVE: We made a set of AR expression plasmid constructs with varying polyQ and polyG tract sizes in context with or without the A645D substitution and analyzed their in vitro transactivation capacity in transfected CHO cells. RESULTS: We found that a short polyG repeat downmodulated AR activity to approximately 60-65% of the wild-type receptor. This effect was aggravated by A645D in context of a long polyQ repeat to less than 50% activity. In contrast, in the context of a short polyQ and a short polyG repeat, the A645D mutation rescues AR activity to almost wild-type levels, demonstrating a contradictory effect of this mutation, depending on the size of the polymorphic repeats. CONCLUSIONS: A combination of a short polyG repeat with a long polyQ repeat and an A645D substitution might contribute to the development of virilization disorders and explain the observed phenotypes of our patients as a form of androgen insensitivity. The whole recreation of AR sequence variations including individual polymorphic repeat sizes could unravel possible interference of mutations and variations on AR activity by in vitro transfection.

Androgen-Insensitivity Syndrome↗
PubMed2006

"Any decision is better than none" decision-making about sex of rearing for siblings with 17beta-hydroxysteroid-dehydrogenase-3 deficiency.

Children with 17beta-hydroxysteroid-dehydrogenase-3 (17beta-HSD-3) deficiency have a defect of testosterone biosynthesis with subsequent diminished virilization in XY individuals. Some are raised as girls and some as boys. There were two purposes of this case report: First, it analyzed the process of decision-making in a family with a pair of siblings with identical mutations leading to 17beta-HSD-3 deficiency whose parents chose to raise one child as a boy and one as a girl. This analysis was based on narrative interviews with the parents. Second, we assessed the gender role behavior and gender identity in the children to examine if the psychosexual development of these children correspond with the sex of rearing their parents chose. When participating in the study, the children were 7 (boy) and 5 (girl) years old. Parents described a difficult process of decision-making and voiced concerns about lack of appropriate and understandable information, and anticipated decision regret. However, they did not feel that the decision to "normalize" the external genitalia should have been deferred. Both children appeared to show age-typical gender-related behavior and did not show any signs of physical or mental distress.

17-Hydroxysteroid Dehydrogenases↗
PubMed2006

17beta-hydroxysteroid dehydrogenase-3 deficiency: a rare endocrine cause of male-to-female sex reversal.

Deficiency of 17beta-hydroxysteroid dehydrogenase type 3 (17beta-HSD3), due to mutations in the gene encoding the enzyme, results in a rare autosomal recessive form of male-to-female sex reversal. Mutated genes encode an abnormal enzyme with absent or reduced ability to convert Delta4-androstenedione to testosterone in the testis. Affected individuals are genetically males who developed internal male Wolffian structures but female external genitalia. Such individuals are usually raised as females and diagnosis is made at puberty, when they show virilization. Correct diagnosis is mandatory to optimize treatment and follow-up. In the present paper we report the clinical history, endocrine evaluation and molecular genetics of a prepubertal girl affected by 17beta-HSD3 deficiency, in whom an erroneous diagnosis of androgen insensitivity syndrome was made. The clinical, endocrine and genetic features of 17beta-HSD3 deficiency are also reviewed.

17-Hydroxysteroid Dehydrogenases↗
PubMed2006

Determination of Gs alpha protein activity in Albright's hereditary osteodystrophy.

Albright's hereditary osteodystrophy (AHO) is a heterogeneous clinical entity in part associated with pseudohypoparathyroidism (PHP) and other endocrinopathies. It may be caused by diminished Gs alpha protein activity. Heterozygous mutations in the underlying GNAS gene on chromosome 20 have been described. One hundred and six patients with suspected AHO, were investigated, of whom 93 showed a laboratory profile of PHP with low or normal calcium and elevated parathormone with normal vitamin D metabolites, and 13 had no endocrine abnormalities. Gs alpha activity was determined in isolated erythrocyte membranes. Molecular genetic analysis of GNAS exons 2-13 was initiated. Significantly reduced Gs alpha activity was found in 91 patients. In 53 patients with reduced Gs alpha activity, a mutation within GNAS was demonstrated. The mutation detection rate was much lower in AHO patients without endocrinopathies than in those who had PHP. In addition, three of the 15 patients with AHO features but normal Gs alpha activity had genetic variations of GNAS. We conclude that determination of Gs alpha activity can be used as a diagnostic screening procedure in patients with suspected AHO. However, the mutation detection rate in GNAS is highly variable. The genetic heterogeneity of AHO needs further investigation.

Adolescent↗
PubMed2005

A novel missense mutation of 5-alpha reductase type 2 gene (SRD5A2) leads to severe male pseudohermaphroditism in a Turkish family.

OBJECTIVES: To analyze the steroid 5-alpha reductase type 2 gene (SRD5A2) in 2 siblings with severe male pseudohermaphroditism suspected to have 5-alpha reductase deficiency in a Turkish family. METHODS: Two female siblings of a family with 7 children were referred to the urology department because of bilateral inguinal masses. The patients had presented after birth with ambiguous genitalia, but no further diagnostic procedures had been performed, and they were raised as girls until the ages of 13 and 15 years. At this time, both had striking ambiguity of the genitalia, with a clitoris-like phallus, severely bifid scrotum, pseudovaginal perineoscrotal hypospadias, a rudimentary prostate, and inguinal testes. Karyotype was 46,XY. Basal and stimulated levels of serum testosterone (T), dihydrotestosterone (DHT), and T/DHT ratio indicated 5-alpha reductase deficiency. Molecular genetic analysis was performed on deoxyribonucleic acid from peripheral blood leukocytes by single-stranded conformational polymorphism analysis and direct sequencing. RESULTS: Analysis of the SRD5A2 gene revealed a new homozygous missense mutation in exon 2. At codon 123, we identified a GGA to AGA change resulting in a missense amino acid change from glycine to arginine (G123R). Both parents and the 2 healthy sisters and 3 brothers were all heterozygous at codon 123 for the same mutation. CONCLUSIONS: We report a novel homozygous missense mutation in exon 2 of the 5-alpha reductase type 2 gene that led to severe undervirilization in 2 siblings.

3-Oxo-5-alpha-Steroid 4-Dehydrogenase↗
PubMed2005

The basis of gender assignment in disorders of somatosexual differentiation.

Sex assignment of patients with disorders of somatosexual differentiation is a controversial topic. The aim is to enable the patient to develop a stable gender identity during childhood, adolescence and adulthood. Enormous advances have recently been made in our knowledge of the molecular mechanisms of sexual differentiation and it is understood that long-term outcome may depend on the underlying diagnosis. There is increasing evidence that genital development is dependent on the action of androgenic steroids; moreover, both androgens and oestrogens may have an impact on other developing organs including neuronal structures such as the brain. Long-term outcome studies on the various intersexuality disorders are desperately needed in order to establish a basis for evidence-based medicine regarding sex assignment and treatment options. Premature decisions leading to irreversible interventions before an accurate diagnosis has been established must be avoided.

Disorders of Sex Development↗
PubMed2005

Early manifestation of calcinosis cutis in pseudohypoparathyroidism type Ia associated with a novel mutation in the GNAS gene.

OBJECTIVE: To clarify the molecular defect for the clinical finding of congenital hypothyroidism combined with the manifestation of calcinosis cutis in infancy. CASE REPORT: The male patient presented with moderately elevated blood thyrotropin levels at neonatal screening combined with slightly decreased plasma thyroxine and tri-iodothyronine concentrations, necessitating thyroid hormone substitution 2 weeks after birth. At the age of 7 months calcinosis cutis was seen and the patient underwent further investigation. Typical features of Albright's hereditary osteodystrophy (AHO), including round face, obesity and delayed psychomotor development, were found. METHODS AND RESULTS: Laboratory investigation revealed a resistance to parathyroid hormone (PTH) with highly elevated PTH levels and a reduction in adenylyl cyclase-stimulating protein (Gsalpha) activity leading to the diagnosis of pseudohypoparathyroidism type Ia (PHP Ia). A novel heterozygous mutation (c364T > G in exon 5, leading to the amino acid substitution Ile-106 --> Ser) was detected in the GNAS gene of the patient. This mutation was not found in the patient's parents, both of whom showed normal Gsalpha protein activity in erythrocytes and no features of AHO. A de novo mutation is therefore likely. CONCLUSIONS: Subcutaneous calcifications in infancy should prompt the clinician to a thorough search for an underlying disease. The possibility of AHO and PHP Ia should be considered in children with hypothyroidism and calcinosis cutis. Systematic reviews regarding the frequency of calcinosis in AHO are warranted.

Calcinosis↗
PubMed2005

Isoenzyme type 1 of 5alpha-reductase is abundantly transcribed in normal human genital skin fibroblasts and may play an important role in masculinization of 5alpha-reductase type 2 deficient males.

OBJECTIVE: 5alpha-reductase enzymes reduce testosterone (T) to the most potent androgen dihydrotestosterone (DHT). Two isoenzymes are known to day. While the type 2-enzyme (5RII) is predominantly expressed in male genital tissues and mutations are known to cause a severe virilization disorder in genetic males, the role of the type 1-enzyme (5RI) in normal male androgen physiology is unclear. We investigated whether 5RI is transcribed in normal male genital skin fibroblasts (GSFs) and if the transcription is regulated by age or by androgens themselves. METHODS: GSF from 14 normally virilized males of different ages, ranging from 8 months to 72 years, obtained at circumcision were cultured. Total RNA was isolated after incubation for 48 h with 100 nM T or without androgens. Each sample was amplified in triplicate by real-time PCR with porphobilinogen desaminase as a housekeeping gene used for semiquantification. Selected cultures were analyzed after incubation with 10 and 100 nM T and 1 and 100 nM DHT for 24, 48 and 120 h. RESULTS: 5RI was transcribed in all investigated samples with a 4.5-fold variability in the mRNA concentration of different individuals. However, neither age-related regulation nor significant influence of T or DHT on the transcription rate was discovered. CONCLUSION: Since 5RI is abundantly transcribed in GSFs, we hypothesize that this isoenzyme may play important roles in the androgen physiology of normally virilized males and may contribute to masculinization in 5RII-deficient males at the time of puberty.

3-Oxo-5-alpha-Steroid 4-Dehydrogenase↗
PubMed2005

Deciding on gender in children with intersex conditions: considerations and controversies.

Biologic factors such as genetic and hormonal influences contribute to gender identity, gender role behavior, and sexual orientation in humans, but this relationship is considerably modified by psychologic, social, and cultural factors. The recognition of biologically determined conditions leading to incongruity of genetically determined sex, somatic phenotype, and gender identity has led to growing interest in gender role development and gender identity in individuals with intersex conditions. Sex assignment of children with ambiguous genitalia remains a difficult decision for the families involved and subject to controversial discussion among professionals and self-help groups. Although systematic empirical data on outcomes of functioning and health-related quality of life are sparse, anecdotal evidence from case series and individual patients about their experiences in healthcare suggests traumatic experiences in some. This article reviews the earlier 'optimal gender policy' as well as the more recent 'full consent policy' and reviews published data on both surgical and psychosocial outcomes. The professional debate on deciding on sex assignment in children with intersex conditions is embedded in a much wider public discourse on gender as a social construction. Given that the empirical basis of our knowledge of the causes, treatment options, long-term outcomes, and patient preferences is insufficient, we suggest preliminary recommendations based on clinical experience, study of the literature, and interviews with affected individuals.

Culture↗
PubMed2004

Homozygous disruption of P450 side-chain cleavage (CYP11A1) is associated with prematurity, complete 46,XY sex reversal, and severe adrenal failure.

Disruption of the P450 side-chain cleavage cytochrome (P450scc) enzyme due to deleterious mutations of the CYP11A1 gene is thought to be incompatible with fetal survival because of impaired progesterone production by the fetoplacental unit. We present a 46,XY patient with a homozygous disruption of CYP11A1. The child was born prematurely with complete sex reversal and severe adrenal insufficiency. Laboratory data showed diminished or absent steroidogenesis in all pathways. Molecular genetic analysis of the CYP11A1 gene revealed a homozygous single nucleotide deletion leading to a premature termination at codon position 288. This mutation will delete highly conserved regions of the P450scc enzyme and thus is predicted to lead to a nonfunctional protein. Both healthy parents were heterozygous for this mutation. Our report demonstrates that severe disruption of P450scc can be compatible with survival in rare instances. Furthermore, defects in this enzyme are inherited in an autosomal-recessive fashion, and heterozygote carriers can be healthy and fertile. The possibility of P450scc-independent pathways of steroid synthesis in addition to the current concept of luteoplacental shift of progesterone synthesis in humans has to be questioned.

Adrenal Insufficiency↗
PubMed2004

Steroid 5alpha-reductase 1 polymorphisms and testosterone/dihydrotestosterone ratio in male patients with hypospadias.

BACKGROUND/AIM: Defects in the steroid 5alpha-reductase type 2 (SRD5A2) activity cause decreased formation of dihydrotestosterone (DHT) from testosterone (T), resulting in defective masculinization of external genitalia; the T/DHT ratio is increased. We investigated 10 patients with elevated T/DHT ratios in whom mutations in the SRD5A2 and AR genes had been excluded to find out whether structural alterations of the SRD5A1 gene could contribute to their genital malformations. METHODS: Single-strand conformation polymorphism analysis and direct sequencing were used to detect variations in the SRD5A1 gene of the patients and of 49 adult fertile men who served as controls. RESULTS: The sequence analysis of exon 3 of the SRD5A1 gene indicated an adenine-to-guanine change (ACA vs. ACG), both triplets encoding the amino acid residue threonine. The ACG sequence was detected in 57% of all subjects and was equally distributed in patients and controls. The T/DHT ratio was significantly higher in controls with the ACG variant as compared with those having the ACA variant. However, no particular sequence aberration was found in the SRD5A1 genes of either group. CONCLUSION: Mutant SRD5A1 isoenzyme does not seem to play a crucial role in the development of hypospadias.

3-Oxo-5-alpha-Steroid 4-Dehydrogenase↗
PubMed2003

Differential gene-expression patterns in genital fibroblasts of normal males and 46,XY females with androgen insensitivity syndrome: evidence for early programming involving the androgen receptor.

BACKGROUND: Androgen insensitivity syndrome (AIS) comprises a range of phenotypes from male infertility to complete feminization. Most individuals with AIS carry germline mutations of the androgen receptor (AR) that interfere with or ablate its function. As genital fibroblasts retain expression of the AR in vitro, we used genital skin fibroblasts from normal males and 46,XY females with complete AIS due to known AR mutations to gain insights into the role of the AR in human genital differentiation. RESULTS: Using DNA microarrays representing 32,968 different genes, we identified 404 transcripts with significant differences in transcription levels between genital skin fibroblasts cultured from normal and AIS-affected individuals. Gene-cluster analyses uncovered coordinated expression of genes involved in key processes of morphogenesis. On the basis of animal studies and human genetic syndromes, several of these genes are known to have specific roles in genital differentiation. Remarkably, genital fibroblasts from both normal and AIS-affected individuals showed no transcriptional response to dihydrotestosterone treatment despite expression of the AR. CONCLUSIONS: The results suggest that in addition to differences in the anatomic origin of the cells, androgen signaling during prenatal development contributes to setting long-lasting, androgen-independent transcriptional programs in genital fibroblasts. Our findings have broad implications in understanding the establishment and the stability of sexual dimorphism in human genital development.

Androgen-Insensitivity Syndrome↗