3,048 research outputs found
Severe combined adrenal and gonadal deficiency caused by novel mutations in the cholesterol side chain cleavage enzyme, P450scc
No full textContext: Mitochondrial cytochrome P450scc converts cholesterol to pregnenolone in all steroidogenic tissues. Although progesterone production from the fetally-derived placenta is necessary to maintain pregnancy to term, four patients with mutations in the gene encoding P450scc (CYP11A1), have been described, one in a 46, XX female and three in underandrogenized 46,XY individuals, all with primary adrenal failure.Objective: Our aim was to determine whether P450scc mutations might be found in other children and to explore genotype/phenotype correlations.Methods and Patients: We performed mutational analysis of CYP11A1 in individuals with 46, XY disorders of sex development and primary adrenal failure, followed by functional studies of P450scc activity and of P450scc RNA splicing.Results: Among nine 46, XY infants with adrenal failure and disordered sexual differentiation, two infants had compound heterozygous mutations in CYP11A1. One patient harbored the novel P450scc missense mutations L141W and V415E, which retained 38 and 0% activity, respectively. The other carried a CYP11A1 frameshift mutation c835delA ( 0% activity) and a splice site mutation [IVS3 +(2-3) insT] that prevented correct splicing of P450scc mRNA.Conclusions: P450scc deficiency is a recently recognized disorder that may be more frequent than originally thought. The phenotypic spectrum ranges from severe loss-of-function mutations associated with prematurity, complete underandrogenization, and severe, early-onset adrenal failure, to partial deficiencies found in children born at term with clitoromegaly and later-onset adrenal failure. In contradistinction to congenital lipoid adrenal hyperplasia caused by steroidogenic acute regulatory protein mutations, adrenal hyperplasia has not been reported in any of the six patients with P450scc deficiency
An alternate translation initiation site circumvents an amino-terminal DAX1 nonsense mutation leading to a mild form of X-linked adrenal hypoplasia congenita
No full textMutations in DAX1 [dosage-sensitive sex reversal-adrenal hypoplasia congenita (AHC) critical region on the X chromosome gene 1; NROB1] cause X-linked AHC, a disease characterized by primary adrenal failure in infancy or childhood and reproductive abnormalities later in life. Most of these patients have nonsense or frameshift mutations that cause premature truncation of the DAX1 protein, thereby eliminating its transcriptional silencing activity. We evaluated a patient with an unusual form of AHC manifest as late-onset adrenal insufficiency and gonadal failure. DNA sequence analysis revealed a novel amino-terminal DAX1 nonsense mutation (Q37X), predicted to cause a severe truncation of the protein. Using a combination of in vitro translation assays and studies of DAX1 expression and function in transfected cells, we demonstrate that, in contrast to more distal mutations leading to a nonfunctional protein, this mutation is associated with a milder phenotype due to the expression of a partially functional, amino-truncated DAX1 protein generated from an alternate in-frame translation start site (methionine, codon 83). The production of this amino-truncated isoform appears to rescue the classical ARC phenotype, thereby delaying the onset of clinically significant adrenal dysfunction until early adulthood. Thus, this case demonstrates a relatively rare phenomenon by which the clinical severity of an inherited human disease is reduced after alternate translation from a site downstream of a premature stop codon
The spectrum of phenotypes associated with mutations in steroidogenic factor 1 (SF-1, NR5A1, Ad4BP) includes severe penoscrotal hypospadias in 46,XY males without adrenal insufficiency
No full textOBJECTIVE. Hypospadias is a frequent congenital anomaly but in most cases an underlying cause is not found. Steroidogenic factor 1 (SF-1, NR5A1, Ad4BP) is a key regulator of human sex development and an increasing number of SF-1 (NR5A1) mutations are reported in 46,XY disorders of sex development (DSD). We hypothesized that NR5A1 mutations could be identified in boys with hypospadias.
DESIGN AND METHODS. Mutational analysis of NR5A1 in 60 individuals with varying degrees of hypospadias from the German DSD network.
RESULTS. Heterozygous NR5A1 mutations were found in three out of 60 cases. These three individuals represented the most severe end of the spectrum studied as they presented with penoscrotal hypospadias, variable androgenization of the phallus and undescended testes (three out of 20 cases (15%) with this phenotype). Testosterone was low in all three patients and inhibin B/anti-Müllerian hormone (AMH) were low in two patients. Two patients had a clear male gender assignment. Gender re-assignment to male occurred in the third case. Two patients harbored heterozygous nonsense mutations (p.Q107X/WT, p.E11X/WT). One patient had a heterozygous splice site mutation in intron 2 (c.103-3A/WT) predicted to disrupt the main DNA-binding motif. Functional studies of the nonsense mutants showed impaired transcriptional activation of an SF-1-responsive promoter (Cyp11a). To date, adrenal insufficiency has not occurred in any of the patients.
CONCLUSIONS. SF-1 (NR5A1) mutations should be considered in 46,XY individuals with severe (penoscrotal) hypospadias, especially if undescended testes, low testosterone, or low inhibin B/AMH levels are present. SF-1 mutations in milder forms of idiopathic hypospadias are unlikely to be common
Clinical, genetic, and functional characterization of four patients carrying partial loss-of-function mutations in the steroidogenic acute regulatory protein (StAR)
No full textContext: Nonclassic congenital lipoid adrenal hyperplasia (lipoid CAH) is a recently recognized disorder caused by mutations in the steroidogenic acute regulatory protein (StAR) that retain partial function. Affected individuals can present with a phenotype of late onset adrenal insufficiency with only mild or minimally disordered sexual development.
Objectives: The aim was to delineate the clinical spectrum of StAR mutations and correlate phenotype with StAR activity.
Patients: Four patients had nonclassic/atypical lipoid CAH. Adrenal insufficiency was manifested at birth in two patients and at 11 months and 4 yr in the other two. Three were 46,XY with underdeveloped genitalia.
Methods: The StAR gene was sequenced, mutations were recreated in expression vectors, and StAR activity was measured as pregnenolone production in COS-1 cells cotransfected with the cholesterol side-chain cleavage system. StAR mutants were expressed as N-62 StAR in bacteria, and purified proteins were tested for activity with isolated steroidogenic mitochondria and for cholesterol-binding capacity.
Results: DNA sequencing identified mutations on all alleles. Missense mutations were R188C, G221D, L260P, and F267S; we also tested R192C described by others. The respective activities of R188C, R192C, G221D, L260P, and F267S were 8.0, 39.4, 2.4, 3.1, and 6.1% of wild-type in transfected cells, and 12.8, 54.8, 6.3, 1.8, and 9.5% with isolated mitochondria. Cholesterol binding capacities of R188C, R192C, G221D, L260P, and F267S were 6.7, 55.3, 10.2, 4.6, and 20.9%. These data are correlated to the three-dimensional structure of StAR.
Conclusions: There is a broad clinical spectrum of StAR mutations; StAR activities in vitro correlate well with clinical phenotypes
Clinical case seminar - Hypogonadotropic hypogonadism as a presenting feature of late-onset X-linked adrenal hypoplasia congenita
No full textMutations in the orphan nuclear receptor DAX-1 cause X-linked adrenal hypoplasia congenita. Affected boys usually present with primary adrenal failure in early infancy or childhood. Impaired sexual development because of hypogonadotropic hypogonadism becomes apparent at the time of puberty. We report adult-onset adrenal hypoplasia congenita in a patient who presented with hypogonadism at 28 yr of age. Although he had no clinical evidence of adrenal dysfunction, compensated primary adrenal failure was diagnosed by biochemical testing. Semen analysis showed azoospermia, and he did not achieve fertility after 8 months of treatment with gonadotropins. A novel Y380D DAX-1 missense mutation, which causes partial loss of function in transient gene expression assays, was found in this patient. This case demonstrates that partial loss-of-function mutations in DAX1 can present with hypogonadotropic hypogonadism and covert adrenal failure in adulthood. Further, an important role for DAX-1 in spermatogenesis in humans is confirmed, supporting findings in the Dax1 (Ahch) knockout mouse
Nonclassic lipoid congenital adrenal hyperplasia masquerading as familial glucocorticoid deficiency
No full textContext: Familial glucocorticoid deficiency (FGD) is an autosomal recessive disorder resulting from resistance to the action of ACTH on the adrenal cortex. Affected individuals are deficient in cortisol and, if untreated, are likely to succumb to hypoglycemia and/or overwhelming infection. Mutations of the ACTH receptor (MC2R) and the melanocortin 2 receptor accessory protein (MRAP), FGD types 1 and 2 respectively, account for approximately 45% of cases.
Objective: A locus on chromosome 8 has previously been linked to the disease in three families, but no underlying gene defect has to date been identified.
Design: The study design comprised single-nucleotide polymorphism genotyping and mutation detection.
Setting: The study was conducted at secondary and tertiary referral centers.
Patients: Eighty probands from families referred for investigation of the genetic cause of FGD participated in the study.
Interventions: There were no interventions.
Results: Analysis by single-nucleotide polymorphism array of the genotype of one individual with FGD previously linked to chromosome 8 revealed a large region of homozygosity encompassing the steroidogenic acute regulatory protein gene, STAR. We identified homozygous STAR mutations in this patient and his affected siblings. Screening of our total FGD patient cohort revealed homozygous STAR mutations in a further nine individuals from four other families.
Conclusions: Mutations in STAR usually cause lipoid congenital adrenal hyperplasia, a disorder characterized by both gonadal and adrenal steroid deficiency. Our results demonstrate that certain mutations in STAR (R192C and the previously reported R188C) can present with a phenotype indistinguishable from that seen in FGD
Human RSPO1/R-spondin1 Is Expressed during Early Ovary Development and Augments beta-Catenin Signaling
No full textHuman testis development starts from around 42 days post conception with a transient wave of SRY expression followed by up-regulation of testis specific genes and a distinct set of morphological, paracrine and endocrine events. Although anatomical changes in the ovary are less marked, a distinct sub-set of ovary specific genes are also expressed during this time. The furin-domain containing peptide R-spondin1 (RSPO1) has recently emerged as an important regulator of ovary development through up-regulation of the WNT/beta-catenin pathway to oppose testis formation. Here, we show that RSPO1 is upregulated in the ovary but not in the testis during critical early stages of gonad development in humans (between 6-9 weeks post conception), whereas the expression of the related genes WNT4 and CTNNB1 (encoding beta catenin) is not significantly different between these tissues. Furthermore, reduced R-spondin1 function in the ovotestis of an individual (46,XX) with a RSPO1 mutation leads to reduced beta-catenin protein and WNT4 mRNA levels, consistent with down regulation of ovarian pathways. Transfection of wildtype RSPO1 cDNA resulted in weak dose-dependent activation of a beta-catenin responsive TOPFLASH reporter (1.8 fold maximum), whereas co-transfection of CTNNB1 (encoding beta-catenin) with RSPO1 resulted in dose-dependent synergistic augmentation of this reporter (approximately 10 fold). Furthermore, R-spondin1 showed strong nuclear localization in several different cell lines. Taken together, these data show that R-spondin1 is upregulated during critical stages of early human ovary development and may function as a tissue-specific amplifier of beta-catenin signaling to oppose testis determination
Progressive onset of adrenal insufficiency and hypogonadism of pituitary origin caused by a complex genetic rearrangement within DAX-1
No full textDAX-1 [dosage-sensitive sex reversal, adrenal hypoplasia congenital (AHC) critical region on the X chromosome, gene 11 is a transcription factor expressed in the adrenal gland and at all levels of the gonadotrope axis. Inactivating mutations of DAX1 result in the X-linked form of AHC with associated hypogonadotropic hypogonadism. AHC usually reveals itself as adrenal failure in early infancy, although a wide range of phenotypic expression has been reported. We describe a patient who was diagnosed with adrenal failure at 6 wk of age, but who experienced recovery of adrenal function of several months' duration later in infancy. He subsequently failed to undergo puberty because of hypogonadotropic hypogonadism of pituitary origin, and he was also diagnosed with schizophrenia in early adulthood. Molecular genetic analyses revealed a complex rearrangement in DAX1, including a 2.2-kb deletion spanning the entire second exon and a small 27-bp insertion. The putative protein encoded by this mutated gene is 429 amino acids long. The initial 389 residues probably correspond to the wild-type DAX-1 sequence, whereas the last 40 amino acids are presumably completely unrelated, being transcribed from the intronic sequence adjacent to exon 1. In vitro functional analyses confirm the absence of repressor activity exerted by such mutant protein. These studies expand the genotypic and phenotypic spectrum of DAX-1 insufficiency in humans
Mutational analysis of DAX1 in patients with hypogonadotropic hypogonadism or pubertal delay
No full textAlthough delayed puberty is relatively common and often familial, its molecular and pathophysiologic basis is poorly understood. In contrast, the molecular mechanisms underlying some forms of hypogonadotropic hypogonadism (HH) are clearer, following the description of mutations in the genes KAL, GNRHR, and PROP1. Mutations in another gene, DAX1 (AHC), cause X-linked adrenal hypoplasia congenita and HH. Affected boys usually present with primary adrenal failure in infancy or childhood and HH at the expected time of puberty.DAX1 mutations have also been reported to occur with a wider spectrum of clinical presentations. These cases include female carriers of DAX1 mutations with marked pubertal delay and a male with incomplete BH and mild adrenal insufficiency in adulthood. Given this emerging phenotypic spectrum of clinical presentation in men and women with DAX1 mutations, we hypothesized that DAX1 might be a candidate gene for mutation in patients with idiopathic sporadic or familial HH or constitutional delay of puberty. Direct sequencing of DAX1 was performed in 106 patients, including 85 (80 men and 5 women) with sporadic HH or constitutional delay of puberty and patients from 21 kindreds with familial forms of these disorders. No DAX1 mutations were found in these groups of patients, although silent single nucleotide polymorphisms were identified (T114C, G498A). This study suggests that mutations in DAX1 are unlikely to be a common cause of HH or pubertal delay in the absence of a concomitant history of adrenal insufficiency
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