Mutations in 3ß-hydroxysteroid-δ8, δ7-isomerase paradoxically benefit epidermal permeability barrier homeostasis in mice.

Inherited or acquired blockade of distal steps in the cholesterol synthetic pathway results in ichthyosis, due to reduced cholesterol production and/or the accumulation of toxic metabolic precursors, while inhibition of epidermal cholesterol synthesis compromises epidermal permeability barrier homeostasis. We showed here that 3ß-hydroxysteroid-δ8, δ7-isomerase-deficient mice (TD), an analog for CHILD syndrome in humans, exhibited not only lower basal transepidermal water loss rates, but also accelerated permeability barrier recovery despite the lower expression levels of mRNA for epidermal differentiation marker-related proteins and lipid synthetic enzymes. Moreover, TD mice displayed low skin surface pH, paralleled by increased expression levels of mRNA for sodium/hydrogen exchanger 1 (NHE1) and increased antimicrobial peptide expression, compared with wild-type (WT) mice, which may compensate for the decreased differentiation and lipid synthesis. Additionally, in comparison with WT controls, TD mice showed a significant reduction in ear thickness following challenges with either phorbol ester or oxazolone. However, TD mice exhibited growth retardation. Together, these results demonstrate that 3ß-hydroxysteroid-δ8, δ7-isomerase deficiency does not compromise epidermal permeability barrier in mice, suggesting that alterations in epidermal function depend on which step of the cholesterol synthetic pathway is interrupted. But whether these findings in mice could be mirrored in humans remains to be determined.

Adult presentation of X-linked Conradi-Hünermann-Happle syndrome.

Conradi-Hünermann-Happle syndrome, or X-linked dominant chondrodysplasia punctata type 2 (CDPX2), is a genodermatosis caused by mutations in EBP. While typically lethal in males, females with CDPX2 generally manifest by infancy or childhood with variable features including congenital ichthyosiform erythroderma, chondrodysplasia punctata, asymmetric shortening of the long bones, and cataracts. We present a 36-year-old female with short stature, rhizomelic and asymmetric limb shortening, severe scoliosis, a sectorial cataract, and no family history of CDPX2. Whole exome sequencing (WES) revealed a p.Arg63del mutation in EBP, and biochemical studies confirmed a diagnosis of CDPX2. Short stature in combination with ichthyosis or alopecia, cataracts, and limb shortening in an adult should prompt consideration of a diagnosis of CDPX2. As in many genetic syndromes, the hallmark features of CDPX2 in pediatric patients are not readily identifiable in adults. This demonstrates the utility of WES as a diagnostic tool in the evaluation of adults with genetic disorders.

[Conradi-Hünermann-Happle syndrome with unilateral distribution]. / Syndrome de Conradi-Hünermann-Happle de disposition unilatérale.

BACKGROUND: X-linked dominant chondrodysplasia punctata, also known as Conradi-Hünermann-Happle syndrome or CDPX2, is a rare type of genodermatosis with heterogeneous clinical phenotypes. It is characterized by the association of usually bilateral and symmetrical Blaschko-linear cutaneous lesions, ocular involvement, morphological, and skeletal abnormalities (characteristic punctuate epiphyseal calcifications). CASE REPORT: A female newborn was examined for a squamous glazed erythema mainly located on the left half of the body. Standard X-rays of the left wrist showed punctuate epiphyseal calcifications. The diagnosis was confirmed by molecular studies, which revealed a mutation on the gene encoding the 3beta-hydroxy-steroid-Delta(8), Delta(7)-isomerase. DISCUSSION: We report the case of a baby girl with mainly unilateral skin lesions of CDPX2, possibly due to mosaicism associated with X-inactivation. A diagnosis of CDPX2 must be considered in the event of a female newborn with ichthyosiform Blaschko-linear cutaneous lesions of atypical topography.

X-Linked dominant chondrodysplasia punctata: prenatal diagnosis and autopsy findings.

OBJECTIVE: To report our experience of the prenatal diagnosis of X-linked dominant chondrodysplasia punctata (CDPX2) and highlight its variable phenotypic presentation. METHODS: We report the sonographic features of three female fetuses affected with CDPX2. The ultrasound, radiographic and pathological findings were compared. RESULTS: Family 1: Two affected pregnancies, both terminated. Fetus 1: Presented with epiphyseal stippling involving the vertebrae, upper and lower limbs, asymmetric shortening of the long bones and flat facial profile. Fetus 2: Prenatal findings included premature epiphyseal stippling, paravertebral cartilaginous calcific foci, mild shortening of the long bones and flat facies. Mutation analysis of the mother and both fetuses revealed mutation in the emopamil-binding protein (EBP) gene. Family 2: Prenatal sonography showed scattered epiphyseal stippling, minimal vertebral segmentation anomalies, mild asymmetric limb shortening and flat facies. Female infant delivered at 39 weeks of gestation. Biochemical analysis in all three fetuses showed increased levels of serum 8(9)-cholestenol consistent with delta (8), delta (7)-isomerase deficiency and CDPX2. CONCLUSION: Prenatal diagnosis of CDPX2 is difficult because of marked phenotypic variation. Epiphyseal stippling, ectopic paravertebral calcifications, asymmetric shortening of long bones and dysmorphic flattened facies are crucial for prenatal diagnosis. DNA analysis of the CDPX2 gene and biochemical determination of the serum 8(9)-cholestenol level are important for diagnosis, especially if future pregnancies are planned.

Molecular biology of the 3beta-hydroxysteroid dehydrogenase/delta5-delta4 isomerase gene family.

The 3beta-hydroxysteroid dehydrogenase/Delta(5)-Delta(4) isomerase (3beta-HSD) isoenzymes are responsible for the oxidation and isomerization of Delta(5)-3beta-hydroxysteroid precursors into Delta(4)-ketosteroids, thus catalyzing an essential step in the formation of all classes of active steroid hormones. In humans, expression of the type I isoenzyme accounts for the 3beta-HSD activity found in placenta and peripheral tissues, whereas the type II 3beta-HSD isoenzyme is predominantly expressed in the adrenal gland, ovary, and testis, and its deficiency is responsible for a rare form of congenital adrenal hyperplasia. Phylogeny analyses of the 3beta-HSD gene family strongly suggest that the need for different 3beta-HSD genes occurred very late in mammals, with subsequent evolution in a similar manner in other lineages. Therefore, to a large extent, the 3beta-HSD gene family should have evolved to facilitate differential patterns of tissue- and cell-specific expression and regulation involving multiple signal transduction pathways, which are activated by several growth factors, steroids, and cytokines. Recent studies indicate that HSD3B2 gene regulation involves the orphan nuclear receptors steroidogenic factor-1 and dosage-sensitive sex reversal adrenal hypoplasia congenita critical region on the X chromosome gene 1 (DAX-1). Other findings suggest a potential regulatory role for STAT5 and STAT6 in transcriptional activation of HSD3B2 promoter. It was shown that epidermal growth factor (EGF) requires intact STAT5; on the other hand IL-4 induces HSD3B1 gene expression, along with IL-13, through STAT 6 activation. However, evidence suggests that multiple signal transduction pathways are involved in IL-4 mediated HSD3B1 gene expression. Indeed, a better understanding of the transcriptional factors responsible for the fine control of 3beta-HSD gene expression may provide insight into mechanisms involved in the functional cooperation between STATs and nuclear receptors as well as their potential interaction with other signaling transduction pathways such as GATA proteins. Finally, the elucidation of the molecular basis of 3beta-HSD deficiency has highlighted the fact that mutations in the HSD3B2 gene can result in a wide spectrum of molecular repercussions, which are associated with the different phenotypic manifestations of classical 3beta-HSD deficiency and also provide valuable information concerning the structure-function relationships of the 3beta-HSD superfamily. Furthermore, several recent studies using type I and type II purified enzymes have elegantly further characterized structure-function relationships responsible for kinetic differences and coenzyme specificity.

Cloning of an emopamil-binding protein (EBP)-like protein that lacks sterol delta8-delta7 isomerase activity.

EBP (emopamil-binding protein) is a high-affinity binding protein for [3H]emopamil and belongs to the family of so-called sigma receptors. Mutations that disrupt EBP's 3beta-hydroxysteroid sterol delta8-delta7 isomerase activity (EC 5.3.3.5) impair cholesterol biosynthesis and cause X-chromosomal dominant chondrodysplasia punctata. We identified a human cDNA for a novel EBPL (EBP-like protein) with a calculated mass of 23.2 kDa. Amino acid sequence alignments and phylogenetic analysis revealed that EBPL is distantly related to EBP (31% identity and 52% similarity) and found in animals but not in plants. EBPL is encoded by four exons on human chromosome 13q14.2 covering 30.7 kb, and a partially processed EBPL pseudogene was found on 16q21. The EBPL mRNA was expressed ubiquitously and most abundant in liver, lung and kidney. Upon heterologous expression in yeast EBPL had no detectable 3beta-hydroxysteroid sterol delta8-delta7 isomerase and sigma-ligand-binding activity. Nine out of ten amino acid residues essential for catalytic activity of EBP were conserved in EBPL. Replacement of the only differing residue (EBP-Y111W) reduced catalytic activity of EBP. Transfer of the divergent residue from EBP to EBPL (EBPL-W91Y) and chimaerization of EBP and EBPL at various positions failed to restore catalytic activity of EBPL. Chemical cross-linking induced homodimerization of EBPL and EBP. Whereas mevinolin increased the mRNA for EBP and DHCR7 (delta7-sterol reductase) in HepG2 cells, it had no effect on mRNAs for EBPL and sigma1 receptor, indicating that EBP and EBPL expression are not co-ordinated. We propose that EBPL has a yet-to-be-discovered function other than cholesterol biosynthesis.

The identification of unusual bile acid metabolites by tandem mass spectrometry: use of low-energy collision-induced dissociation to produce informative spectra.

The use of collision-induced dissociation (CID) tandem mass spectrometry (MS/MS) has been shown to produce fragmentation that is useful for the structural analysis of bile acids and their conjugates. Low-energy CID using a triple quadrupole has been used to help characterise bile acid identity but the majority of work has been conducted using high-energy CID on specialised instrumentation. This paper describes the use of low-energy CID as a rapid method for identification of urinary bile acids and presents some examples of its use in the diagnosis of liver disease in infants. These include the differential diagnosis of peroxisomal disorders, identification of compounds (e.g. 3 beta,7 alpha-dihydroxy-5-cholenoic acid 3-sulphate) indicative of 3 beta-hydroxy-delta 5-C27-steroid dehydrogenase/isomerase deficiency and the confirmation of the identity of an unusual bile acid series consisting of different conjugates of lithocholic acid. The use of lithium cationisation and derivatisation with aminosulfonic acids for the analysis of unconjugated and glycine-conjugated bile acids has also been evaluated.

No evidence of mutations in the genes for type I and type II 3 beta-hydroxysteroid dehydrogenase (3 beta HSD) in nonclassical 3 beta HSD deficiency.

Nonclassical 3 beta-hydroxysteroid dehydrogenase/delta 5-delta 4-isomerase deficiency (NC3 beta HSDD) has been diagnosed in hyperandrogenic women with an increasing frequency during the last 14 yr. Fifteen menarcheal women with androgen excess syndrome, diagnosed with NC3 beta HSDD previously were restudied, in 12 after discontinuation of glucocorticoid treatment, in 2 patients never treated with glucocorticoids, and in 1 both before and after glucocorticoid therapy. Each of the 15 patients underwent ACTH stimulation testing, in some cases on multiple occasions. Although some (very few) patients seem to have improved with time, others remained the same or got worse. Molecular DNA analysis was also performed in 6 of the patients, using the strategy successfully used to detect point mutations in the type II 3 beta-hydroxysteroid dehydrogenase (3 beta HSD) gene, which are responsible for classical 3 beta HSD deficiency. This strategy consists of the direct sequencing of polymerase chain reaction-amplified DNA fragments corresponding to the complete coding sequence and all intron-exon junctions and to the 5'- and 3'-noncoding region of this gene. We were unable to demonstrate any mutation of the type II 3 beta HSD gene in these 6 patients. To gain additional information about potential mutations, direct sequencing of the type I 3 beta HSD gene was also performed using this same strategy, and no mutations were found. The present study strongly suggests that unlike the salt-losing and nonsalt-losing forms of classical 3 beta HSD deficiency, NC3 beta HSDD is not due to a mutant type II 3 beta HSD enzyme. However, the possibility remains of a mutation(s) in the unsequenced regions of the type II 3 beta HSD gene or elsewhere, such as in a gene for modulatory protein, playing a specific role in the expression of the type II 3 beta HSD gene. On the other hand, knowing the multiple hormonal controls to which 3 beta HSD activity is subject, it cannot be excluded that at least in some cases, NC3 beta HSDD may be an acquired defect, the result of endogenous or environmental factors.

A new cause of progressive intrahepatic cholestasis: 3 beta-hydroxy-C27-steroid dehydrogenase/isomerase deficiency.

There have been a few reports of infants with severe neonatal cholestasis related to a defect in primary bile acid synthesis. To assess the importance of such deficiency among children with progressive intrahepatic cholestasis (Byler disease), screening for inborn errors in bile acid synthesis was performed by fast atom bombardment ionization-mass spectrometry of urine samples from 30 affected children. Bile acid analysis revealed a specific fast atom bombardment ionization-mass spectrometry profile for 3 beta-hydroxy-C27 steroid dehydrogenase/isomerase deficiency in five children who had jaundice, hepatosplenomegaly, and fatty stools beginning at ages ranging from 4 to 46 months. None of them had pruritus. Liver function tests showed persistently normal serum gamma-glutamyltransferase activity, low serum cholesterol and vitamin E levels, normal serum bile acid concentrations despite raised serum bilirubin levels, and decreased prothrombin time and clotting factor V. In four of the cases a similar disease was observed in siblings. Liver function returned to normal after oral ursodeoxycholic acid therapy. We conclude that 3 beta-hydroxy-C27-steroid dehydrogenase/isomerase deficiency should be considered when idiopathic cholestatic liver disease with clinical features akin to Byler disease is characterized by the association of normal serum gamma-glutamyltransferase activity, normal serum bile acid concentration, absence of pruritus, and a return to normal liver function during ursodeoxycholic acid therapy. Early identification of these children is essential because they benefit from bile acid therapy and might thus avoid the need for liver transplantation.

Inborn errors of metabolism with consequences for bile acid biosynthesis. A minireview.

Five inborn errors with consequences for bile acid biosynthesis have been described: 7-dehydrocholesterol 7-reductase deficiency, 3 beta-hydroxysteroid delta 5-oxidoreductase/isomerase deficiency, 3-oxo-delta 4-steroid 5 beta-reductase deficiency, sterol 27-hydroxylase deficiency (cerebrotendinous xanthomatosis), and peroxisomal disease(s) with absence of peroxisomes. Diagnosis and treatment of these very rare disorders are discussed. Bile acid therapy is important in most of these disorders and in the case of 3 beta-hydroxysteroid delta 5-oxidoreductase/isomerase deficiency and 3-oxo-delta 4-steroid 5 beta-reductase deficiency such therapy may save the life of the affected cholestatic infant. In the case of sterol 27-hydroxylase deficiency, early treatment with chenodeoxycholic acid may prevent the development of progressive neurological dysfunction, dementia, and ataxia. In the latter three cases early diagnosis and treatment is of utmost importance.

A new inherited variant of the 3 beta-hydroxysteroid dehydrogenase-isomerase deficiency syndrome: evidence for the existence of two isoenzymes.

The clinical and endocrine features of a unique form of adrenal insufficiency secondary to an inherited deficiency of 3 beta-hydroxysteroid dehydrogenase-isomerase (3-HSD) were studied. The propositus was a 19-yr-old man with a history of repeated episodes of acute adrenal crisis. Family study disclosed that a 6-yr-old female sibling also was affected, and a third sibling had died during the course of an adrenal crisis. The diagnosis of adrenal insufficiency was established on the basis of extremely low serum cortisol levels and urinary 17-hydroxycorticosteroid excretion with concomitantly elevated serum ACTH levels and lack of cortisol response to ACTH administration. Impairment of C-21 steroid 3-HSD activity was strongly suggested by persistency elevated serum 17-hydroxypregnenolone to 17-hydroxyprogesterone and pregnenolone to progesterone ratios, their significant increase after ACTH administration, and their return to normal during cortisol therapy in both patients. Nevertheless, the serum dehydroepiandrosterone to androstenedione ratio, both basally and after ACTH and/or hCG stimulation, was normal. These findings coupled with the normal phenotypic development and onset of puberty in the two patients indicated intact C-19 steroid 3-HSD activity. The overall results indicate an inherited impairment of 3-HSD activity confined only to C-21 steroid substrates and, thus, suggest the existence of at least two 3-HSD isoenzymes under independent genetic regulation.

Diseases and tumours associated with virilization: pediatric aspects.

Much light has been shed on the underlying disturbances of virilization syndromes. The clinical aspects remain enormously manifold, and close teamwork between the pediatrician and pediatric surgeon is indispensable. In this chapter, the sources of androgens responsible for virilization and the syndrome of male pseudohermaphroditism are discussed in detail.