Donor splice-site mutations in WT1 are responsible for Frasier syndrome.

Frasier syndrome (FS) is a rare disease defined by male pseudo-hermaphroditism and progressive glomerulopathy. Patients present with normal female external genitalia, streak gonads and XY karyotype and frequently develop gonadoblastoma. Glomerular symptoms consist of childhood proteinuria and nephrotic syndrome, characterized by unspecific focal and segmental glomerular sclerosis, progressing to end-stage renal failure in adolescence or early adulthood. No case of Wilms' tumour has been reported, even in patients with extended follow-up. In contrast with FS patients, most individuals with Denys-Drash syndrome (DDS; refs 6,7) have ambiguous genitalia or a female phenotype, an XY karyotype and dysgenetic gonads. Renal symptoms are characterized by diffuse mesangial sclerosis, usually before the age of one year, and patients frequently develop Wilms' tumour. Mutations of the Wilms'-tumour gene, WT1, cause different pathologies of the urogenital system, including DDS. WT1 is composed of ten exons and encodes a protein with four zinc-finger motifs and transcriptional and tumour-suppressor activities. Alternative splicing generates four isoforms: the fifth exon may or may not be present, and an alternative splice site in intron 9 allows the addition of three amino acids (KTS) between the third and fourth zinc fingers of WT1 (ref. 17). Here we demonstrate that FS is caused by mutations in the donor splice site in intron 9 of WT1, with the predicted loss of the +KTS isoform. Examination of WT1 transcripts indeed showed a diminution of the +KTS/-KTS isoform ratio in patients with FS.

ABCC8 and KCNJ11 molecular spectrum of 109 patients with diazoxide-unresponsive congenital hyperinsulinism.

BACKGROUND: Congenital hyperinsulinism (CHI) is characterised by an over secretion of insulin by the pancreatic ß-cells. This condition is mostly caused by mutations in ABCC8 or KCNJ11 genes encoding the SUR1 and KIR6.2 subunits of the ATP-sensitive potassium (K(ATP)) channel. CHI patients are classified according to their responsiveness to diazoxide and to their histopathological diagnosis (either focal, diffuse or atypical forms). Here, we raise the benefits/limits of the genetic diagnosis in the clinical management of CHI patients. METHODS: ABCC8/KCNJ11 mutational spectrum was established in 109 diazoxide-unresponsive CHI patients for whom an appropriate clinical management is essential to prevent brain damage. Relationships between genotype and radiopathological diagnosis were analysed. RESULTS: ABCC8 or KCNJ11 defects were found in 82% of the CHI cases. All patients with a focal form were associated with a single K(ATP) channel molecular event. In contrast, patients with diffuse forms were genetically more heterogeneous: 47% were associated with recessively inherited mutations, 34% carried a single heterozygous mutation and 19% had no mutation. There appeared to be a predominance of paternally inherited mutations in patients diagnosed with a diffuse form and carrying a sole K(ATP) channel mutation. CONCLUSIONS: The identification of recessively inherited mutations related to severe and diffuse forms of CHI provides an informative genetic diagnosis and allows prenatal diagnosis. In contrast, in patients carrying a single K(ATP) channel mutation, genetic analysis should be confronted with the PET imaging to categorise patients as focal or diffuse forms in order to get the appropriate therapeutic management.

Foxl-2 in gonad development and pathology.

The Foxl-2 gene is involved in eyelid and ovary development. Mutations can lead to a shortened protein and malformations such as BPES associated or not to POF. Forkhead point mutation C134W is a marker of adult type granulosa cell tumors only. Foxl-2 dysregulation is also present in DSD and DSD associated tumors such as Gonadoblastoma and gonadoblastoma like intratubular undetermined germ cell neoplasia. A similar spectrum of pathology involvement is also found for WT1 and RET and gives a new insight into the relationship between development, malformations and oncogenesis.

The inlAB locus mediates the entry of Listeria monocytogenes into hepatocytes in vivo.

The intracellular parasite Listeria monocytogenes is able to induce its internalization by cultured mammalian cells that are not normally phagocytic. This process requires the expression of the chromosomal locus inlAB. We studied the virulence of an inlAB mutant and of its parent in murine listeriosis. Irrespective of the route of inoculation, the inlAB mutant was severely attenuated for growth in the liver. The livers of mice inoculated with the inlAB mutant displayed much smaller infectious foci than the parent as early as 24 h after infection. Electron microscopy showed that these foci consisted of a few inflammatory cells, with few bacteria; bacteria were rarely found within hepatocytes. In contrast, foci in livers of mice inoculated with the parent consisted of islets of heavily infected hepatocytes that were infiltrated by numerous neutrophils; bacteria seemed intact within hepatocytes and damaged within neutrophils. A direct role of inlAB for the entry of L. monocytogenes into hepatocytes was confirmed in a cell infection system using the murine embryonic hepatocyte cell line TIB73. The inlAB mutant was approximately 20-fold less invasive in trans. The "invasion locus" inlAB contributes to protect L. monocytogenes from the host's innate defense mechanisms by promoting its entry into hepatocytes.

Management of Wilms tumors in Drash and Frasier syndromes.

BACKGROUND: Children with WT1 gene-related disorders such as Denys-Drash syndrome (DDS) and Frasier syndrome (FS) are at increased risk of Wilms tumor and end-stage renal disease. We investigated whether Wilms tumors in these patients displayed a specific phenotype or behavior and whether nephron-sparing surgery was beneficial. PROCEDURE: We retrospectively studied all patients with DDS, FS, or other WT1 mutations treated at our institutions between 1980 and 2007. RESULTS: We identified 20 patients, of whom 18 had benign or malignant tumors. Wilms tumors occurred in 15 patients, being unilateral in 10 and bilateral in 5 (20 tumors). Median age at Wilms tumor diagnosis was 9 months. No patients had metastases. According to the International Society of Pediatric Oncology Working Classification, there were 19 intermediate-risk tumors and one high-risk tumor; no tumor was anaplastic. In patients with nephropathy who underwent unilateral nephrectomy for Wilms tumor or nephron-sparing surgery for bilateral Wilms tumor, mean time to dialysis was 11 or 9 months, respectively. Other tumors included three gonadoblastomas (in two patients), one retroperitoneal soft-tissue tumor, and one transitional cell papilloma of the bladder. Two patients, both with stage I Wilms tumor, died from end-stage renal disease-related complications. The median follow-up time for the 18 survivors was 136 months (range, 17-224 months). CONCLUSION: Most Wilms tumors in children with WT1-related disorders were early-stage and intermediate-risk tumors, with a young age at diagnosis. In patients without end-stage renal disease, nephron-sparing surgery should be considered for delaying the onset of renal failure.

Spectrum of HLXB9 gene mutations in Currarino syndrome and genotype-phenotype correlation.

Currarino syndrome (CS) is a rare congenital malformation described in 1981 as the association of three main features: typical sacral malformation (sickle-shaped sacrum or total sacral agenesis below S2), hindgut anomaly, and presacral tumor. In addition to the triad, tethered cord and/or lipoma of the conus are also frequent and must be sought, as they may lead to severe complications if not treated. The HLXB9 gene, located at 7q36, is disease-causing. It encodes the HB9 transcription factor and interacts with DNA through a highly evolutionarily conserved homeodomain early in embryological development. Thus far, 43 different heterozygous mutations have been reported in patients fulfilling CS criteria. Mutation detection rate is about 50%, and reaches 90% in familial cases. Here, we report 23 novel mutations in 26 patients among a series of 50 index cases with CS, and review mutational reports published since the identification of the causative gene. Three cytogenetic anomalies encompassing the HLXB9 gene are described for the first time. Truncating mutations (frameshifts or nonsense mutations) represent 57% of those identified, suggesting that haploinsufficiency is the basis of CS. No obvious genotype-phenotype correlation can be drawn thus far. Genetic heterogeneity is suspected, since at least 19 of the 24 patients without HLXB9 gene mutation harbor subtle phenotypic variations.

Chromosome 11p15 paternal isodisomy in focal forms of neonatal hyperinsulinism.

CONTEXT: Focal forms of congenital hyperinsulinism are due to a constitutional heterozygous mutation of paternal origin in the ABCC8 gene, more often than the KCNJ11 gene, located in the 11p15.1 region. This mutation is associated with the loss of the maternally inherited 11p15.1 to 11p15.5 region in the lesion. We investigated the possible occurrence of a compensatory duplication of the paternal 11p15.1-11p15.5 region. MATERIALS AND METHODS: A combined immunohistochemistry and fluorescent in situ hybridization study on beta-cell interphase nuclei with probes covering two genes located in this region (ABCC8 and CDKN1C genes) was performed in four cases of focal forms of hyperinsulinism. RESULTS: beta-Cells in the lesions of four cases of focal congenital hyperinsulinism were diploid for chromosomes 11 and 13. The 11p15.1 to 11p15.2 and 11p15.4 to 11p15.5 regions containing ABCC8 and CDKN1C genes, respectively, were present with two copies. Loss of the maternal allele was confirmed in these focal lesions with microsatellite markers flanking the ABCC8 and CDKN1C genes, whereas a heterozygous mutation in the ABCC8 gene was inherited from the father. CONCLUSIONS: There is a duplication of the paternal allele on chromosome 11 in the focal forms of hyperinsulinism lesion. The paternal isodisomy observed rendered the beta-cells homozygous for ABCC8 mutation and harbored a K-channel defect in the lesion similar to that observed in diffuse forms of congenital hyperinsulinism.

Transcription factors involved in pancreas development are expressed in paediatric solid pseudopapillary tumours.

AIMS: Solid pseudopapillary tumours (SPT) are rare pancreatic tumours, especially in children. The origin of this benign tumour remains unknown. Mutations of beta-catenin, a gene essential for pancreatic development, are constantly found, leading to delocalization of immunohistochemical signals from the cytoplasm to the nuclei of tumour cells. The aim was to report clinical and histological data of eight children with SPT and explore the immunohistochemical expression of pancreatic duodenal homeobox (PDX) 1 and Sox9, known to be crucial for pancreatic development and linked to the beta-catenin cascade. METHODS AND RESULTS: Eight children with features suggestive of SPT underwent surgical resection. Tumours displayed typical histological appearances. One was incompletely resected and recurred. Immunolabelling revealed nuclear location of beta-catenin in all cases and strong cytoplasmic but no nuclear expression of PDX1 or Sox9 in all but one case. CONCLUSIONS: The clinical behaviour of SPT in the paediatric population is similar to its adult counterpart. Complete surgical resection is essential. PDX1 and Sox9 proteins are exclusively expressed in the cytoplasmic compartment in SPT, suggesting overexpression of the corresponding genes linked to beta-catenin mutations. These findings favour the hypothesis that SPT originates from transformation of normally quiescent pancreatic stem cells.

Airway remodeling is correlated with obstruction in children with severe asthma.

BACKGROUND: Severe asthma may involve an irreversible obstructive pattern, and structural changes in bronchial airways are believed to play a key role in this context. The aim of the present study was to compare airway remodeling in severe asthmatic children with or without obstructive pattern. METHODS: Two groups of children with severe asthma and persistent symptoms, 5-14 years old were included, 15 with persistent obstructive pattern (group O) and 10 without obstructive pattern (group N). Persistent obstructive pattern was defined as a forced expiratory volume in 1 s (FEV(1)) less than 80% of the predicted value after a course of systemic corticosteroids and no significant improvement after bronchodilator. We examined bronchial biopsies by pathological and immunochemical methods and quantified airway smooth muscle (ASM) and mucus gland areas, reticular basement membrane (RBM) thickening, distance between ASM and RBM, muscle light chain kinase (MLCK) expression and number of vessels (CD31 expression). RESULTS: Surface area of ASM (P = 0.009), MLCK expression (P = 0.03) and number of vessels (P = 0.0008) were increased in group O compared with group N. Distance of RBM-ASM was shorter in group O (P = 0.007). FEV(1) negatively correlated with ASM area (r = -0.6; P = 0.002), MLCK expression (r = -0.45; P = 0.02) and CD31 expression (r = -0.7; P = 0.0003), and positively correlated with the distance of RBM-ASM (r = 0.5; P = 0.007). CONCLUSIONS: Structural abnormalities of airway remodeling are present in children with severe asthma. Only an increase in surface area of ASM and the density of the vascular network are more pronounced in children with persistent obstructive pattern, while RBM thickening is similar. These results are concordant with longitudinal studies which emphasize the precocity of bronchial obstruction.

Standardization of a (186)Re sodium perrhenate radiochemical solution using the TDCR method in liquid scintillation counting.

Rhenium-186 has several current and potential applications in nuclear medicine. It decays by beta minus emissions mainly to the fundamental and the 137keV excited levels of (186)Os and by electron capture to (186)W. This paper describes the standardization of this radionuclide using the Triple to Double Coincidence Ratio model (TDCR) method. This is done by the calculation of the energy transferred to the scintillator by considering the various decay/de-excitation paths following the disintegration of the nuclide. The uncertainty on the detection efficiency is evaluated by stochastic methods by considering statistical distribution of theoretical and experimental parameters used in the calculation model. The detection efficiency was found to be higher than 97%, allowing a relative standard uncertainty on the activity determination of about 0.3%.

Rhabdomyosarcoma an ubiquitous pediatric tumour.

Rhabdomyosarcoma is the most common soft tissue tumor in children. It occurs everywhere and its prognosis depends on the location and its histological type--embryonic or alveolar. The new immunohistochemical markers desmin and myogenin in combination with molecular biological detection of specific translocations in alveolar rhabdomyosarcoma improved diagnostic capacities. Less aggressive treatment in curable cases reduces the undesirable outcomes of therapy.

Neonatal hyperinsulinism: clinicopathologic correlation.

Neonatal hyperinsulinism is a life-threatening disease that, when treated by total pancreatectomy, leads to diabetes and pancreatic insufficiency. A more conservative approach is now possible since the separation of the disease into a nonrecurring focal form, which is cured by partial surgery, and a diffuse form, which necessitates total pancreas removal only in cases of medical treatment failure. The pathogenesis of the disease is now divided into K-channel disease (hyperinsulinemic hypoglycemia, familial [HHF] 1 and 2), which can mandate surgery, and other metabolic causes, HHF 3 to 6, which are treated medically in most patients. The diffuse form is inherited as a recessive gene on chromosome 11, whereas most cases of the focal form are caused by a sulfonylurea receptor 1 defect inherited from the father, which is associated with a loss of heterozygosity on the corresponding part of the mother's chromosome 11. The rare bifocal forms result from a maternal loss of heterozygosity specific to each focus. Paternal disomy of chromosome 11 is a rare cause of a condition similar to Beckwith-Wiedemann syndrome. A preoperative PET scan with fluorodihydroxyphenylalanine and perioperative frozen-section confirmation are the types of studies done before surgery when needed. Adult variants of the disease are less well defined at the present time.

Mutations of the RET gene in isolated and syndromic Hirschsprung's disease in human disclose major and modifier alleles at a single locus.

BACKGROUND: In Hirschsprung's disease (HSCR), a hypomorphic allele of a major gene, RET, accounts for most isolated (non-syndromic) cases, along with other autosomal susceptibility loci under a multiplicative model. However, some syndromic forms of HSCR are monogenic entities, for which the disease causing gene is known. OBJECTIVE: To determine whether RET could be considered a modifier gene for the enteric phenotype on the background of a monogenic trait. METHODS: The syndromic HSCR entities studied were congenital central hypoventilation (CCHS) and Mowat-Wilson syndrome (MWS), caused by PHOX2B and ZFHX1B gene mutations, respectively. The RET locus was genotyped in 143 CCHS patients, among whom 44 had HSCR, and in 30 MWS patients, among whom 20 had HSCR. The distribution of alleles, genotypes, and haplotypes was compared within the different groups. To test the interaction in vivo, heterozygous mice were bred for a null allele of Phox2b and Ret genes. RESULTS: RET was shown to act as a modifier gene for the HSCR phenotype in patients with CCHS but not with MWS. The intestine of double heterozygote mice was indistinguishable from their littermates. A loss of over 50% of each gene function seemed necessary in the mouse model for an enteric phenotype to occur. CONCLUSIONS: In CCHS patients, the weak predisposing haplotype of the RET gene can be regarded as a quantitative trait, being a risk factor for the HSCR phenotype, while in MWS, for which the HSCR penetrance is high, the role of the RET predisposing haplotype is not significant. It seems likely that there are both RET dependent and RET independent HSCR cases.

Congenital hyperinsulinism and mosaic abnormalities of the ploidy.

BACKGROUND: Congenital hyperinsulinism and Beckwith-Wiedemann syndrome both lead to beta islet hyperplasia and neonatal hypoglycaemia. They may be related to complex genetic/epigenetic abnormalities of the imprinted 11p15 region. The possibility of common pathophysiological determinants has not been thoroughly investigated. OBJECTIVE: To report abnormalities of the ploidy in two unrelated patients with congenital hyperinsulinism. METHODS: Two patients with severe congenital hyperinsulinism, one overlapping with Beckwith-Wiedemann syndrome, had pancreatic histology, ex vivo potassium channel electrophysiological studies, and mutation detection of the encoding genes. The parental genetic contribution was explored using genome-wide polymorphism, fluorescent in situ hybridisation (FISH), and blood group typing studies. RESULTS: Histological findings diverged from those described in focal congenital hyperinsulinism or Beckwith-Wiedemann syndrome. No potassium channel dysfunction and no mutation of its encoding genes (SUR1, KIR6.2) were detected. In patient 1 with congenital hyperinsulinism and Beckwith-Wiedemann syndrome, paternal isodisomy for the whole haploid set was homogeneous in the pancreatic lesion, and mosaic in the leucocytes and skin fibroblasts (hemihypertrophic segment). Blood group typing confirmed the presence of two erythroid populations (bi-parental v paternal only contribution). Patient 2 had two pancreatic lesions, both revealing triploidy with paternal heterodisomy. Karyotype and FISH analyses done on the fibroblasts and leucocytes of both patients were unremarkable (diploidy). CONCLUSIONS: Diploid (biparental/paternal-only) mosaicism and diploid/triploid mosaicism were present in two distinct patients with congenital hyperinsulinism. These chromosomal abnormalities led to paternal disomy for the whole haploid set in pancreatic lesions (with isodisomy or heterodisomy), thereby extending the range and complexity of the mechanisms underlying congenital hyperinsulinism, associated or not with Beckwith-Wiedemann syndrome.

Quality control of liquid scintillation counters.

Liquid scintillation counting (LSC) is widely used at LNHB for primary standardization of radionuclides (TDCR method), for secondary calibration and also for source stability studies or radioactive purity measurements. A total of five LSC counters are used for these purposes: two locally developed 3-photodetector counters for the implementation of the TDCR method, two Wallac 1414 counters and one Wallac 1220 Quantulus counter. The quality of the LSC measurements relies on the correct operation of these counters and their traceability to the frequency and time units.

[Congenital hyperinsulinism in newborn and infant]. / L'hyperinsulinisme congénital du nouveau-né et du nourrisson.

Congenital hyperinsulinism (HI) is the most important cause of hypoglycaemia in early infancy. The inappropriate oversecretion of insulin is responsible for profound hypoglycaemias requiring aggressive treatment to prevent severe and irreversible brain damage. Several classifications of HI can be attempted, based on: 1) the onset of hypoglycemia in the neonatal period or later in infancy; 2) the histological lesion: focal or diffuse; 3) the genetic transmission: sporadic, recessive, or less frequently dominant. The most common underlying mechanism of HI is dysfunction of the pancreatic ATP-sensitive potassium channel (K(+)(ATP)). The 2 subunits of the K(+)(ATP) channel are encoded by either the sulfonylurea receptor gene (SUR1 or ABCC8) or the inward-rectifying potassium channel gene (KIR6.2. or KCNJ11), both located in the 11p15.1 region. Focal CHI has been shown to result from a paternally inherited mutation on the SUR1 or KIR6.2 gene and loss of the maternal 11p15 allele restricted to the pancreatic lesion. Diffuse HI, frequently due to mutations of the SUR1 or KIR6.2 genes of autosomal recessive inheritance is genetically heterogeneous. The distinction between the focal and the diffuse HI is very important, because the treatments are different. To distinguish between focal and diffuse HI, transhepatic catheterisation with pancreatic venous sampling was the reference technique, but will likely be replaced by [(18)F] Fluoro-L-Dopa PET scan, which is easier to perform. In absence of response to the medical treatment (diazoxide) a limited pancreatectomy permits to cure focal HI, while a diffuse HI requires a subtotal pancreatectomy with high risk of subsequent diabetes mellitus.

Tumoral stroma of salivary pleomorphic adenoma -- histopathological, histochemical and immunohistochemical study.

The aims of our paper were to establish the main histopathological, histochemical and immunohistochemical aspects of tumoral stroma from salivary pleomorphic adenomas. For this purpose we investigated 103 cases by the classical histopathological technique with paraffin embedding and staining with Hematoxylin-Eosin (HE), Hematoxylin-Eosin-Safranin (HES), trichromic Masson, trichromic Goldner Szeckelly, orcein and Periodic Acid Schiff-Blue Alcian (PAS-AA). Immunohistochemically, they were investigated for AE1-AE3, MNF116, CK8, EMA, vimentin, alpha-actin calponin, S-100, GFAP, collagen IV, and PCNA. The results of our study suggest the key role of neoplastic myoepithelial cell in the achievement of diverse morphological aspects of stroma in such neoplasms.

The human SRY protein is present in fetal and adult Sertoli cells and germ cells.

Sex determination in mammals is controlled by the Y chromosome located SRY gene. Despite recent advances towards understanding the mechanisms that regulate sex determination in mammals, the expression profile of the SRY protein in human tissues is unknown. To localize the SRY protein and determine its cellular distribution, we prepared monoclonal antibodies (mAb) against the recombinant SRY protein. One antibody, LSRY1.1, recognizes a SRY-specific epitope and was used to localize the protein in different cells and tissues. The mAb recognizes a protein of 27 kDa in total lysates of HeLa SRYB3 cells. Immunocytochemical staining showed a nuclear localization of the protein. Immunohistochemical studies performed on gonadal tissue of a fetus, a one month-old boy and an adult man, demonstrated the presence of SRY protein in the nucleus of Sertoli and germ cells. In addition two 46,XX SRY(+) males had the SRY protein in their gonadal tissues. All other samples were negative, including all female tissue studied and the testis of a 46,XX SRY(-) male. The presence of SRY protein in fetal and adult gonadal tissues including germ cells suggests that SRY may have other male-specific functions in addition to sex determinism.

Neonatal hyperinsulinemic hypoglycemia: heterogeneity of the syndrome and keys for differential diagnosis.

The two major forms of infantile persistent hyperinsulinemic hypoglycemia require different treatments, but are difficult to differentiate during surgery. Indeed, one is characterized by focal adenomatous hyperplasia often macroscopically invisible, whereas the other consists of a diffuse, but discreet, beta-cell abnormality. We evaluated, in a large series of persistent hyperinsulinemic hypoglycemia, the reliability of two criteria in differentiating these two forms: the mean beta-cell nuclear radius (MNR) and the beta-cell nuclear crowding, i.e. the number of nuclei per 1000 micron 2 beta-cell (BCNC). The values of the largest MNR and of BCNC in cases bearing a focal lesion (respectively, 3.27 microns +/- 0.25 and 14.62 +/- 1.78) were significantly different from those in the diffuse pathology (4.25 microns +/- 0.43 and 10.00 +/- 1.55). Setting the threshold value of MNR at 3.70 microns and that of BCNC at 12.00 enabled correct classification of 90.9% of the diffuse and 100% of the focal forms. beta-Cell nuclear analysis can thus contribute to a subclassification of the syndrome, not allowed by clinical or biological data. If performed during surgery it could help in determining the extent of pancreatectomy necessary to cure the patient, as the diffuse form, with abnormal nuclei in the whole pancreas, requires subtotal to near-total pancreatectomy, whereas the focal form, devoid of abnormal insular beta-cell nuclei, can be cured by partial pancreatectomy.

Evaluation of gonadal function in 107 intersex patients by means of serum antimüllerian hormone measurement.

Fetal male sexual differentiation is driven by two testicular hormones: testosterone (synthesized by interstitial Leydig cells) and antimüllerian hormone (AMH; produced by Sertoli cells present in the seminiferous tubules). Intersex states result either from gonadal dysgenesis, in which both Leydig and Sertoli cell populations are affected, or from impaired secretion or action of either testosterone or AMH. Until now, only Leydig cell function has been assessed in children with ambiguous genitalia, by means of testosterone assay. To determine whether serum AMH would help in the diagnosis of intersex conditions, we assayed serum AMH levels in 107 patients with ambiguous genitalia of various etiologies. In XY patients, AMH was low when the intersex condition was caused by abnormal testicular determination (including pure and partial gonadal dysgenesis) but was normal or elevated in patients with impaired testosterone secretion, whereas serum testosterone was low in both groups. AMH was also elevated during the first year of life and at puberty in intersex states caused by androgen insensitivity. In 46,XX patients with a normal male phenotype or ambiguous genitalia, in whom the diagnosis of female pseudohermaphroditism had been excluded, serum AMH levels higher than 75 pmol/L were indicative of the presence of testicular tissue and correlated with the mass of functional testicular parenchyma. In conclusion, serum AMH determination is a powerful tool to assess Sertoli cell function in children with intersex states, and it helps to distinguish between defects of male sexual differentiation caused by abnormal testicular determination and those resulting from isolated impairment of testosterone secretion or action.