A novel genetic locus for low renin hypertension: familial hyperaldosteronism type II maps to chromosome 7 (7p22).

Familial hyperaldosteronism type II (FH-II) is caused by adrenocortical hyperplasia or aldosteronoma or both and is frequently transmitted in an autosomal dominant fashion. Unlike FH type I (FH-I), which results from fusion of the CYP11B1 and CYP11B2 genes, hyperaldosteronism in FH-II is not glucocorticoid remediable. A large family with FH-II was used for a genome wide search and its members were evaluated by measuring the aldosterone:renin ratio. In those with an increased ratio, FH-II was confirmed by fludrocortisone suppression testing. After excluding most of the genome, genetic linkage was identified with a maximum two point lod score of 3.26 at theta=0, between FH-II in this family and the polymorphic markers D7S511, D7S517, and GATA24F03 on chromosome 7, a region that corresponds to cytogenetic band 7p22. This is the first identified locus for FH-II; its molecular elucidation may provide further insight into the aetiology of primary aldosteronism.

Ambulatory blood pressure, microalbuminuria, and autonomic neuropathy in adolescents with type 1 diabetes.

OBJECTIVE: To examine the relationship between 24-h blood pressure (BP) measurements, urinary albumin excretion rates, and autonomic neuropathy (AN) in adolescents with type 1 diabetes. RESEARCH DESIGN AND METHODS: A total of 31 patients with microalbuminuria (MA), 20 patients with intermittent MA (I-MA) and 11 patients with persistent MA (P-MA) were identified from the diabetes clinics at two major Australian tertiary care pediatric hospitals. Two control groups were used; one consisted of 19 age-, sex-, and diabetes duration-matched adolescents with normoalbuminuria (NA), and the other consisted of 46 age- and sex-matched nondiabetic control subjects. A medical history and physical examination were followed by a series of noninvasive tests of cardiovascular and pupillary autonomic function and then by 24-h ambulatory blood pressure monitoring (ABPM). RESULTS: ABPM showed an incremental increase in all BP parameters from nondiabetic control subjects through subjects with NA. A parallel incremental increase in diurnal and nocturnal ambulatory heart rates was also evident. Subjects with MA had significantly reduced pupillary adaptation to darkness compared with nondiabetic subjects and subjects with NA. The above results paralleled an incremental increase in HbAlc levels in adolescents with type 1 diabetes from subjects with NA to subjects with P-MA. CONCLUSIONS: Higher 24-h BP values and evidence of subclinical signs of AN are present before P-MA develops and may have important implications for timing the introduction of treatments designed to prevent or retard the microvascular complications of type 1 diabetes in adolescents.

Anisomastia associated with interstitial duplication of chromosome 16, mental retardation, obesity, dysmorphic facies, and digital anomalies: molecular mapping of a new syndrome by fluorescent in situ hybridization and microsatellites to 16q13 (D16S419-D16S503).

Anisomastia is a common problem among developing adolescent girls. We recently evaluated a 22-yr-old female patient who had severe anisomastia (which had been repaired by surgery), associated with moderate to severe mental retardation, a stocky body habitus with mild obesity, dysmorphic facies (prominent, upslanting palpebral fissures, beaked nose, and a prominent philtrum), webbed neck, low hairline, and severe bilateral clinodactyly of the third, fourth, and fifth fingers with acral (but not large joint) flexion contractures. A peripheral blood high resolution karyotype revealed additional chromosomal material within the long arm of chromosome 16. Densitometric analysis of amplified polymorphic sequence-tagged sites (STS) mapping to 16q suggested that the duplication is defined by the noninvolved markers D16S419 [16q12-cen, 66 centimorgan (cM) from 16p terminus] and D16S421 (16q13-q21, 84.4 cM), encompassing a maximum of 18.4 cM of genetic distance. The STS analysis showed that the duplication was on the maternally derived chromosome 16, resulting in two maternal (and one paternal) copies of that region of chromosome 16. The location was further confirmed by bacterial artificial chromosomes (BACs) that were obtained from a commercially available library, labeled, and used for fluorescence in situ hybridization. The BACs containing STSs D16S408, D16S3137, and D16S3032 (markers that correspond to 16q13) showed two regions of hybridization, indicating that these sites were duplicated, whereas a BAC containing the STS D16S512 (which corresponds to 16q21-q22) revealed one hybridization signal per 16q, indicating that the corresponding region was not involved in the duplication. The distance between the probe signals suggested a tandem duplication. We conclude that even though trisomy 16 is the most common autosomal trisomy in spontaneous abortions, few patients with unbalanced chromosome 16 abnormalities survive to adulthood; in this report we describe one such patient with an interstitial chromosome 16 duplication (at 16q13), who had a specific phenotype associated with abnormal breast size. There are clinical similarities between this patient and patients with other 16q abnormalities, although the breast findings were unique. Molecular cytogenetics, including fluorescence in situ hybridization and densitometric analysis of amplified STSs, provided useful tools for the precise mapping of the syndrome to 16q13, where the gene(s) responsible for this phenotype might be localized.

Adrenocortical-pituitary hybrid tumor causing Cushing's syndrome.

We describe the first case of an adrenocortical-pituitary hybrid tumor causing Cushing's syndrome in a 17-yr-old boy. Adrenal vein sampling confirmed elevated secretion of both cortisol and ACTH precursors from a right adrenal mass, whereas pituitary ACTH levels, as determined by bilateral inferior petrosal sinus samples (IPSS), were unresponsive to CRH and equal to peripheral levels. There was no biochemical or histological evidence for a pheochromocytoma, but, rather, the tumor demonstrated lipid-rich clear cells characteristic of an adrenocortical adenoma. Immunohistochemical analysis revealed ACTH immunoreactivity and synaptophysin proteins in the tumor. Isolation of tumor cells by the novel technique of laser capture microdissection and subsequent RT-PCR showed expression of POMC messenger ribonucleic acid and cytochrome p450 enzyme messenger ribonucleic acid within the same cells. Finally, ultrastructural analysis provided ultimate proof for adrenocortical-pituitary hybrid cells exhibiting the characteristic vesicular mitochondria and abundant smooth endoplasmic reticulum of steroid cells and the typical secretory granules of corticotrophs within the cytoplasm of the same cells. The adrenocortical tumor expressed the pituitary transcription factor pituitary homeobox factor 1 and the steroidogenic factor 1. The intermingling of the centrally located ectodermally derived pituitary tissue with the mesodermally derived adrenocortical tissue in this adenoma suggests a hitherto unrecognized genetic and phenotypic plasticity within the hypothalamic-pituitary-adrenal axis.

Rapid diagnosis of germline p53 mutation using the enzyme mismatch cleavage method.

The p53 tumor suppressor gene is the most commonly altered gene in human cancers. Germline mutations in p53 are the genetic alteration underlying predisposition to multiple cancers in Li-Fraumeni syndrome and Li-Fraumeni-like syndrome. We describe a patient who presented with developed adrenocortical carcinoma at age 19 months and a cerebral primitive neuroectodermal tumor at age 5 years. The patient did not have a family history of cancer. We used the enzyme mismatch cleavage (EMC) method to screen for mutations in the p53 gene and found a germline mutation in exon 7 (codon 248). Loss of heterozygosity analysis in one tumor revealed loss of the wild-type p53 allele. In our report we demonstrate the EMC method to be a rapid and sensitive method for mutation detection.

Thyroid nodules in childhood and adolescence--thirty years of experience.

In the thirty year period between 1966 and 1996, fifty-two patients underwent surgery for thyroid nodules at the Royal Children's Hospital, Melbourne. We aimed to review their presentation, investigation, histology, treatment and to follow up those who had malignant neoplasms. Forty-one of the fifty-two patients presented with a single thyroid nodule. Investigations performed included thyroid function tests (N = 32), thyroid autoantibodies (N = 21), an ultrasound of the thyroid (N = 26) and 99mTechnetium scanning (N = 32). Thirty-five of the neoplasms were benign, the follicular adenoma (N = 16) being the most common. Seventeen patients had malignant neoplasms, seven of whom had papillary and seven of whom had follicular carcinoma. Three patients had medullary carcinoma of the thyroid. Nine of the seventeen patients with thyroid malignancy received post-operative 131I treatment. At the time of this review, all patients were living.

Relative abundance of growth hormone receptor isoforms in rhesus monkey tissues and human transformed lymphocytes.

The growth hormone receptor (GHR) is expressed as one active, full-sequence isoform and one truncated, inactive one that lacks the intracellular signaling domain. The aim of this study was to investigate the variation in the tissue expression of the full and truncated mRNA and protein. Epstein-Barr virus-transformed human B lymphocyte lines were established from 9 normal individuals with a height standard deviation score (SDS) of - 0.1 +/- 1.1 (mean +/- SD). Tissues were also collected from 3 Rhesus monkeys, whose GHR has 94.1 % homology with the human molecule. mRNA quantitation was determined by Real Time Quantitative PCR. Growth hormone receptor expression in transformed lymphocytes was also studied by fluorescence-activated cell sorter analysis. Both isoforms were expressed in transformed lymphocytes, but individual variation in the relative mRNA expression was small (truncated isoform percentage of total receptor mRNA: 17.1 +/- 4.4, mean +/- SD). There was no correlation between donors' height SDS and the expression of either isoform or the ratio between them. Protein expression by FACS analysis showed wider variation among the subjects; however, the relative ratio was similar in all the subjects. In monkey tissues, the truncated receptor showed a tissue-specific distribution. In conclusion, the expression of both isoforms in transformed lymphocytes from normal subjects shows small differences at the RNA or protein levels, and does not correlate with height SDS. Growth hormone splice isoforms show tissue specificity, suggesting local regulation of splicing. Tissues with relatively high expression of the truncated isoform are likely to be more resistant to the effects of GH due to the dominant negative effect of this isoform. In addition, the differential tissue expression might influence the levels of growth hormone binding protein in the immediate milieu of each tissue.

An inherited p53 mutation that contributes in a tissue-specific manner to pediatric adrenal cortical carcinoma.

The incidence of pediatric adrenal cortical carcinoma (ACC) in southern Brazil is 10-15 times higher than that of pediatric ACC worldwide. Because childhood ACC is associated with Li-Fraumeni syndrome, we examined the cancer history and p53 status of 36 Brazilian patients and their families. Remarkably, 35 of 36 patients had an identical germ-line point mutation of p53 encoding an R337H amino acid substitution. Differences within intragenic polymorphic markers demonstrated that at least some mutant alleles arose independently, thus eliminating a founder effect. In tumor cells, the wild-type allele was deleted, and mutant p53 protein accumulated within the nuclei. Although these features are consistent with Li-Fraumeni syndrome-associated adrenal tumors, there was no history of increased cancer incidence among family members. Therefore, this inherited R337H p53 mutation represents a low-penetrance p53 allele that contributes in a tissue-specific manner to the development of pediatric ACC.