Laura Audí

Suppressive therapy with levothyroxine for solitary thyroid nodules

objective To evaluate the effect of treatment with TSH suppressive dose of levothyroxine In patients with benig nthyroid nodules.

Clinical and biochemical determinants of bone metabolism and bone mass in adolescent female patients with anorexia nervosa.

Among pathologies prevalent in western societies, anorexia nervosa has increased over the last decade. Its effects on bone mass need to be defined, and prognostic factors, either clinical or biochemical, could aid clinicians in individual patient management. To determine which clinical and/or biochemical parameters could be related to bone mass status in adolescent female anorexia nervosa patients, 73 female patients were classified according to different stages of their illness and studied in terms of clinical and biochemical parameters and bone densitometric mineral content at lumbar spine. Patients (age 17.2 ± 1.7 y, mean ± SD) with Tanner pubertal stage 5, regular menstruation for more than 3 mo before the onset of secondary amenorrhea, and diagnosed with anorexia nervosa were consecutively studied and classified in three clinical situations:I) active phase (34 patients): undernourished and amenorrheic;II) weight recovered but still amenorrheic (20 patients);III) fully recovered (19 patients). Clinical data were recorded at the time of bone density measurement, concomitant with blood sample extraction for study of IGF-I, IGF-binding protein 3 (IGFBP-3), IGFBP-1, estradiol, sex hormone-binding globulin, dehydroepiandrosterone sulfate, prealbumin, amino-terminal propeptide of procollagen III, osteocalcin, bone alkaline phosphatase, carboxy-terminal propeptide of procollagen I, amino-terminal propeptide of procollagen I, carboxy-terminal telopeptide of collagen I, 25-OH-vitamin D, 1,25(OH)2-vitamin D, and parathormone. In addition, a 24-h urine collection was made for cortisol, GH, deoxypyridinoline, amino-terminal telopeptide of collagen I, and calcium and creatinine content analysis. IGF-I, estradiol, and biochemical bone formation markers were higher and IGFBP-1, sex hormone-binding globulin, and biochemical bone resorption markers were lower in the weight-recovered stages (stages II and III) compared with the active phase (stage I). Bone formation markers correlated positively with body mass index SD score and IGF-I, whereas bone resorption markers correlated negatively with body mass index SD score and estradiol. Although no statistically significant differences regarding lumbar spine bone mineral density SD score values were recorded among the three stages of the illness, the proportion of osteopenic patients was clearly lower among stage III patients. The actual bone mineral density was inversely related to the duration of amenorrhea and directly related to duration of postmenarcheal menses before amenorrhea. In addition, a subset of osteopenic patients (five of 19) in the fully clinically recovered group with accelerated bone turnover was identified. Normal circulating estrogen level exposure time predicts actual bone mineral density at lumbar spine in young adolescent anorexia nervosa patients. In addition to psychiatric and nutritional interventions, estrogen-deprivation periods must be shortened to less than 20 mo. Patients remaining osteopenic at full clinical recovery require additional follow-up studies.

Genetic Determinants of Bone Mass

A genetic contribution to bone mass determination was first described in the early 70s. Elucidation of gene contribution to this has since been attempted through studies analyzing associations between bone mass acquisition and/or maintenance and polymorphic variations of several genes. The first to be described was the vitamin D receptor gene (VDR), initially claimed to contribute to almost 75% of the genetic variation in bone mineral density (BMD) in twin and general population studies. Not all of the studies published to date conclude that a clear relationship exists between polymorphic VDR alleles and BMD, and the molecular basis for the VDR gene polymorphisms influence on bone mineralization has not yet been clarified. Since then, other genes with a significant role in bone metabolism such as estradiol receptor, collagen type 1α1, TGF-β1, interleukin-6, calcitonin receptor, α2-HS-glycoprotein, osteocalcin, calcium-sensing receptor, interleukin-1 receptor antagonist, β3-adrenergic receptor, apolipoprotein E, PTH, IGF-I and glucocorticoid receptor have been analyzed. Some polymorphic variations in these genes have been associated in some works with significant differences in BMD, with even more significant contributions when associations of different gene polymorphisms were analyzed. Again, the molecular basis for the contribution of these alleles to bone mass determination has not yet been described. A different approach has been attempted by linkage analysis of loci involved in bone density in pedigrees with low BMD using BMD as a quantitative trait. Recent results do not confirm, in these families, any association with any of the previously reported genes, but rather with other as yet unidentified genes. The genetic contribution to mild variations in the general population, as a result of environmental and endogenous individual influences, probably differs completely from that providing a pathologic BMD.

Novel (60%) and recurrent (40%) androgen receptor gene mutations in a series of 59 patients with a 46,XY disorder of sex development.

BACKGROUND Androgen receptor (AR) gene mutations are the most frequent cause of 46,XY disorders of sex development (DSD) and are associated with a variety of phenotypes, ranging from phenotypic women [complete androgen insensitivity syndrome (CAIS)] to milder degrees of undervirilization (partial form or PAIS) or men with only infertility (mild form or MAIS). OBJECTIVE The aim of the study was to characterize the contribution of the AR gene to the molecular cause of 46,XY DSD in a series of Spanish patients. SETTING We studied a series of 133 index patients with 46,XY DSD in whom gonads were differentiated as testes, with phenotypes including varying degrees of undervirilization, and in whom the AR gene was the first candidate for a molecular analysis. METHODS The AR gene was sequenced (exons 1 to 8 with intronic flanking regions) in all patients and in family members of 61% of AR-mutated gene patients. RESULTS AR gene mutations were found in 59 individuals (44.4% of index patients), of whom 46 (78%) were CAIS and 13 (22%) PAIS. Fifty-seven different mutations were found: 21.0% located in exon 1, 15.8% in exons 2 and 3, 57.9% in exons 4-8, and 5.3% intronic. Twenty-three mutations (40.4%) had been previously described and 34 (59.6%) were novel. CONCLUSIONS AR gene mutation is the most frequent cause of 46,XY DSD, with a clearly higher frequency in the complete phenotype. Mutations spread along the whole coding sequence, including exon 1. This series shows that 60% of mutations detected during the period 2002-2009 were novel.

Ten Novel Mutations in the NR5A1 Gene Cause Disordered Sex Development in 46,XY and Ovarian Insufficiency in 46,XX Individuals

CONTEXT Steroidogenic factor-1 (SF-1/NR5A1) is a nuclear receptor that regulates adrenal and reproductive development and function. NR5A1 mutations have been detected in 46,XY individuals with disorders of sexual development (DSD) but apparently normal adrenal function and in 46,XX women with normal sexual development yet primary ovarian insufficiency (POI). OBJECTIVE A group of 100 46,XY DSD and two POI was studied for NR5A1 mutations and their impact. DESIGN Clinical, biochemical, histological, genetic, and functional characteristics of the patients with NR5A1 mutations are reported. SETTING Patients were referred from different centers in Spain, Switzerland, and Turkey. Histological and genetic studies were performed in Barcelona, Spain. In vitro studies were performed in Bern, Switzerland. PATIENTS A total of 65 Spanish and 35 Turkish patients with 46,XY DSD and two Swiss 46,XX patients with POI were investigated. MAIN OUTCOME Ten novel heterozygote NR5A1 mutations were detected and characterized (five missense, one nonsense, three frameshift mutations, and one duplication). RESULTS The novel NR5A1 mutations were tested in vitro by promoter transactivation assays showing grossly reduced activity for mutations in the DNA binding domain and variably reduced activity for other mutations. Dominant negative effect of the mutations was excluded. We found high variability and thus no apparent genotype-structure-function-phenotype correlation. Histological studies of testes revealed vacuolization of Leydig cells due to fat accumulation. CONCLUSIONS SF-1/NR5A1 mutations are frequently found in 46,XY DSD individuals (9%) and manifest with a broad phenotype. Testes histology is characteristic for fat accumulation and degeneration over time, similar to findings observed in patients with lipoid congenital adrenal hyperplasia (due to StAR mutations). Genotype-structure-function-phenotype correlation remains elusive.

GNAS1 mutation and Cbfa1 misexpression in a child with severe congenital platelike osteoma cutis.

We evaluated a 7‐year‐old girl with severe platelike osteoma cutis (POC), a variant of progressive osseous heteroplasia (POH). The child had congenital heterotopic ossification of dermis and subcutaneous fat that progressed to involve deep skeletal muscles of the face, scalp, and eyes. Although involvement of skeletal muscle is a prominent feature of POH, heterotopic ossification has not been observed in the head, face, or extraocular muscles. The cutaneous ossification in this patient was suggestive of Albright hereditary osteodystrophy (AHO); however, none of the other characteristic features of AHO were expressed. Inactivating mutations of the GNAS1 gene, which encodes the α‐subunit of the stimulatory G protein of adenylyl cyclase, is the cause of AHO. Mutational analysis of GNAS1 using genomic DNA of peripheral blood and of lesional and nonlesional tissue from our patient revealed a heterozygous 4‐base pair (bp) deletion in exon 7, identical to mutations that have been found in some AHO patients. This 4‐bp deletion in GNAS1 predicts a protein reading frameshift leading to 13 incorrect amino acids followed by a premature stop codon. To investigate pathways of osteogenesis by which GNAS1 may mediate its effects, we examined the expression of the obligate osteogenic transcription factor Cbfa1/RUNX2 in lesional and uninvolved dermal fibroblasts from our patient and discovered expression of bone‐specific Cbfa1 messenger RNA (mRNA) in both cell types. These findings document severe heterotopic ossification in the absence of AHO features caused by an inactivating GNAS1 mutation and establish the GNAS1 gene as the leading candidate gene for POH.

Assay-dependent results of immunoassayable spontaneous 24-hour growth hormone secretion in short children.

ABSTRACT. Forty‐eight children, referred for evaluation of short stature, underwent 24‐hour spontaneous growth hormone (GH) secretion studies. The GH level in pooled sera was assessed for each child, using up to 11 commercial immunoassays. In a group of 15 children, the mean GH values obtained by nine of the assays were compared with the mean value given by a polyclonal radioimmunoassay (RIA) from Sorin: four gave higher results (p < 0.0001), three gave comparable results and two gave lower results (p < 0.001). The assay yielding the highest results (Nichols: 5.9 ± 2.3 ng/ml, mean ± SD) gave values that were approximately triple those obtained by the assay yielding the lowest results (Hybritech: 1.8 ± 0.8 ng/ml; p < 0.0001); both of these are monoclonal immunoradiometric assays (IRMAs). The GH concentrations measured in 24‐hour pools from 32 children using a monoclonal IRMA from Biomerieux were similar to those obtained using a polyclonal RIA from Farmos (2.8 ± 1.1 ng/ml and 2.9 ± 1.4 ng/ml, respectively) but significantly lower than those measured by another polyclonal RIA from Sorin (3.5 ±1.5 ng/ml). Two polyclonal assays (Biomérieux and Sorin) were then used to measure the GH levels in all of the 30‐minute samples and in the day, night and 24‐hour pools from the secretion studies of 22 children. The ratio of the results of the two assays remained fairly constant for a given child (although the GH levels in different 30‐minute samples differed considerably). However, the ratios between different children showed quite wide variation (from 2.03 to 1.04). It was concluded that the GH assay must be taken into account when evaluating data from GH secretion studies, and the disparity in the GH level measured by two or more assays may differ from child to child.

Vascular Endothelial Growth Factor Is Expressed in Human Fetal Growth Cartilage

Angiogenesis is a crucial event in endochondral ossification. Chemoattractants and mitogens for endothelial cells (such as basic fibroblast growth factor [bFGF] and transforming growth factor β [TGF‐β]), which act as local regulators of the process, are synthesized by chondrocytes under several stimuli and in relation to the differentiation stage of the cartilage. Vascular endothelial growth factor (VEGF) is a 44‐kDa protein well known as a potent angiogenic molecule owing to its mitogenic and permeability‐causing properties. In this work, VEGF was located by immunohistochemistry in growth plate cartilage of human fetuses (20–22 weeks old) and its expression was demonstrated by reverse‐transcription polymerase chain reaction (RT‐PCR). Primary culture of human fetal epiphyseal chondrocytes (HFEC) maintained VEGF expression at protein and messenger RNA (mRNA) levels and this expression was stimulated by cartilage‐promoting growth factors incorporated into the culture media (rFGF‐b, rTGF‐β1, and insulin‐like growth factor [rIGF‐I] at 50 ng/ml). The conditioned medium (CM) of HFEC stimulated the proliferation of endothelial cells, and this was partially blocked by anti‐VEGF antibody. These studies showed VEGF production by chondrocytes of the epiphyseal growth cartilage and suggested a role of this factor in cartilage physiology and the angiogenic process.

Novel associations in disorders of sex development: Findings from the I-DSD registry

Context: The focus of care in disorders of sex development (DSD) is often directed to issues related to sex and gender development. In addition, the molecular etiology remains unclear in the majority of cases. Objective: To report the range of associated conditions identified in the international DSD (I-DSD) Registry. Design, Setting, and Patients: Anonymized data were extracted from the I-DSD Registry for diagnosis, karyotype, sex of rearing, genetic investigations, and associated anomalies. If necessary, clarification was sought from the reporting clinician. Results: Of 649 accessible cases, associated conditions occurred in 168 (26%); 103 (61%) cases had one condition, 31 (18%) had two conditions, 20 (12%) had three conditions, and 14 (8%) had four or more conditions. Karyotypes with most frequently reported associations included 45,X with 6 of 8 affected cases (75%), 45,X/46,XY with 19 of 42 cases (45%), 46,XY with 112 of 460 cases (24%), and 46,XX with 27 of 121 cases (22%). In the 112 cases of 46,XY DSD, the commonest conditions included small for gestational age in 26 (23%), cardiac anomalies in 22 (20%), and central nervous system disorders in 22 (20%), whereas in the 27 cases of 46,XX DSD, skeletal and renal anomalies were commonest at 12 (44%) and 8 (30%), respectively. Of 170 cases of suspected androgen insensitivity syndrome, 19 (11%) had reported anomalies and 9 of these had confirmed androgen receptor mutations. Conclusions: Over a quarter of the cases in the I-DSD Registry have an additional condition. These associations can direct investigators toward novel genetic etiology and also highlight the need for more holistic care of the affected person.

Bone mass acquisition during infancy, childhood and adolescence

Osteoporosis is a common disease characterized by low bone mass and microarchitectural deterioration of bone tissue. As it increases bone fragility and, consequently, the risk of fracture, it constitutes a major health problem in the elderly. It has been estimated that a decrease in bone mineral content of 1 SD may significantly increase the risk of fractures of the long bones and/or vertebrae, with a consequent rise not only in morbidity and mortality of older people, but also in dependence on care from others ( I ) . Skeletal mineralization is an ongoing process during human fetal and postnatal development, stabilizing at about 21 years of age. Skeletal calcium content increases from 30 g in the neonate to 1200 g in the adult, and skeletal phosphorus from 17 g to 700 g (2). Bone tissue, unlike other tissues, possesses a series of enzymatic mechanisms that permit mineralization of its extracellular matrix (3, 4). Extracellular matrix is composed of collagen, proteoglycans and other non-collagen proteins in which insoluble mineral salts of hydroxyapatite and small amounts of other salts of magnesium, sodium carbonate and citrate are deposited, converting it into a structure capable of supporting the organism. Interaction between osteoblasts and osteoclasts is required for the formation and mineralization of the extracellular matrix, which is subject to constant remodelling due to the balance between mineral apposition and resorption (3, 4). This balance is clearly disposed towards apposition during infancy, childhood and adolescence, and remains constant thereafter until the later decades of life when it is tilted towards resorption, particularly in women after the menopause (1,5,6). There is increasing interest in the study of skeletal mineralization rates during childhood and adolescence, as these are the periods during which the major part of bone mass accumulates. Osteoporosis, a predominantly adult disease, may begin during childhood. Consequently, knowledge of normal mineralization patterns in children and adolescents is necessary to identify risk factors early and to design therapeutic protocols to prevent later development of osteoporosis. The human skeleton is not homogeneous. Two welldifferentiated components can be distinguished: the more compact cortical bone, which represents 80% of total bone mass, and trabecular or spongy bone, which forms the remaining 20%. Trabecular bone is located in the vertebrae, pelvis and other flat bones and is metabolically more active than cortical bone (7). Cortical bone predominates in the shafts of the long bones. The recent development of different bone densitometry techniques has facilitated non-invasive quantification of bone mass (see Slosman et al., this issue, pages 9-1 1). Furthermore, some of these techniques permit the study of bones, such as vertebral bodies, that have a greater trabecular component and are more sensitive to metabolic changes