J J Heinrich

Cutting Edge: Decreased Accumulation and Regulatory Function of CD4+CD25high T Cells in Human STAT5b Deficiency

We show that STAT5b is important for the in vivo accumulation of CD4+CD25high T cells with regulatory cell function. A patient homozygous for a missense A630P STAT5b mutation displayed immune dysregulation and decreased numbers of CD4+CD25high T cells. STAT5bA630P/A630P CD4+CD25high T cells had low expression of forkhead box P3 and an impaired ability to suppress the proliferation of or to kill CD4+CD25− T cells. Expression of CD25, a component of the high-affinity IL-2R, was also reduced in response to IL-2 or after in vitro propagation. The impact of the STAT5b mutation was selective in that IL-2-mediated up-regulation of the common γ-chain cytokine receptor and perforin, and activation-induced expressions of CD154 and IFN-γ were normal. These results indicate that STAT5b propagates an important IL-2-mediated signal for the in vivo accumulation of functional regulatory T cells.

Differential impact of simple childhood obesity on the components of the growth hormone-insulin-like growth factor (IGF)-IGF binding proteins axis.

Simple childhood obesity is characterized by normal or even accelerated growth in spite of reduced growth hormone (GH) secretion. There are conflicting reports on the effects of obesity upon components of the GH-insulin-like growth factor-I (IGF-I)-IGF binding proteins (IGFBPs) system. In the present study we aimed to determine GH, IGF-I, IGFBP-3 and IGFBP-2 as well as some of the less explored components of this axis (IGFBP-3 proteolytic activity, IGFBP-3 plasma fragments, and total acid labile subunit [ALS]) in 22 obese and 17 age-matched control children. We also evaluated not only total GH binding protein (GHBP) serum levels but also GHBP bound to GH (complexed) in both groups. Obese and control groups strongly differed in BMI (obese: 4.7 +/- 0.36 vs control: 0.37 +/- 0.25 SDS, p <0.0001). In the obese group, we found lower GH serum levels, but normal serum levels of GH-GHBP complex, IGF-I, IGFBP-3, IGF-I/IGFBP-3 molar ratio, IGFBP-3 proteolytic activity, IGFBP-3 plasma fragments and total ALS. Obese children presented higher total circulating GHBP (6.0 +/- 0.44 vs 2.9 +/- 0.29 nmol/l, p <0.001) and insulin levels (10.5 +/- 1.5 vs 5.1 +/- 0.8 mU/l, p <0.001), while IGFBP-2 (4.6 +/- 0.5 vs 6.6 +/- 0.7%, p <0.05) and the ratio IGFBP-2/IGF-I (0.032 +/- 0.019 vs 0.095 +/- 0.01, p = 0.013) were lower than in controls. BMI and insulin were directly, and IGFBP-2 serum levels inversely, correlated to total GHBP serum levels when multiple regression analysis was performed (r = 0.74, p <0.001). By stepwise regression analysis, insulin (r = -0.37, p <0.05) and BMI (r = -0.52, p <0.01) inversely determined IGFBP-2. In summary, obese children present normal growth in spite of reduced GH secretion, probably because the combination of increased total GHBP and normal GH-GHBP complex serum levels (suggesting increased GH receptor [GHR] number and a normal serum GH reservoir, respectively) allow for the achievement of normal levels of IGF-I, IGFBP-3, IGFBP-3 proteolytic activity, IGFBP-3 plasma fragments and total ALS. Reduced IGFBP-2 serum levels and a lower ratio of IGFBP-2/IGF-I in obese children may suggest an increase of tissue IGF-I bioavailability, thus promoting its action. Normal IGF-I and GH availability may be contributing to maintain normal growth in obese children.

Nocturnal TSH Surge and TRH Test Response in the Evaluation of Thyroid Axis in Hypothalamic Pituitary Disorders in Childhood

We studied, by means of TSH nocturnal secretion and TRH test, 42 children (4.2–19.9 years) with hypothalamic pituitary disorders and 24 healthy euthyroid children (5.7–15.4 years) as control group. Patients were divided according to their serum values of FT4 in group 1 (n = 27) with FT4 ≥10.3 pmol/l and group 2 (n = 15) with FT4 <10.3 pmol/l. TSH was measured by immunoradiometric assay. TSH nadir, TSH peak and TSH surge were calculated. Both groups differed significantly from control group in TSH surge values: group 1 (p < 0.05), group 2 (p < 0.01). TRH test was abnormal in 11/27 patients of group 1 and 10/15 patients of group 2. In group 1, 7 patients had normal tests, 2 had abnormalities in both tests, 9 had only TSH nocturnal surge altered and 9 showed only TRH alterations. All patients of group 2 presented thyroid axis abnormalities. In conclusion, in patients with hypothalamic pituitary disorders with low FT4, no further investigation is required to demonstrate thyroid axis alterations, however in patients with normal FT4, nocturnal TSH secretion and TRH test may be required to evidence thyroid abnormalities.

Long-term endocrine sequelae after surgery, radiotherapy, and chemotherapy in children with medulloblastoma

Thirteen children with medulloblastoma, were studied after 2 to 62 months off radiotherapy and chemotherapy with methotrexate and BCNU. Ages at time of study ranged from 2.3 to 15.7 years. Eleven patients, followed for a mean of 22 months, showed a significant decrease of height score, whereas nine patients had deficient growth hormone (GH) response to provocative tests. Clinical pubertal progression was normal in all patients, and three of five girls with advanced pubertal development had menarche. No evidences of gonadotropin disturbances were found in five patients whereas seven had raised basal folliclestimulating hormone (FSH) level or FSH response to luteinizing hormone‐releasing hormone (LH‐RH). Abnormalities in thyrotrophin (TSH) secretion were found in 9 of 13 patients. This study shows that poor growth and GH deficiency were frequent in our patients. The high frequency of thyroid disturbances observed point out the need of evaluating thyroid function for adequate replacement therapy. Perhaps modification of adjuvant chemotherapy in the future can diminish drug‐induced gonadal damage. Cancer 59:801‐806, 1987.

Normal Growth Spurt and Final Height despite Low Levels of All Forms of Circulating Insulin-Like Growth Factor-I in a Patient with Acid-Labile Subunit Deficiency

Background: In a recently described patient with acid-labile subunit (ALS) deficiency, the inability to form ternary complexes resulted in a marked reduction in circulating total insulin-like growth factor (IGF)-I, whereas skeletal growth was only marginally affected. To further study the role of circulating versus locally produced IGF-I in skeletal growth in this patient, we now describe in detail growth changes and their relationship with several components of the circulating IGF system. Design and Methods: We followed growth and development up to the final height in a patient with complete ALS deficiency and determined both spontaneous and growth hormone (GH)-stimulated changes in the IGF system, including measurements of total, free and bioactive IGF-I, total IGF-II and insulin-like growth factor binding protein (IGFBP)-1, IGFBP-2 and IGFBP-3. Results: The patient had a delayed growth and pubertal onset. Six months of GH treatment had no effect on growth. At the age of 19.3 years, he spontaneously completed puberty and had a normal growth spurt for a late adolescent (peak height velocity of 8.4 cm/year). A normal final height was attained at 21.3 years (167.5 cm; –0.78 SDS). During as well as after puberty, basal levels of total, free and bioactive IGF-I were low, as were total IGF-II, IGFBP-1, IGFBP-2 and IGFBP-3. GH treatment for 6 months normalized free IGF-I and increased bioactive IGF-I, but had no effect on growth velocity. Conclusions: This case story shows that in the presence of complete ALS deficiency, a height within normal limits can be obtained despite low levels of all forms of circulating IGF-I. Furthermore, the patient presented a delayed but normal growth spurt without any marked increment of circulating IGF-I.

The C105fs114X Is the Prevalent Thyrotropin Beta-Subunit Gene Mutation in Argentinean Patients with Congenital Central Hypothyroidism

Background: Congenital isolated thyrotropin (TSH) deficiency is an unusual condition characterized by low levels of thyroid hormones and TSH, usually presenting early typical signs of severe hypothyroidism. Five different β-TSH mutations have been described so far. While 4 of them affect only consanguineous families, a frameshift mutation in exon 3 (C105fs114X) has been found also in nonconsanguineous families. Objective: The aim of the present study was to characterize β-TSH mutations in Argentinean patients with congenital central hypothyroidism (CCH) and to emphasize the importance of early biochemical and molecular diagnosis of this disorder. Patients and Methods: We investigated 8 Argentinean children (3 boys, 5 girls) from 7 unrelated families with CCH based upon low levels of T4 and T3, and low basal and stimulated TSH levels. Mutation characterizations for the β-TSH gene were performed by PCR amplification followed by sequence and restriction enzyme analysis with SnaBI in the patients, 9 parents and in 100 newborn children. Results: All patients presented the same homozygous mutation in exon 3 of the β-TSH gene (C105fs114X), the 9 studied parents were heterozygous for the same mutation and 1 carrier was found in the 100 studied newborns. Conclusion: Our findings show that the C105fs114X mutation is prevalent in our population and may constitute a hot spot at codon 105 in the β-TSH gene. Since this mutation is easily demonstrable by a SnaBI digestion in DNA amplified from dried blood spots, its investigation would be indicated in patients in our milieu with clinical and biochemical features of CCH, allowing early L-thyroxine (LT4) replacement and genetic counseling of the family.

Heterozygous IGFALS Gene Variants in Idiopathic Short Stature and Normal Children: Impact on Height and the IGF System

Background: In acid-labile subunit (ALS)-deficient families, heterozygous carriers of IGFALS gene mutations are frequently shorter than their wild-type relatives, suggesting that IGFALS haploinsufficiency could result in short stature. We have characterized IGFALS gene variants in idiopathic short stature (ISS) and in normal children, determining their impact on height and the IGF system. Patients and Methods: In 188 normal and 79 ISS children levels of IGF-1, IGFBP-3, ALS, ternary complex formation (TCF) and IGFALS gene sequence were determined. Results: In sum, 9 nonsynonymous or frameshift IGFALS variants (E35Gfs*17, G83S, L97F, R277H, P287L, A330D, R493H, A546V and R548W) were found in 10 ISS children and 6 variants (G170S, V239M, N276S, R277H, G506R and R548W) were found in 7 normal children. If ISS children were classified according to the ability for TCF enhanced by the addition of rhIGFBP-3 (TCF+), carriers of pathogenic IGFALS gene variants were shorter and presented lower levels of IGF-1, IGFBP-3 and ALS in comparison to carriers of benign variants. In ISS families, subjects carrying pathogenic variants were shorter and presented lower IGF-1, IGFBP-3 and ALS levels than noncarriers. Conclusions: These findings suggest that heterozygous IGFALS gene variants could be responsible for short stature in a subset of ISS children with diminished levels of IGF-1, IGFBP-3 and ALS.

Reproducibility and comparison of growth hormone secretion tests.

To assess the degree of reproducibility of spontaneous GH secretion and pharmacological tests we studied 15 prepubertal children with short stature and abnormal growth rate. In all children, spontaneous overnight GH secretion was measured followed by a clonidine test in 8 children and an arginine test in the remaining 7. The same protocol was repeated a week later. Intra-individual variability of GH secretion in both physiological and pharmacological tests was expressed as the coefficient of variation (CV%). No significant difference was found between the first and second value of parameters of spontaneous GH secretion. Maximum spontaneous GH peak (MS) and mean 12-h GH concentration (MGH) correlated significantly (r = 0.78, p < 0.001). Mean CV% of all parameters of repeated GH profiles (around 30%) were lower than those of provocative tests (around 70%) (p < 0.05). No significant difference was found between CV% of clonidine and arginine tests. There was no correlation between MGH or MS and GH response to provocative test in the same child. We found a significant correlation between the log transformed maximum provocative GH response to the arginine test and the length of the time interval (in min) from the end of the last GH peak in the previous profile to the time zero of the provocative test (r = 0.60, p < 0.05). This relationship was not found for the clonidine test. We conclude that spontaneous GH secretion in children with short stature is more reproducible than stimulated GH response with a weeks difference. Perhaps the higher variability of provocative GH secretion may be related to the state of the endogenous hypothalamic rhythm of both GHRH and somatostatin release at the time of the test.

Trisomy of the Short Stature Homeobox-Containing Gene (SHOX) due to Duplication/Deletion of the X Chomosome: Clinical Implications on the Stature

Background: The karyotypes of 2 patients with abnormal stature and different phenotypes revealed one similar structural abnormality in the X chromosome by conventional cytogenetic studies and fluorescence in situ hybridization analysis (FISH). FISH strongly suggested the presence of two copies of the SHOX gene in the der(X) chromosome. Patients and Results: Patient 1 is a teenager girl with tall stature, behavioral disturbances and normal pubertal development. The abnormal X chromosome was present in all cells studied. Parent’s karyotypes were normal. Patient 2 is a girl with gonadal dysgenesis, mild Turner syndrome phenotype and short stature. The karyotype was a mosaic 45,X/46,X,r(X) and der(X) chromosome presented in most metaphases of the cell lines. Parent’s karyotypes were normal. Nearly all duplication of Xp and partial deletion of the long arm (Xq) from Xq27 or Xq21 to Xqter, in cases 1 and 2, respectively, were observed. In both patients, duplication of Xp translocated to deleted Xq occurred leading to a triplication of the pseudoautosomal region 1 (PAR1) where the SHOX gene is located (Xp22.3). Conclusions: We propose that in some cases of trisomy for the SHOX gene, the effect of overdosage per se may affect the stature, even in patients with preserved ovarian function (case 1), and that estrogen deprivation may not always be a contributor for tall stature (case 2).

Identification of the first patient with a confirmed mutation of the JAK-STAT system

Growth hormone insensitivity (GHI) has been attributable, classically, to mutations in the gene for the GH receptor. After binding to the GH receptor, GH initiates signal transduction through a number of pathways, including the JAK-STAT pathway. We describe the first patient reported with a mutation in the gene for STAT5b, a protein critical for the transcriptional regulation of insulin-like growth factor-I.