Management and consequences of postoperative fluctuations in plasma sodium concentration after pediatric brain tumor surgery in the sellar region: a national cohort analysis.

PURPOSE: Severe fluctuations in plasma sodium concentration and plasma osmolarity, including central diabetes insipidus (CDI), may have significant influence on postoperative morbidity and mortality after pediatric brain tumor surgery.The aim of this study was to describe the frequency, severity and neurological consequences of these fluctuations in pediatric brain tumor survivors. METHODS: A retrospective, multi-institutional chart review was conducted among all children who underwent brain tumor surgery in the sellar or suprasellar region in seven university hospitals in the Netherlands between January 2004 and December 2013. RESULTS: Postoperative CDI was observed in 67.5% of 120 included children. Fluctuations of plasma sodium concentration ≥ 10 mmol/L/24 h during the first ten postoperative days were seen in 75.3% of patients with CDI, with a maximum delta of 46 mmol/L/24 h. When compared to patients without CDI, altered mental status occurred more frequently in patients with postoperative CDI (5.1 vs. 23.5% respectively, p = 0.009). Low plasma sodium concentration was related to altered mental status and the occurrence of seizures. Frequency and severity of fluctuations in plasma sodium concentration during the first ten postoperative days were significantly higher in patients with permanent CDI at last follow-up than in patients with transient CDI or without CDI (p = 0.007). CONCLUSION: Postoperative CDI is a common complication after pediatric brain tumor surgery in the sellar or suprasellar region. Extreme plasma sodium concentrations and large intra-day fluctuations still occur and seem to influence the postoperative neurological course. These results illustrate the need for intensive monitoring in a highly experienced center.

IGSF1 Deficiency: Lessons From an Extensive Case Series and Recommendations for Clinical Management.

CONTEXT: Mutations in the immunoglobulin superfamily, member 1 (IGSF1) gene cause the X-linked IGSF1 deficiency syndrome consisting of central hypothyroidism, delayed pubertal testosterone rise, adult macroorchidism, variable prolactin deficiency, and occasionally transient partial GH deficiency. Since our first reports, we discovered 20 new families with 18 new pathogenic IGSF1 mutations. OBJECTIVE: We aimed to share data on the largest cohort of patients with IGSF1 deficiency to date and formulate recommendations for clinical management. METHODS: We collected clinical and biochemical characteristics of 69 male patients (35 children, 34 adults) and 56 female IGSF1 mutation carriers (three children, 53 adults) from 30 unrelated families according to a standardized clinical protocol. At evaluation, boys were treated with levothyroxine in 89%, adult males in 44%, and females in 5% of cases. RESULTS: Additional symptoms in male patients included small thyroid gland volume (74%), high birth weight (25%), and large head circumference (20%). In general, the timing of pubertal testicular growth was normal or even premature, in contrast to a late rise in T levels. Late adrenarche was observed in patients with prolactin deficiency, and adult dehydroepiandrosterone concentrations were decreased in 40%. Hypocortisolism was observed in 6 of 28 evaluated newborns, although cortisol concentrations were normal later. Waist circumference of male patients was increased in 60%, but blood lipids were normal. Female carriers showed low free T4 (FT4) and low-normal FT4 in 18% and 60%, respectively, delayed age at menarche in 31%, mild prolactin deficiency in 22%, increased waist circumference in 57%, and a negative correlation between FT4 concentrations and metabolic parameters. CONCLUSION: IGSF1 deficiency represents the most common genetic cause of central hypothyroidism and is associated with multiple other characteristics. Based on these results, we provide recommendations for mutational analysis, endocrine work-up, and long-term care.

Mild deficits in attentional control in patients with the IGSF1 deficiency syndrome.

OBJECTIVE: Male patients with the X-linked IGSF1 deficiency syndrome are characterized by central hypothyroidism, delayed pubertal testosterone rise, adult macroorchidism, variable prolactin deficiency and occasionally transient partial growth hormone deficiency. Thyroid hormone plays a vital role in brain development and functioning, and while most patients receive adequate replacement therapy starting shortly after birth, it is unknown whether this syndrome is accompanied by long-term impaired cognitive functioning. We therefore assessed cognitive functioning in male patients with IGSF1 deficiency. METHODS: Fifteen adult male patients with IGSF1 deficiency participated in neuropsychological assessment of executive functioning and memory, and completed validated questionnaires on health-related quality of life (HRQoL), mood and fatigue. Results were compared to data from previous studies by our department: 54 healthy controls (76 for the attention task) for the test battery and 191 healthy controls for the questionnaires. RESULTS: All patients had central hypothyroidism, and twelve were treated with levothyroxine. Patients performed worse than controls in tasks that required attentional control (Trail Making Test, Letter-Digit Substitution Test, and Sustained Attention to Response Task) (all P < 0·001). Memory was unaffected. In addition, patients reported more mental fatigue and reduction of activity (Multidimensional Fatigue Inventory) (both P < 0·01), while HRQoL and mood reports were not different from controls. Age at the start of replacement therapy and current thyroxine levels were not related to outcome. CONCLUSIONS: Adult male patients with IGSF1 deficiency exhibit mild deficits in attentional control on formal testing. This finding was not related to the age at start of replacement therapy, or current levothyroxine treatment.

The growth response to GH treatment is greater in patients with SHOX enhancer deletions compared to SHOX defects.

OBJECTIVE: Short stature caused by point mutations or deletions of the short stature homeobox (SHOX) gene (SHOX haploinsufficiency (SHI)) is a registered indication for GH treatment. Patients with a SHOX enhancer deletion (SED) have a similar phenotype, but their response to GH is unknown. It is uncertain if duplications of SHOX or its enhancer (SDUP) cause short stature. This study aimed to describe the clinical characteristics and growth response to GH treatment in patients with aberrations of SHOX and its enhancers. DESIGN: In this retrospective multi-center study (2002-March 2014) clinical information was available from 130 patients (72 SHI, 44 SED, and 14 SDUP) of whom 52 patients were treated with GH. We evaluated height, sitting height (SH), arm span, dysmorphic features and indicators of the growth response to GH (delta height SDS, height velocity, and index of responsiveness). RESULTS: Patients with SEDs showed similar HtSDS to patients with SHI (-2.3 and -2.6, respectively, P=0.2), but they were less disproportionate (SH/height ratio SDS 2.0 vs 3.1 (P<0.01) and extremities/trunk ratio 2.57 vs 2.43 (P=0.03)). The 1st year growth response to GH treatment was significantly greater in prepubertal patients with SEDs than SHI. None of the patients with an SDUP was disproportionate and SDUP cosegregated poorly with short stature; their growth response to GH treatment (n=3) was similar to the other groups. CONCLUSIONS: Patients with SEDs are equally short, but less disproportionate than patients with SHI, and show a greater response to GH.

Bone mineral density in children and adolescents with Prader-Willi syndrome: a longitudinal study during puberty and 9 years of growth hormone treatment.

CONTEXT: Longitudinal data on bone mineral density (BMD) in children and adolescents with Prader-Willi Syndrome (PWS) during long-term GH treatment are not available. OBJECTIVE: This study aimed to determine effects of long-term GH treatment and puberty on BMD of total body (BMDTB), lumbar spine (BMDLS), and bone mineral apparent density of the lumbar spine (BMADLS) in children with PWS. DESIGN AND SETTING: This was a prospective longitudinal study of a Dutch PWS cohort. PARTICIPANTS: Seventy-seven children with PWS who remained prepubertal during GH treatment for 4 years and 64 children with PWS who received GH treatment for 9 years participated in the study. INTERVENTION: The children received GH treatment, 1 mg/m(2)/day (≅ 0.035 mg/kg/d). MAIN OUTCOME MEASURES: BMDTB, BMDLS, and BMADLS was measured by using the same dual-energy x-ray absorptiometry machine for all annual measurements. RESULTS: In the prepubertal group, BMDTB standard deviation score (SDS) and BMDLSSDS significantly increased during 4 years of GH treatment whereas BMADLSSDS remained stable. During adolescence, BMDTBSDS and BMADLSSDS decreased significantly, in girls from the age of 11 years and in boys from the ages of 14 and 16 years, respectively, but all BMD parameters remained within the normal range. Higher Tanner stages tended to be associated with lower BMDTBSDS (P = .083) and a significantly lower BMADLSSDS (P = .016). After 9 years of GH treatment, lean body mass SDS was the most powerful predictor of BMDTBSDS and BMDLSSDS in adolescents with PWS. CONCLUSIONS: This long-term GH study demonstrates that BMDTB, BMDLS, and BMADLS remain stable in prepubertal children with PWS but decreases during adolescence, parallel to incomplete pubertal development. Based on our findings, clinicians should start sex hormone therapy from the age of 11 years in girls and 14 years in boys unless there is a normal progression of puberty.

New insights into factors influencing adult height in short SGA children: Results of a large multicentre growth hormone trial.

BACKGROUND: Growth hormone (GH) treatment is effective in improving adult height (AH) in short children born SGA. However, there is a wide variation in height gain, even after adjustment for predictive variables. It is therefore important to investigate new factors which can influence the response to GH. OBJECTIVE: To investigate the efficacy of GH treatment (1 mg/m(2/) day) in short SGA children on AH. To assess the relation between spontaneous catch-up growth after birth and growth during puberty on the total height gain SDS to AH. PATIENTS: Longitudinal GH trial in 170 children. RESULTS: Median age at start of GH was 7·1 years and height -3·0 SDS. AH was -1·8 SDS (TH-corrected AH -1·1 SDS) in boys and -1·9 SDS (TH-corrected AH -1·3 SDS) in girls. Spontaneous catch-up growth after birth was ≥0·5 SDS in 42% of children. In contrast to expectation, spontaneous catch-up growth was negatively correlated with total height gain SDS during GH (P = 0·009). During puberty, height SDS declined (-0·4 SDS in boys and -0·5 SDS in girls) resulting in a lower total height gain SDS than expected. Pubertal height gain was 25·5 cm in boys and 15·3 cm in girls, significantly lower compared to AGA children (P < 0·001). At onset of puberty, BA for boys and girls was moderately advanced (P = 0·02 and P < 0·001, respectively). Growth velocity was comparable to AGA children during the first two years of puberty, but thereafter significantly lower until reaching AH (P < 0·001). CONCLUSION: In contrast to our hypothesis, children with greater spontaneous catch-up growth after birth show a lower total height gain SDS during GH. Height SDS declines from mid-puberty, due to a marked early deceleration of growth velocity.

Pseudoisodicentric Xp chromosome [46,X,psu idic(X)(q21.1)] and its effect on growth and pubertal development.

BACKGROUND: Most isodicentric (Xp) and (Xq) chromosomes occur as a mosaic with a 45,X cell line. Patients with a nonmosaic 46,X,idic(Xq) are rare. CASES: The first girl was referred at 13 years with a short stature and pubertal delay (M1, P2, A1). Her height was 141.6 cm (-3.1 SDS). Ovarian failure was present. The second girl was referred because of her short stature at 12.5 years. Her height was 142.2 cm (-2.4 SDS). She had spontaneous puberty (M3, P1, A1). RESULTS: In both girls, conventional karyotyping of lymphocytes revealed an aberrant X chromosome consisting of twice the short arm and a small part of the long arm of the X chromosome [nonmosaic 46,X,psu idic(X)(q21.1)]. FISH analysis of the aberrant X chromosome showed the presence of two centromeres, two copies of the XIST gene and two copies of the SHOX gene. CONCLUSIONS: The presence of two XIST genes on the isodicentric X chromosome with Xq deletion indicates the inactivation of this chromosome. This inactivation also concerned the pseudoautosomal regions which caused haploinsufficiency of the SHOX genes. The girls were treated with growth hormones. The critical region (Xq23 to Xq28) for the ovarian function was deleted in both patients, but the gonadal function was variable. .

The IGSF1 deficiency syndrome: characteristics of male and female patients.

CONTEXT: Ig superfamily member 1 (IGSF1) deficiency was recently discovered as a novel X-linked cause of central hypothyroidism (CeH) and macro-orchidism. However, clinical and biochemical data regarding growth, puberty, and metabolic outcome, as well as features of female carriers, are scarce. OBJECTIVE: Our objective was to investigate clinical and biochemical characteristics associated with IGSF1 deficiency in both sexes. METHODS: All patients (n = 42, 24 males) from 10 families examined in the university clinics of Leiden, Amsterdam, Cambridge, and Milan were included in this case series. Detailed clinical data were collected with an identical protocol, and biochemical measurements were performed in a central laboratory. RESULTS: Male patients (age 0-87 years, 17 index cases and 7 from family studies) showed CeH (100%), hypoprolactinemia (n = 16, 67%), and transient partial GH deficiency (n = 3, 13%). Pubertal testosterone production was delayed, as were the growth spurt and pubic hair development. However, testicular growth started at a normal age and attained macro-orchid size in all evaluable adults. Body mass index, percent fat, and waist circumference tended to be elevated. The metabolic syndrome was present in 4 of 5 patients over 55 years of age. Heterozygous female carriers (age 32-80 years) showed CeH in 6 of 18 cases (33%), hypoprolactinemia in 2 (11%), and GH deficiency in none. As in men, body mass index, percent fat, and waist circumference were relatively high, and the metabolic syndrome was present in 3 cases. CONCLUSION: In male patients, the X-linked IGSF1 deficiency syndrome is characterized by CeH, hypoprolactinemia, delayed puberty, macro-orchidism, and increased body weight. A subset of female carriers also exhibits CeH.

Eight years of growth hormone treatment in children with Prader-Willi syndrome: maintaining the positive effects.

BACKGROUND: The most important reason for treating children with Prader-Willi syndrome (PWS) with GH is to optimize their body composition. OBJECTIVES: The aim of this ongoing study was to determine whether long-term GH treatment can counteract the clinical course of increasing obesity in PWS by maintaining the improved body composition brought during early treatment. SETTING: This was a multicenter prospective cohort study. METHODS: We have been following 60 prepubertal children for 8 years of continuous GH treatment (1 mg/m(2)/d ≈ 0.035 mg/kg/d) and used the same dual-energy x-ray absorptiometry machine for annual measurements of lean body mass and percent fat. RESULTS: After a significant increase during the first year of GH treatment (P < .0001), lean body mass remained stable for 7 years at a level above baseline (P < .0001). After a significant decrease in the first year, percent fat SD score (SDS) and body mass index SDS remained stable at a level not significantly higher than at baseline (P = .06, P = .14, resp.). However, body mass index SDSPWS was significantly lower after 8 years of GH treatment than at baseline (P < .0001). After 8 years of treatment, height SDS and head circumference SDS had completely normalized. IGF-1 SDS increased to +2.36 SDS during the first year of treatment (P < .0001) and remained stable since then. GH treatment did not adversely affect glucose homeostasis, serum lipids, blood pressure, and bone maturation. CONCLUSION: This 8-year study demonstrates that GH treatment is a potent force for counteracting the clinical course of obesity in children with PWS.

Pharmacokinetics and pharmacodynamics of orally administered clonidine: a model-based approach.

BACKGROUND/AIMS: The oral clonidine test is a diagnostic procedure performed in children with suspected growth hormone (GH) deficiency. It is associated with untoward effects, including bradycardia, hypotension and sedation. Serum clonidine levels have not previously been assessed during this test. METHODS: In 40 children referred for an oral clonidine test, blood samples were drawn for clonidine and GH. Vital statistics and sedation scores were recorded until 210 min post-dose. We explored the relationship between clonidine concentrations and effects such as GH peak and blood pressure. RESULTS: Of 40 participants, 5 children were GH deficient. Peak clonidine concentrations of 0.846 ± 0.288 ng/ml were reached after 1 h. Serum levels declined slowly, with concentrations of 0.701 ± 0.189 ng/ml 210 min post-dose. A large interindividual variation of serum levels was observed. During the procedure, systolic blood pressure dropped by 12.8%, diastolic blood pressure by 19.7% and heart rate by 8.4%. Moderate sedation levels were observed. Concentration-effect modeling showed that the amount of GH available for secretion as determined by previous bursts was an important factor influencing GH response. CONCLUSION: Clonidine concentrations during the test were higher than necessary according to model-based predictions. A lower clonidine dose may be sufficient and may produce fewer side effects.

Variable loss of functional activities of androgen receptor mutants in patients with androgen insensitivity syndrome.

Androgen receptor (AR) mutations in androgen insensitivity syndrome (AIS) are associated with a variety of clinical phenotypes. The aim of the present study was to compare the molecular properties and potential pathogenic nature of 8 novel and 3 recurrent AR variants with a broad variety of functional assays. Eleven AR variants (p.Cys177Gly, p.Arg609Met, p.Asp691del, p.Leu701Phe, p.Leu723Phe, p.Ser741Tyr, p.Ala766Ser, p.Arg775Leu, p.Phe814Cys, p.Lys913X, p.Ile915Thr) were analyzed for hormone binding, transcriptional activation, cofactor binding, translocation to the nucleus, nuclear dynamics, and structural conformation. Ligand-binding domain variants with low to intermediate transcriptional activation displayed aberrant Kd values for hormone binding and decreased nuclear translocation. Transcriptional activation data, FxxFF-like peptide binding and DNA binding correlated well for all variants, except for p.Arg609Met, p.Leu723Phe and p.Arg775Leu, which displayed a relatively higher peptide binding activity. Variants p.Cys177Gly, p.Asp691del, p.Ala766Ser, p.Phe814Cys, and p.Ile915Thr had intermediate or wild type values in all assays and showed a predominantly nuclear localization in living cells. All transcriptionally inactive variants (p.Arg609Met, p.Leu701Phe, p.Ser741Tyr, p.Arg775Leu, p.Lys913X) were unable to bind to DNA and were associated with complete AIS. Three variants (p.Asp691del, p.Arg775Leu, p.Ile915Thr) still displayed significant functional activities in in vitro assays, although the clinical phenotype was associated with complete AIS. The data show that molecular phenotyping based on 5 different functional assays matched in most (70%) but not all cases.

Spectrum of insulin-like growth factor deficiency.

There are eight known genetic causes of short stature characterized by low serum IGF-1 (IGF-1 deficiency, IGFD) and normal GH secretion. One of these (GHSR defect) is a form of secondary IGFD, although the GH peak in provocation tests can be normal. Bioinactive GH (GH1 mutations) can disturb GH secretion, but also GH binding and signaling. The remaining conditions are classified as primary IGFD (GH insensitivity). The clinical phenotype of GH receptor (GHR) defects is variable. Of the three GH signal transduction defects, a STAT5B defect is well established, but abnormalities in the MAPK pathway (such as PTPN11 mutations in Noonan syndrome) and NF-ĸB pathway (IĸBα mutation) may also cause IGFD. Homozygous IGFALS defects are relatively common, and lead to moderate growth failure, very low serum IGF-1 and even lower IGFBP-3, while a heterozygous IGFALS mutation decreases height by 1 SD. Most cases with a homozygous IGF1 defect are very short, microcephalic, and deaf, but heterozygous mutations may also lead to short stature. IGFD can also have a digenic or oligogenic origin. The diagnostic yield of genetic testing in children with a height <-2.5 SDS and a serum IGF-1 <-2 appears sufficient to perform genetic tests for known candidate genes.

Genetic analysis of short children with apparent growth hormone insensitivity.

BACKGROUND/AIMS: In short children, a low IGF-I and normal GH secretion may be associated with various monogenic causes, but their prevalence is unknown. We aimed at testing GH1, GHR, STAT5B, IGF1, and IGFALS in children with GH insensitivity. SUBJECTS AND METHODS: Patients were divided into three groups: group 1 (height SDS <-2.5, IGF-I <-2 SDS, n = 9), group 2 (height SDS -2.5 to -1.9, IGF-I <-2 SDS, n = 6) and group 3 (height SDS <-1.9, IGF-I -2 to 0 SDS, n = 21). An IGF-I generation test was performed in 11 patients. Genomic DNA was used for direct sequencing, multiplex ligation-dependent probe amplification and whole-genome SNP array analysis. RESULTS: Three patients in group 1 had two novel heterozygous STAT5B mutations, in two combined with novel IGFALS variants. In groups 2 and 3 the association between genetic variants and short stature was uncertain. The IGF-I generation test was not predictive for the growth response to GH treatment. CONCLUSION: In severely short children with IGF-I deficiency, genetic assessment is advised. Heterozygous STAT5B mutations, with or without heterozygous IGFALS defects, may be associated with GH insensitivity. In children with less severe short stature or IGF-I deficiency, functional variants are rare.

A mosaic de novo duplication of 17q21-25 is associated with GH insensitivity, disturbed in vitro CD28-mediated signaling, and decreased STAT5B, PI3K, and NF-κB activation.

OBJECTIVE: The established causes of GH insensitivity include defects of the GH receptor and STAT5B. The latter condition is also characterized by severe immunodeficiency. A recent case with short stature, GH resistance, and immunodeficiency due to an IκB mutation suggests that the NF-κB pathway may interact with STAT5B signaling. DESIGN: Here, we present a case of a short child with several congenital anomalies as well as GH insensitivity and mild immunodeficiency associated with a mosaic de novo duplication of chromosome 17q21-25, suggesting that overexpression of one of the duplicated genes may be implicated in GH resistance. METHODS AND RESULTS: In vitro studies on blood lymphocytes showed disturbed signaling of the CD28 pathway, involving NF-κB and related proteins. Functional studies on cultured skin fibroblasts revealed that NF-κB activation, PI3K activity, and STAT5 phosphorylation in response to GH were suppressed, while the sensitivity to GH in terms of MAPK phosphorylation was increased. An in silico analysis of the duplicated genes showed that MAP3K3 and PRKCA are associated with the NF-κB pathway. Baseline MAP3K3 expression in T-cell blasts (TCBs) was normal, but PRKCA expression in TCBs and fibroblasts was significantly higher than that in control cells. CONCLUSIONS: We conclude that the 17q21-25 duplication is associated with GH insensitivity and disturbed STAT5B, PI3K, and NF-κB signaling, possibly due to PRKCA mRNA overexpression.

Inhibition of Gsk3ß in cartilage induces osteoarthritic features through activation of the canonical Wnt signaling pathway.

OBJECTIVE: In the past years, the canonical Wnt/ß-catenin signaling pathway has emerged as a critical regulator of cartilage development and homeostasis. In this pathway, glycogen synthase kinase-3ß (GSK3ß) down-regulates transduction of the canonical Wnt signal by promoting degradation of ß-catenin. In this study we wanted to further investigate the role of Gsk3ß in cartilage maintenance. DESIGN: Therefore, we have treated chondrocytes ex vivo and in vivo with GIN, a selective GSK3ß inhibitor. RESULTS: In E17.5 fetal mouse metatarsals, GIN treatment resulted in loss of expression of cartilage markers and decreased chondrocyte proliferation from day 1 onward. Late (3 days) effects of GIN included cartilage matrix degradation and increased apoptosis. Prolonged (7 days) GIN treatment resulted in resorption of the metatarsal. These changes were confirmed by microarray analysis showing a decrease in expression of typical chondrocyte markers and induction of expression of proteinases involved in cartilage matrix degradation. An intra-articular injection of GIN in rat knee joints induced nuclear accumulation of ß-catenin in chondrocytes 72 h later. Three intra-articular GIN injections with a 2 days interval were associated with surface fibrillation, a decrease in glycosaminoglycan expression and chondrocyte hypocellularity 6 weeks later. CONCLUSIONS: These results suggest that, by down-regulating ß-catenin, Gsk3ß preserves the chondrocytic phenotype, and is involved in maintenance of the cartilage extracellular matrix. Short term ß-catenin up-regulation in cartilage secondary to Gsk3ß inhibition may be sufficient to induce osteoarthritis-like features in vivo.

The severe short stature in two siblings with a heterozygous IGF1 mutation is not caused by a dominant negative effect of the putative truncated protein.

OBJECTIVE: While in previous studies heterozygosity for an Insulin-Like Growth Factor 1 (IGF1) defect only modestly decreased height and head circumference, we recently reported on two siblings with severe short stature with a maternally transmitted heterozygous duplication of 4 nucleotides, resulting in a frame shift and a premature termination codon in the IGF1 gene. In this paper we describe the structural and functional characteristics of the putative truncated IGF-I protein. DESIGN: Two children, their mother and maternal grandfather carried the mutation. In addition, two family members who were not affected were included in the study. Mutant (MT) IGF-I was synthesized in oxidized and reduced form using two methods. Neutral gel filtration studies were carried out with wild-type (WT) and synthetic MT IGF-I. Binding analysis of synthetic MT IGF-I to the IGF1R and insulin receptors were performed with EBNA-293 cells, stably transfected with the IGF-I receptor, and IM9 cells. L6 cells were used to examine the mitogenic potency and the potential antagonizing effect of synthetic MT IGF-I by [(3)H]-thymidine incorporation assays. RESULTS: In the sera of both the carriers and non-carriers the proportion of (125)I-IGF-I that was associated with the 150 kDa complex was somewhat less (varying between ~37 and ~52%) than in normal pooled serum (~53-~63%) and, instead, slightly increased amounts of radioactivity were eluted in the 40-50 kDa fraction (consisting of binary IGF-IGFBP complexes) or remained unbound. Synthetic MT IGF-I did not bind to the IGF-I receptor, nor antagonize the growth-promoting effect of IGF-I. It did bind to IGFBPs, but was barely incorporated into 150 kDa complexes. Because in all cases WT IGF-I immunoreactivity was recovered in one peak, corresponding to the MW of WT IGF-I, i.e. ~7.6 kDa, an interaction of circulating truncated mutant peptide with WT IGF-I is very unlikely. CONCLUSIONS: There is no evidence that the severe short stature associated with heterozygosity for this novel IGF1 mutation in children born from a mother with the same mutation is caused by a dominant negative effect of the truncated protein. We speculate that the growth failure is caused by a combination of partial IGF-I deficiency, placental IGF-I insufficiency, and other genetic factors.

Should blood gas analysis be part of the diagnostic workup of short children? Auxological data and blood gas analysis in children with renal tubular acidosis.

BACKGROUND: Renal tubular acidosis (RTA) is a rare cause of growth failure, therefore it is uncertain whether routine screening with blood gas analysis of short infants and children is cost-effective. OBJECTIVE: To investigate the clinical, growth and laboratory parameters in children with RTA to estimate the possible value of laboratory screening for this disorder in infants and children referred for short stature according to a recent guideline. METHOD: Retrospective chart analysis of 30 children diagnosed between 1978 and 2005 in The Netherlands and 3 centers in Belgium. RESULTS: The current guideline for short stature detected 33% of children with RTA. Assuming a pre-test probability of RTA of 0.6 per 100,000 births, the likelihood ratio of poor growth was 58 and 17 below and above 3 years, respectively. Sensitivity was 17/30 and 12/24 for a -2.0 SDS cutoff for weight and body mass index, respectively. In infants and toddlers diagnosed before 3 years of age, the mean weight loss was 1.5 SD, and 0.8 SDS in older children. In short children >3 years RTA was extremely rare, always associated with clinical symptoms, and rarely detected by blood gas analysis. CONCLUSION: According to our data a decreasing weight SDS for age is a sufficient indication to perform blood gas analysis in children <3 years of age, particularly in the presence of additional clinical features, whereas it can be omitted in short children >3 years of age.

Short stature associated with a novel heterozygous mutation in the insulin-like growth factor 1 gene.

CONTEXT: Homozygous IGF1 deletions or mutations lead to severe short stature, deafness, microcephaly, and mental retardation. Heterozygosity for an IGF-I defect may modestly decrease height and head circumference. OBJECTIVE: The objective of the study was to investigate the clinical features of heterozygous carriers of a novel mutation in the IGF1 gene in comparison with noncarriers in a short family and to establish the effect of human GH treatment. SUBJECTS: Two children, their mother, and their maternal grandfather carried the mutation and were compared with two relatives who were noncarriers. RESULTS: The two index cases had severe short stature (height sd score -4.1 and -4.6), microcephaly, and low IGF-I levels. Sequencing of IGF1 revealed a heterozygous duplication of four nucleotides, resulting in a frame shift and a premature termination codon. The mother and maternal grandfather had the same IGF1 mutation. Adult height (corrected for shrinking and secular trend) and head circumference sd score of carriers of the paternally transmitted mutation was -2.5 and -1.8, in comparison with -1.6 and 0.3 in noncarriers, respectively. After 2 yr of GH treatment, both index cases exhibited increased growth. CONCLUSIONS: Heterozygosity for this novel IGF1 mutation in children born from a mother with the same mutation, presumably in combination with other genetic factors for short stature, leads to severe short stature, which can be successfully treated with GH.

High-dose GH treatment limited to the prepubertal period in young children with idiopathic short stature does not increase adult height.

OBJECTIVE: To assess the long-term effect of prepubertal high-dose GH treatment on growth in children with idiopathic short stature (ISS). DESIGN AND METHODS: Forty children with no signs of puberty, age at start 4-8 years (girls) or 4-10 years (boys), height SDS <-2.0 SDS, and birth length >-2.0 SDS, were randomly allocated to receive GH at a dose of 2 mg/m(2) per day (equivalent to 75 microg/kg per day at start and 64 microg/kg per day at stop) until the onset of puberty for at least 2 years (preceded by two 3-month periods of treatment with low or intermediate doses of GH separated by two washout periods of 3 months) or no treatment. In 28 cases, adult height (AH) was assessed at a mean (S.D.) age of 20.4 (2.3) years. RESULTS: GH-treated children (mean treatment period on high-dose GH 2.3 years (range 1.2-5.0 years)) showed an increased mean height SDS at discontinuation of the treatment compared with the controls (-1.3 (0.8) SDS versus -2.6 (0.8) SDS respectively). However, bone maturation was significantly accelerated in the GH-treated group compared with the controls (1.6 (0.4) versus 1.0 (0.2) years per year, respectively), and pubertal onset tended to advance. After an untreated interval of 3-12 years, AH was -2.1 (0.7) and -1.9 (0.6) in the GH-treated and control groups respectively. Age was a positive predictor of adult height gain. CONCLUSION: High-dose GH treatment restricted to the prepubertal period in young ISS children augments height gain during treatment, but accelerates bone maturation, resulting in a similar adult height compared with the untreated controls.