Limb lengthening in children with Russell-Silver syndrome: a comparison to other etiologies.

INTRODUCTION/BACKGROUND: Russell-Silver syndrome (RSS) is the combination of intrauterine growth retardation, difficulty feeding, and postnatal growth retardation. Leg length discrepancy (LLD) is one of four major diagnostic criteria of RSS and is present in most cases. We aimed to ascertain whether pediatric RSS patients will adequately consolidate bony regenerate following leg lengthening. MATERIALS AND METHODS: We retrospectively reviewed pediatric RSS patients who underwent limb lengthening and compared them to a similar group of patients with LLD resulting from tumor, trauma, or congenital etiology. The primary outcome measurement was the bone healing index (BHI). RESULTS: The RSS group included seven lengthened segments in five patients; the comparison group included 21 segments in 19 patients. The groups had similar lengthening amounts (3.3 vs. 3.9 cm, p = 0.507). The RSS group healed significantly faster (lower BHI) than the control group (BHI 29 vs. 43 days/cm, p = 0.028). Secondary analysis showed no difference between RSS and trauma patients in terms of the BHI (29 vs. 31); however, the BHI of the RSS group was significantly lower than both of the other congenital etiologies (29 vs. 41, p = 0.032) and tumor patients (29 vs. 66, p = 0.019). The RSS patients had fewer and less significant complications than the controls. DISCUSSION: The limb lengthening regenerate healing of RSS patients is faster than the healing of patients with other congenital etiologies and tumor patients, and is as fast as the regenerate healing of patients with posttraumatic LLD. Although all RSS patients were treated with human growth hormone (hGH), we are unable to isolate the hGH contribution to the regenerate bone healing. We conclude that RSS patients can have safe limb lengthening.

Growth hormone therapy alone or in combination with gonadotropin-releasing hormone analog therapy to improve the height deficit in children with congenital adrenal hyperplasia.

Short stature in the adult patient with congenital adrenal hyperplasia (CAH) is commonly seen, even among patients in excellent adrenal control during childhood and puberty. In this study we examine the effect of GH therapy on height prediction in children with both CAH and compromised height prediction. Leuprolide acetate, a GnRH analog (GnRHa), was given to patients with evidence of early puberty. GH (n = 12) or the combination of GH and GnRHa (n = 8) was administered to 20 patients with CAH while they continued therapy with glucocorticoids. Each patient in the treatment group was matched according to age, sex, bone age, puberty, and type of CAH with another CAH patient treated only with glucocorticoid replacement. The match was made at the start of GH treatment. Of the 20 patients, 12 have completed 2 yr of therapy. After 1 yr of GH or combination GH and GnRHa therapy, the mean growth rate increased from 5 +/- 1.9 to 7.8 +/- 1.6 cm/yr vs. 5.4 +/- 1.7 to 5 +/- 2 cm/yr in the group not receiving GH (P < 0.0001). During the second year of treatment, the mean growth rate was 6 +/- 1.6 vs. 4.2 +/- 2.1 cm/yr in the group not receiving GH (P < 0.001). The height SD score for chronological age in the treatment group at the end of 1 and 2 yr of treatment improved significantly more than the nontreatment group (P < 0.01). A similar improvement in the height SD score for bone age was found in the treatment group after 1 (-1.4 +/- 0.9 vs. -1.7 +/- 0.9; P < 0.0001) and 2 yr of therapy (-0.67 +/- 0.68 vs. -1.7 +/- 1.2; P < 0.0004). The mean predicted adult height improved from 159 +/- 11 (baseline) to 170 +/- 7.5 cm (after 2 yr of therapy) closely approximating target height (173 +/- 8 cm). All patients continued the hydrocortisone treatment. In patients with CAH and compromised height prediction, treatment with GH or the combination of GH and GnRHa results in an improvement of growth rate and height prediction and a reduction in height deficit for bone age.

Examination of genotype and phenotype relationships in 14 patients with apparent mineralocorticoid excess.

Apparent mineralocorticoid excess (AME) is a genetic disorder causing pre- and postnatal growth failure, juvenile hypertension, hypokalemic metabolic alkalosis, and hyporeninemic hypoaldosteronism due to a deficiency of 11 beta-hydroxysteroid dehydrogenase type 2 enzyme activity (11 beta HSD2). The 11 beta HSD2 enzyme is responsible for the conversion of cortisol to the inactive metabolite cortisone and therefore protects the mineralocorticoid receptors from cortisol intoxication. Several homozygous mutations are associated with this potentially fatal disease. We have examined the phenotype, biochemical features, and genotype of 14 patients with AME. All of the patients had characteristic signs of a severe 11 beta HSD2 defect. Birth weights were significantly lower than those of their unaffected sibs. The patients were short, underweight, and hypertensive for age. Variable damage of one or more organs (kidneys, retina, heart, and central nervous system) was found in all of the patients except one. The follow-up studies of end-organ damage after 2-13 yr of treatment in six patients demonstrated significant improvement in all patients. The urinary metabolites of cortisol demonstrated an abnormal ratio with predominance of cortisol metabolites, i.e. tetrahydrocortisol plus 5 alpha-tetrahydrocortisol/tetrahydrocortisone was 6.7-33, whereas the normal ratio is 1.0. Infusion of [11-3H]cortisol resulted in little release of tritiated water, indicating the failure of the conversion of cortisol to cortisone. Thirteen mutations in the HSD11B2 gene have been previously published, and we report three new genetic mutations in two patients, one of whom was previously unreported. All of the patients had homozygous defects except one, who was a compound heterozygote. Our first case had one of the most severe mutations, resulting in the truncation of the enzyme 11 beta HSD2, and died at the age of 16 yr while receiving treatment. Three patients with identical homozygous mutations from different families had varying degrees of severity of clinical and biochemical features. Due to the small number of patients with identical mutations, it is difficult to correlate genotype with phenotype. In some cases, early and vigilant treatment of AME patients may prevent or improve the morbidity and mortality of end-organ damage such as renal or cardiovascular damage and retinopathy. The outcome of treatment in more patients may establish the efficacy of treatment.

Several homozygous mutations in the gene for 11 beta-hydroxysteroid dehydrogenase type 2 in patients with apparent mineralocorticoid excess.

Four deleterious mutations are described in the gene for HSD11B2, which encodes the type 2 isoenzyme of 11 beta-hydroxysteroid dehydrogenase (11 beta HSD2). In seven families with one or more members affected by apparent mineralocorticoid excess, this disorder is shown to be the result of a deficiency in 11 beta HSD2. Surprisingly, the patients are all homozygous for their mutation. This results from consanguinity in two families and possibly from endogamy or a founder effect in four of the other five families. The absence of compound heterozygotes remains to be investigated.

A mutation in the HSD11B2 gene in a family with apparent mineralocorticoid excess.

A mutation in the HSD11B2 gene has been discovered in a consanguineous Iranian family with three sibs suffering from Apparent Mineralocorticoid Excess (AME). Sequence data demonstrate a C to T transition resulting in an R337C mutation.

Complete testicular feminization caused by an amino-terminal truncation of the androgen receptor with downstream initiation.

We have characterized the molecular defect causing androgen resistance in two 46,XY siblings with complete testicular feminization. Although binding studies in genital skin fibroblasts showed a reduced Bmax, an increased dissociation rate of ligand, and an 8S peak of dihydrotestosterone binding on sucrose density gradient centrifugation, no immunoreactive androgen receptor (AR) was detected in immunoblots using anti-NH2-terminal antibodies, suggesting an abnormal amino terminus. Sequence analysis of the AR gene revealed a point mutation CAG-->TAG (Gln-->Stop) at nucleotide 340. In vitro mutagenesis studies suggest the synthesis of the mutant AR is initiated downstream of the termination codon at reduced levels and that each molecule is functionally impaired. These results define a novel mechanism causing androgen resistance: the combination of decreased amount and functional impairment of AR caused by an abnormality within the amino terminus of the receptor. These findings suggest that domains important to the in vivo function of the receptor reside within the amino terminus and that disruption of these domains can occur with only subtle effects on receptor binding. Identification of this mutation made it possible to identify the mutant allele within the family and to ascertain antenatally that it was not present in a 46,XY fetal sibling of the proband at 9 wk gestation.

Anti-Müllerian hormone in three intersex conditions.

Anti-Müllerian hormone (AMH), secreted by embryonic testicular Sertoli cells, inhibits the development of Müllerian ducts in the male. An enzyme-linked immunoassay (ELISA) for AMH was used to investigate three intersex infants. The AMH level was correlated with each patient's degree of Müllerian duct development. Complete inhibition of Müllerian structures correlated with the normal levels of AMH in the infant with testicular feminization. Detectable levels of AMH were found in the hermaphroditic infant; however, these low levels reflected Sertoli cell inadequacy of the ovotestis, which was documented by a right rudimentary Fallopian tube and a normal uterus. In the infant with persistent Müllerian duct syndrome, (PMDS), the normal Müllerian derivatives are compatible with 1) an AMH receptor defect; 2) a biologically and immunologically abnormal AMH molecule, or 3) a functional AMH deletion. The lack of detectable AMH in this infant excluded the AMH receptor abnormality and thus directed authors' search for the specific defect to the AMH gene. Thus, this ELISA for AMH is as valuable a tool to the molecular biologist studying a precise genetic error as it is to the physician making a precise clinical diagnosis.

Permissive action of growth hormone on the renal response to dietary phosphorus deprivation.

Animal studies have shown that GH is necessary for the increased renal production of calcitriol during dietary phosphorus deprivation (PD). These studies suggest that this adaptive change in vitamin D metabolism is mediated through insulin-like growth factor-I (IGF-I) and/or insulin. We subjected 16 GH-deficient children to 96 h of severe dietary PD twice, first before and again during recombinant GH replacement. Half of the children received low dose and half received high dose replacement with recombinant GH. We measured renal tubular reabsorption maximum for phosphate corrected for glomerular filtration rate (TmP/GFR), PTH, IGF-I, calcidiol, and calcitriol pre- and postdietary PD, both off and on GH. We also assessed insulin secretion during an oral glucose load (OGTT) off and on GH. Basal PTH, calcidiol, calcitriol, and fasting blood sugar were unaffected by GH therapy. PD did not affect PTH or calcidiol either off or on GH. Basal TmP/GFR rose on GH therapy (4.8 +/- 0.2 to 6.3 +/- 0.4 mg/dL) and with PD (4.8 +/- 0.2 to 5.7 +/- 0.2 mg/dL off and 6.3 +/- 0.4 to 7.8 +/- 0.3 mg/dL on GH). The increments due to PD and GH therapy were additive. The increments on GH were independent of the GH dose. Before GH replacement, calcitriol did not rise during PD (22.3 +/- 2.1 to 23.3 +/- 1.9 pg/mL), but during GH therapy, PD caused a significant rise in calcitriol (23.8 +/- 2.5 to 33.3 +/- 2.4 pg/mL; P less than 0.0001). The increment in calcitriol during PD was significantly greater in the high dose than it was in the low dose group (11.7 +/- 1.5 vs. 7.2 +/- 1.6 pg/mL; P less than 0.05). GH therapy caused a rise in the IGF-I level that was significantly greater in the high dose (0.26 +/- 0.03 to 3.15 +/- 0.56 U/mL) than in the low dose (0.27 +/- 0.02 to 0.68 +/- 0.13 U/mL) group. Insulin in response to OGTT was significantly greater after GH therapy (4155 +/- 600 microU/mL.min off GH; 6504 +/- 1153 microU/mL.min on GH), although there was no difference between the low and high dose groups. Regression analysis demonstrated a correlation between the change in calcitriol during PD and the IGF-I level (r = 0.83). There was no correlation between insulin levels and the change in calcitriol or between IGF-I or insulin levels and the increment in TmP/GFR during GH therapy.(ABSTRACT TRUNCATED AT 400 WORDS)