Conference Proceedings: Genetic and Hormonal Basis of Sexual Differentiation Disorders: CLINICAL NOTE

Objectives: to document long-term medical, surgical and psychosexual outcome of individuals with congenital micropenis (13 males, 5 females). Methods: Physical measurements from childhood were collected retrospectively from medical records and at adulthood by physical examination. An adult psychosexual assessment was conducted with a written questionnaire and oral discussion. Results: Adult penile length was below the normal mean in all men. Three women had vaginoplasty resulting in normal length. All men reported good or fair erections but 50% were dissatisfied with their genitalia. Dissatisfaction with body image resulted from having a small penis (66%), inadequate body hair (50%), gynecomastia (33%) and youthful appearance (33%). Ten men were heterosexual, 1 homosexual and 2 bisexual. Among women, 4 (80%) were dissatisfied with their genitalia. Three women reported average libido with orgasm and were also heterosexual. Two women had no sexual interest or experience. Finally, males were masculine and females feminine in their gender-role identity, and both groups were satisfied with their sex of rearing. Conclusions: Regarding choice of gender, male sex of rearing can result in satisfactory genito-sexual function. Female gender can also result in success, however it requires extensive feminizing surgery.

Familial isolated GH deficiency type II is an autosomal dominant form of short stature, associated in some families with mutations that result in missplicing to produce del32-71-GH, a protein that cannot fold normally. The mechanism by which this mutant suppresses the secretion of wild-type GH encoded by the normal allele is not known. Coexpression of del32-71-GH with wild-type human GH in transient transfections of the neuroendocrine cell lines GH4C1 and AtT20 suppressed accumulation of wild-type GH. The suppression of wild-type GH accumulation by del32-71-GH was a posttranslational effect on wild-type GH caused by decreased stability, rather than decreased synthesis, of wild-type GH. Coexpression of del32-71-GH with human PRL did not suppress accumulation of PRL, indicating that there was not a general suppression of secretory pathway function. Accumulation of del32-71-GH protein was not necessary for the suppression of wild-type GH, because del32-71-GH did not accumulate in the neuroendocrine cell lines in which suppression of accumulation of wild-type GH was observed. Del32-71-GH did accumulate in transfected COS and CHO cells, but did not suppress the accumulation of wild-type GH in these cells. These studies suggest that del32-71-GH may cause GH deficiency in somatotropes of heterozygotes expressing both wild-type and del32-71-GH by decreasing the intracellular stability of wild-type GH.

Short-term administration of human growth hormone to children with idiopathic short stature can improve mean growth rate and predicted adult height. It is yet unknown whether therapy would alter pubertal development or affect final height. Three-year treatment results in a group of children with idiopathic short stature are reported. For year 1 of the study, 121 prepubertal children were randomly selected to receive somatropin, 0.3 mg/kg per week, administered subcutaneously three times weekly (n = 63), or to be nontreatment control subjects (n = 58). After 1 year, all subjects were again randomly selected to receive either three-times-weekly or daily dosing at the same total dose. For the 92 subjects who completed 36 months of treatment, mean growth rate increased from a mean of 4.6 cm/yr before treatment to a mean of 8.0 cm/yr in the first year of treatment. Daily dosing resulted in a significantly faster mean growth rate (9.0 cm/yr) than three-times-weekly dosing (7.8 cm/yr) (p = 0.0005). Mean growth rates were 7.6 and 7.2 cm/yr during years 2 and 3, respectively, and did not differ by dosing group. Mean standardized height for all subjects improved from -2.7 to -1.6 after 3 years. When the growth rate was standardized for bone age, however, subjects who remained prepubertal had a significantly greater gain in mean height SD score than subjects who became pubertal during that 3-year period (p <0.02). Mean standardized Bayley-Pinneau predicted adult height SD score increased from -2.7 to -1.6 and was independent of the timing of pubertal onset, but for individuals this score was more variable. Year-1 growth response, expressed as growth rate or change in height SD score, was the best predictor of growth in subsequent years. Responses to therapy could not be reliably predicted from baseline anthropometric variables, plasma insulin-like growth factor I SD score, growth hormone levels. Final height assessment will be needed to determine the ultimate benefit of therapy.

Thirty-six former human growth hormone (hGH) recipients underwent comprehensive physical, endocrine and lipoprotein evaluations as adults. Treatment was associated with a decrease in height standard deviation score (SDS) in males from 4.0 pretreatment to 2.1 as adults, and in females from 4.2 to 2.5. Males showed a better growth response to treatment than did females. Plasma somatomedin-C levels were subnormal in 30 patients, but were higher in isolated growth-hormone-deficient patients than in others. Three men and 1 woman showed evidence suggesting a disturbance in pulsatile gonadotropin release despite the previous documentation of normal serum gonadotropin levels. Hypertriglyceridemia was not observed, and the women's plasma cholesterol levels were unremarkable. Men, however, showed higher-than-expected total cholesterol, LDL-cholesterol, and HDL-cholesterol concentrations. The last finding may explain the lack of increased cardiovascular morbidity in this group.

Thirty-six children with growth hormone deficiency were treated for up to 48 months with methionyl human growth hormone (hGH) synthesised by DNA recombinant methods. The growth rate for these children increased from 3·2±1·1 cm/yr to 10 · 5±2·2 cm/yr (mean±SD). This was similar to the effect of pituitary hGH in ten GH deficient children, 3·8±1·0 to 10·1±1·1 cm/yr. Serum somatomedin C rose from 0·26±0·23 U/ml to 0·79±0·53 U/ml after 6 months of methionyl-hGH therapy, similar to the effect of pituitary hGH. The incidence of antibody formation to methionyl-hGH was higher than that observed with pituitary hGH (Kabi) but poor growth was observed only in the one patient on methionyl-hGH who acquired high-titre high-binding-capacity antibodies to hGH. No consistent changes in levels of antibodies to Escherichia coli proteins were detected. No other allergic manifestations or systemic side-effects were demonstrable.

Short stature is less likely to have an endocrine basis than is commonly thought. Any of a number of chronic systemic diseases can slow growth, short stature may result from a genetic tendency or disorder, growth may be constitutionally delayed, or it may be retarded by intrauterine influences. True endocrine causes include thyroid or adrenal disorder, growth hormone deficiency, and psychosocial dwarfism. Although growth hormone deficiency is quite rare, it has received increased attention recently. The capability to produce human growth hormone by recombinant DNA techniques presents the prospect that replacement therapy will be more readily available to those patients who might benefit from it. Caution is called for, however, in making use of this agent for patients other than those with proven growth hormone deficiency.

A patient with clinical features of Turner syndrome and a 45, X karyotype in repeated blood cultures was re‐evaluated when she spontaneously entered puberty. A ring X cell line was found in a small proportion of fibroblasts. A review of 35 previously published ring X cases is presented. All are mosaic, the major cell line in most cases being 45, X. There is wide variation in the frequency with which the abnormalities associated with Turner syndrome are found in these patients. All have short stature. Some are sexually developed and fertile. Cardiovascular anomalies are uncommon. This phenotypic variation may have at least two causes: the size of the deleted portion at each end of the X chromosome, and the relative frequency and distribution of 45, X and 46, X, r(X) cell lines in various body tissues.

Children with growth failure, normal growth hormone responses to stimulation tests, and low somatomedin levels are being recognized with increasing frequency. Sixteen patients, aged 2 to 17 years, with these findings were studied. When treated with human growth hormone, the mean plasma somatomedin-C levels of these patients increased from 0.19 +/- 0.05 (SD) U/mL to 2.29 +/- 1.11 U/mL (P less than .001) and mean growth velocity increased from 3.6 +/- 1.6 (SD) cm/yr to 7.4 +/- 2.9 cm/yr at 8 months of treatment (P less than .001). The effect of human growth hormone therapy on the whole group was statistically significant, but the effect on individuals was highly variable. There was no correlation between magnitude of the increase in somatomedin-C and growth response (r = .26, NS). Thus, the long-term growth-promoting effect of human growth hormone therapy in this group of patients could not be predicted from the magnitude of the somatomedin-C responses.

Hypertension has only recently been reported in neonatal hyperthyroidism. We describe three children with hypertension as a prominent part of the syndrome. Antihypertensive therapy alone was ineffective in controlling elevated BP. All patients showed gradual resolution of hypertension once a euthyroid state was achieved.

Eight patients with established insulin-dependent diabetes mellitus were studied before and 2 weeks after the initiation of pumped continuous sc insulin infusion in order to investigate the effect of short term improvement of glycemic control on hormonal and lipid levels. Glycemic control was improved in all patients. Using a constant blood withdrawal pump, accurate 24-h average concentrations, denoted integrated concentrations, were obtained. The mean 24-h integrated concentrations of GH, cortisol, norepinephrine, and epinephrine did not change significantly. The mean fasting triglyceride concentration dropped from 119.1 to 83.4 mg/dl (P less than 0.05). The mean 24-h integrated concentration of plasma triglycerides fell from 132.1 to 101.5 mg/dl (P less than 0.02). Both mean fasting and mean 24-h integrated concentrations of plasma cholesterol were lower after improved control. Short term improvement in glycemic control was associated with a reduction in plasma lipid concentrations, but failed to alter mean 24-h integrated concentrations of the measured counterregulatory hormones.

Nuclear DNA from individuals belonging to nine different families in which two sibs were affected with isolated growth hormone deficiency type I were studied by restriction endonuclease analysis. By using 32P-labeled human growth hormone or the homologous human chorionic somatomammotropin complementary DNA (cDNA) sequences as a probe, the growth hormone genes of affected individuals from all families yielded normal restriction patterns. Polymorphic restriction endonuclease sites (HincII and MspI), which are closely linked to the structural gene for growth hormone on chromosome 17, were used as markers in linkage analysis of DNA of family members. Of the nine affected sib pairs two were concordant, three were possibly concordant, and four were discordant for both linked markers. Since only concordant sib pairs would have inherited the same growth hormone alleles, further studies to identify mutations of the growth hormone genes should be limited to this subgroup. It is unlikely that the discordance observed in four of the sib pairs is due to recombination, because the polymorphic HincII site is only 116 base-pairs from the -26 codon of the growth hormone gene. Thus, in at least four of the nine families, the mutation responsible for isolated growth hormone deficiency is not within or near the structural gene for growth hormone on chromosome 17.

We have studied DNAs from 8 individuals whose clinical findings and pedigrees were consistent with familial isolated growth hormone deficiency (IGHD). Nuclear DNA was prepared from leukocytes, digested with various restriction endonucleases, subjected to electrophoresis, Southern transferred, and hybridized to 32P-labeled growth hormone (GH) DNA sequences. Restriction patterns of samples from affected individuals in 3 different families with IGHD Type I (autosomal recessive) and 1 family with IGHD Type II (autosomal dominant) were normal; i.e., GH genes were present. Two common polymorphic restriction sites were detected in DNAs of various family members which could be used in linkage analyses. DNA from an individual with IGHD Type IA (autosomal recessive) yielded abnormal patterns following Bgl II, Eco RI plus Bam HI, Hinc II, Pst I, and Sst I digestion. In each digest, one or more fragments (∼2.2 to ∼3.3 kilobases) were absent. These findings suggest that some inactive GH genes are associated with deletions of GH or GH-like sequences.

Nuclear DNA from four individuals with familial isolated growth hormone (somatotropin) deficiency (IGHD) type A was studied by restriction endonuclease analysis. By using 32P-labeled human growth hormone (hGH) cDNA sequences as a probe, patterns seen after various digestions indicated that these individuals were homozygous for a deletion of at least 7.5 kilobases (kb) of DNA. This deletion includes the gene that encodes the normal growth hormone but does not include the variant growth hormone gene. Restriction patterns of DNAs from all family members agreed with an autosomal recessive mode of inheritance of the deletion that correlates with the clinical phenotype. Furthermore, independent assortment of the two types of hGH genes suggests that these genes are nonallelic. These findings indicate that, in these families, IGHD type A is caused by deletion of the normal hGH genes and that this disorder can occur in the presence of variant hGH genes.

Macrosomia in association with a hyperinsulinemic intrauterine environment is found in the fetus of the diabetic mother. We have studied the ovine fetus to demonstrate directly that exogenous insulin administration accelerates fetal growth. Seven mixed breed ewes with radiologically confirmed, nondiscordent twin fetuses were used. Insulin was infused at 90±50 mu/kg/day to one randomly selected fetus while the other twin was infused with saline as control. Infusion was continued for 14.9±1.5 days during which there were no differences in serum glucose, PO2, PCO2, pH or hematocrit between infused and control fetuses. Studies of insulin binding to erythrocyte receptors revealed no differences in maximum percentage binding, mean empty site binding affinity, receptor concentration or the concentration of insulin which inhibited (125I) iodoinsulin by 50%. Following infusion, analysis of fetal growth demonstrated no differences in weight, length or organ weights between control and experimental animals. No effects of insulin infusion were found on tissue water, protein, RNA, DNA or glycogen. We have demonstrated that small amounts of exogenous insulin do not alter the normal pattern or rate of ovine intrauterine growth over a 15 day infusion period. It is possible that insulin at physiologic concentrations has little role in the regulation of fetal growth.

The ontogeny of insulin binding in the sheep was studied using the erythrocytes (RBCs) of 31 fetuses, 10 lambs, and 5 adult animals. Six fetuses were studied on three occasions over a 2-week period from 120--135 days of gestation to provide longitudinal data on changes in insulin binding. Maximal percent binding of [125I]iodoinsulin and receptor concentration decreased significantly as the age of the animal increased (r = 0.76, P less than 0.001 and r = --0.49, P less than 0.001, respectively). Total loss of insulin binding to RBCs was estimated to occur in the second postnatal month, and the RBCs from the adult sheep showed no specific insulin binding. The osmotic fragility of RBCs in each developmental group of animals was also studied to assess possible differences in RBC membrane properties. RBC osmotic fragility was significantly lower in fetuses than in adult sheep (osmotic fragility 50 = 0.55% phosphate-buffered saline vs. 0.76% phosphate-buffered saline, respectively; P less than 0.001). The data suggest that fetal RBCs of lower osmotic fragility and high insulin binding capacity are progressively replaced during late prenatal and early postnatal life by adult-type RBCs of increased osmotic fragility and lacking binding capacity for insulin. The timing of the disappearance of insulin binding to RBCs coincides with the final transition in the animals from a monogastric to a ruminant metabolic state, and may reflect a change in the need for insulin with age.