FISH analysis for apparently simple terminal deletions of the X chromosome: identification of hidden structural abnormalities.

We report on fluorescence in situ hybridization (FISH) analysis in 30 mosaic or nonmosaic females diagnosed as having apparently simple terminal X deletions by standard G-banding analysis. FISH studies for DXZ1, the Xp and Xq telomere regions, and the whole X chromosome painting were carried out for the 30 females, indicating rearranged X chromosomes with signal patterns discordant with terminal deletions in 6 cases: one dic(X)(DXZ1++) chromosome, two der(X)(qtel++) chromosomes, one Xq- (qtel+) chromosome, and two der(X)(ptel++) chromosomes. Additional FISH studies were performed for the 6 cases using probes defining 12 loci on the X chromosome, showing large Xp deletion and small Xp duplication in the dic(X)(DXZ1++) chromosome, partial Xp deletions and partial Xq duplications in the two der(X)(qtel++) chromosomes, an interstitial Xq deletion in the Xq- (qtel+) chromosome, and partial Xq deletions and partial Xp duplications in the two der(X)(ptel++) chromosomes. Clinical assessment of the 6 cases revealed tall and normal stature in the two mosaic cases with the der(X)(ptel++) chromosomes that were shown to be associated with SHOX duplication. The results suggest that unusual X chromosome rearrangements are often misinterpreted as simple terminal X deletions, and that FISH analysis is useful for precise structural determination and better genotype-phenotype correlation of the X chromosome aberrations.

A novel V59E missense mutation in the sodium iodide symporter gene in a family with iodide transport defect.

Iodide transport defect results from the malfunction of iodide transporter (sodium iodide symporter [NIS]), and is characterized by low uptake of iodide into thyroid cells. Genetic analysis revealed that a T354P missense mutation causes iodide transport defect in the homozygous state and is a frequent mutation in the Japanese population. We recently reported three siblings with iodide transport defect harboring the T354P mutation in the heterozygous state. Here we report a novel V59E missense mutation associated with these siblings. The mutant protein showed low iodide transport activity.

When and how to combine growth hormone with a luteinizing hormone-releasing hormone analogue.

The effect of combined treatment with growth hormone (GH) and a luteinizing hormone-releasing hormone (LHRH) analogue, or GH alone, on pubertal height gain was assessed in an uncontrolled study in 15 boys and 10 girls with GH deficiency (GHD). Seven boys and six girls were treated with GH alone (group 1), and eight boys and four girls were treated with a combination of GH and an LHRH analogue during puberty (group 2). Mean ages (+/- SD) at the start of GH treatment and at the onset of puberty were significantly lower in group 2 (8.0 +/- 3.3 years and 11.2 +/- 0.8 years, respectively, in boys, and 6.3 +/- 1.6 years and 10.8 +/- 0.7 years in girls) than in group 1 (12.8 +/- 1.9 years and 13.7 +/- 1.4 years in boys, and 11.2 +/- 1.0 years and 12.5 +/- 1.2 years in girls). Height at the onset of puberty was less in group 2 than in group 1, but the difference was significant only for the boys. Combination treatment was started at a mean age of 11.7 +/- 1.2 years in boys and 11.5 +/- 1.0 years in girls. The duration of the combination treatment was 5.1 +/- 1.5 years in boys and 2.3 +/- 0.7 years in girls. The duration of the period between the onset of puberty and the end of GH treatment was significantly longer in group 2 (6.8 +/- 1.2 years in boys and 5.5 +/- 1.0 years in girls) than in group 1 (4.3 +/- 1.6 years in boys and 3.6 +/- 1.4 years in girls). The pubertal height gain was also significantly greater in group 2 (36.7 +/- 6.5 cm in boys and 29.0 +/- 8.3 cm in girls) than in group 1 (21.9 +/- 4.1 cm in boys and 18.6 +/- 4.1 cm in girls). Final height was significantly greater in group 2 than in group 1 in boys. Although there was no significant difference in final height between groups in the girls, the change in height SDS from the start of GH treatment until final height was significantly greater in group 2 (2.7 +/- 1.6 in boys and 4.5 +/- 0.5 SD in girls) than in group 1 (1.0 +/- 0.8 in boys and 1.8 +/- 0.9 SD in girls), in both boys and girls. In conclusion, it appears that combination of an LHRH analogue and GH may increase the pubertal height gain and the final height of children with GHD. The improvement is attributed to the prolongation of the treatment period, permitting slow bone maturation, and to the maintenance of height velocity. This combination treatment appears to be more effective in boys than girls. To fully assess this therapeutic approach, prospective controlled studies are needed.

Functional characterization of truncated growth hormone (GH) receptor-(1-277) causing partial GH insensitivity syndrome with high GH-binding protein.

We have previously reported a novel heterozygous donor splice site mutation in intron 9 of the GH receptor (GHR) gene in Japanese siblings who showed partial GH insensitivity and high serum GH-binding protein (GHBP) levels. This mutation caused the splicing abnormality and produced the truncated GHR consisting of 277 amino acids (GHR-277), which lacked most of the intracellular domain of GHR, including both boxes 1 and 2. In this study, we have characterized the function of GHR-277 expression in COS-7 and CHO cells in vitro. Scatchard analysis revealed that GHR-277 possessed approximately 1.5 times higher affinity to GH and twice the number of binding sites compared to wild-type full-length GHR (GHR-fl). The GHBP level in culture medium of GHR-277-expressing cells was approximately 3 times higher than that in GHR-fl-expressing cells. Interestingly, the ligand-induced internalization of GHR-277 was significantly reduced compared with that of GHR-fl. Moreover, in GH-induced tyrosine phosphorylation of signal transducer and activator of transcription-5 (STAT5), GHR-277 exerted a dominant negative effect when GHR-277 and GHR-fl were cotransfected. These in vitro data would well explain the clinical characteristics in our patients showing high serum GHBP levels and development of short stature despite a heterozygous mutation of the GHR gene.

Recurrent T354P mutation of the Na+/I- symporter in patients with iodide transport defect.

Iodide transport defect (ITD) is a rare disorder causing congenital hypothyroidism. We previously reported that homozygous T354P mutation in the sodium/iodide symporter (NIS) gene caused ITD. To clarify the prevalence of this mutation, artificial substitution introducing PCR followed by restriction enzyme analysis was developed as a rapid screening method to detect the T354P mutation. Three apparently unrelated families with ITD, one patient with low thyroidal 99mTc pertechnetate (99mTcO4-) uptake and 52 healthy controls (104 alleles) were analyzed for this mutation. All families with ITD harbored the mutation, suggesting that T354P is a recurrent mutation and a major cause of ITD. This was not a widespread mutation, because it was not detected in the 52 unrelated normal controls. Because two cases with homozygous T354P mutation developed multinodular goiters within their second decade of life though they had been maintained in euthyroid state, homozygous T354P mutation alone and/or low intrathyroidal iodide and high serum TSH level in early life might account for tumorigenesis. The patient with low thyroidal 99mTcO4- uptake did not harbor the T354P mutation. Because familial hypocalciuric hypercalcemia was also present in this family, a possibility of the combined abnormality of TSH receptor and calcium functions, which includes an abnormality around the G protein, may be examined further.

Growth hormone (GH) insensitivity syndrome with high serum GH-binding protein levels caused by a heterozygous splice site mutation of the GH receptor gene producing a lack of intracellular domain.

Most of the GH receptor (GHR) gene abnormalities causing GH insensitivity syndrome (GHIS) are located in the region coding the extracellular domain, and serum GH-binding protein (GHBP) levels, determined by ligand-mediated immunofunctional assay, are low in most of the patients with GHIS. We present here a heterozygous point mutation of the donor splice site in intron 9 of the GHR gene in two Japanese siblings with GHIS, whose serum GHBP levels were high. The same mutation was found in their mother as well. The analysis of ribonucleic acid from the peripheral leukocytes revealed complete skipping of exon 9 from one allele, but not the other, in the GHR complementary DNA and appearance of a premature stop codon in exon 10. The translated protein was truncated with deletion of 98% of the intracellular domain of the GHR, including boxes 1 and 2, which are critical for GH signal transduction and GHR internalization, respectively. Recently, it was shown that the truncated GHR lacking the intracellular domain was physiologically present in a minute amount, served as a negative regulator for GH signaling, and possessed increased capacity to generate GHBP. Therefore, the mutation found in our patients caused the pathogenetic production of the truncated GHR with a dominant negative effect on GH signaling, which is probably responsible for their short stature and high serum GHBP levels.

Novel compound heterozygous mutations of growth hormone (GH) receptor gene in a patient with GH insensitivity syndrome.

A girl with severe growth retardation had the clinical features of Laron syndrome. Her serum insulin-like growth factor-I level was completely unresponsive to exogenous GH administration. The serum GH-binding protein (GHBP) level was below the detectable limit in the patient, but it was normal in her parents and brother. Her parents and brother were normal in their height. Amplification with PCR and direct sequencing of her GH receptor gene revealed compound heterozygous mutations. The allele from her mother contained a transversion of G to T in exon 7 that could introduce a stop codon in place of a glutamic acid at amino acid 224. Another mutation was found in the allele in her father and also identified in her brother. It was a C deletion at position 981 in exon 10 that could introduce a frame shift, thereby causing the production of 20 novel amino acids (310-329) instead of the wild-type sequence, the premature termination at codon 330, and the subsequent deletion of the C terminal portion of the intracellular domain. RT-PCR of her father's lymphocytes and sequencing of its complementary DNA revealed that only the wild-type GH receptor messenger RNA was expressed in his lymphocytes, though the mechanism remains unclear. These results suggest that neither of the mutant alleles could generate a functional GH receptor, which would be consistent with the patient's severe growth retardation and undetectable serum GHBP.

Screening for PIT1 abnormality by PCR direct sequencing method.

PIT1 abnormality is defined as a genetic abnormality in the PIT1 gene, which encodes a pituitary specific transcription factor Pit-1/GHF-1.PIT1 abnormality has been reported in several patients displaying either complete or incomplete deficiency of thyrotropin (TSH), growth hormone (GH), and prolactin (PRL) in either familial or sporadic cases. To see if there are abnormalities in the PIT1 gene in patients with incomplete TSH, GH, and PRL deficiency, we utilized a PCR direct sequencing method to determine the Pit-1/GHF-1 coding sequence. A total of 15 patients, 1 patient from a family with TSH and GH deficiency, 3 patients with TSH, GH, and PRL deficiency, and 11 patients treated with both human GH (hGH) and thyroid hormone were studied. In one patient of combined pituitary hormone deficiency, the Arg-271-Trp mutation was detected. Since both of the parents did not harbor this mutation, it is a de novo germ line mutation. No mutation was detected in the other patients, showing that PIT1 abnormality is not a frequent cause of GH deficiency.

Clinical utility of insulin-like growth factor binding protein-3 in the evaluation and treatment of short children with suspected growth hormone deficiency.

We have shown previously that serum insulin-like growth factor binding protein-3 (IGFBP-3) levels have good predictive value for complete, but not partial, growth hormone deficiency (GHD). In this study, we compare IGFBP-3 levels in short children previously divided into groups on the basis of their post-stimulation GH levels. Complete GHD (N = 59) included those children with peak post-stimulation GH < 5 micrograms/l. The partial GHD group (N = 49) had post-stimulation GH peaks of > 5 micrograms/l but < 10 micrograms/l. The normal children with short stature (N = 103) had post-stimulation GH peaks > 10 micrograms/l. Partial GHD and normal children with short stature also were divided into either low IGF-I or normal IGF-I subgroups. The clinical sensitivity of IGFBP-3 for complete GHD was 92%, whereas its sensitivity for partial GHD was 39%. For partial GHD, among those with low IGF-I (N = 19) 68% were also low for IGFBP-3, while 80% of those with normal IGF-I (N = 30) were also normal for IGFBP-3. The clinical specificity of IGFBP-3 for normal children with short stature was 69%. For these groups, among those with low IGF-I (N = 22) 73% also were low for IGFBP-3, while 80% of those with normal IGF-I (N = 81) also were normal for IGFBP-3. In addition, we tested whether IGFBP-3 can predict the response to GH treatment in prepubertal children by comparing pretreatment IGFBP-3 with the height gain achieved by 1 year of GH treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparison between insulin-like growth factor-I (IGF-I) and IGF binding protein-3 (IGFBP-3) measurement in the diagnosis of growth hormone deficiency.

To analyze the utility of insulin-like growth factor-I (IGF-I) and insulin-like growth factor binding protein-3 (IGFBP-3) radioimmunoassay in the diagnosis of growth hormone deficiency (GHD) we measured IGF-I and IGFBP-3 in sera from normal children (n = 309), short children (n = 99) and patients with GHD (n = 73). In 80% and 93% of classical GHD (cGHD), IGF-I and IGFBP-3 levels, respectively, were below the age-related cutoff levels (lower limit). In 81% and 88% of normal short children (NS), IGF-I and IGFBP-3 levels, respectively, were above the age-related cutoff levels. Thus, both IGF-I and IGFBP-3 were good parameters for screening GHD. In contrast, in more than half of partial GHD (pGHD), either IGF-I or IGFBP-3 was above the age-related cutoff levels. The poor discrimination between patients with pGHD and NS by using these two parameters may be the result of their relatively similar GH levels, as compared to cGHD, or due to the limitations of GH stimulation tests. In about 80-90% of NS, IGF-I and IGFBP-3 were above the age-related cutoff levels at all ages. A hundred percent of cGHD under 10 years old had IGFBP-3 below the age-related cutoff levels, whereas 79% of cGHD under 10 years old had IGF-I below the age-related cutoff levels. Thus in the younger age groups, IGFBP-3 may be more sensitive than IGF-I. It may be because IGFBP-3 levels are relatively higher than those of IGF-I in younger subjects.(ABSTRACT TRUNCATED AT 250 WORDS)

Usefulness and limitation of measurement of insulin-like growth factor binding protein-3 (IGFBP-3) for diagnosis of growth hormone deficiency.

To analyze the utility of insulin-like growth factor binding protein-3 (IGFBP-3) radioimmunoassay for diagnosis of growth hormone deficiency (GHD) we measured IGFBP-3 in sera from normal children, short children and patients with GHD. The sensitivity (true positive ratio) of IGFBP-3 for complete GHD (cGHD) was 93%, while the specificity (true negative ratio) for normal short children (NS) was 88%. In contrast, the sensitivity of IGFBP-3 for partial GHD (pGHD) was only 43%. The poor discrimination between patients with pGHD and NS may be the result of their relatively similar GH level, as compared to cGHD, or due to the limitations of GH stimulation tests. The specificity of IGFBP-3 for NS was excellent in children of all ages: less than 10 years old (87%) and older than 10 (88%). However, sensitivity for GHD was good for children less than 10 years old (84%) but poor for children older than 10 (64%). IGFBP-3 may be less sensitive for diagnosing GHD in older children because IGFBP-3 levels may also increase during puberty due to mechanisms independent of the GH-IGF-I axis.

Massive intestinal albumin loss after Fontan operation.

Massive intestinal protein loss was demonstrated and the site of loss determined by abdominal scintigraphy with 99mTc-labeled human serum albumin in a 9-year-old girl following the Fontan operation for pulmonary atresia with intact ventricular septum. Significant activity accumulating in the lower small intestine and moving with its contents into the colon were shown. Her condition may have resulted from intestinal lymphangiectasia, caused by increased central venous pressure. Abdominal scintigraphy with 99mTc-human serum albumin is useful in the diagnosis of protein-losing enteropathy.

The effect of thyroid hormone on the activities of lactase in the culture of fetal rat intestine.

The effects of thyroid hormone on lactase activities were studied in vitro organ culture of fetal rat intestine. Triiodothyronine inhibited lactase activities regardless the presence of dexamethasone. Also triiodothyronine decreased lactase activities when added after dexamethasone increased lactase activities. Our results suggest that thyroid hormone may have a role in the maturational changes of lactase activities during weaning.

Metabolic changes following gastroplasty in Prader-Willi syndrome--a case report.

A vertical banded gastroplasty was performed in an adult female patient with Prader-Willi syndrome in an attempt to prevent the metabolic deterioration caused by polyphagia. After her operation, the patient felt satiated with the scheduled amount of food and one month later, her fasting blood sugar concentration (FBS) decreased from 521 to 125 mg/dl, and her urinary sugar excretion (US) from 257 to 9 g/day. Both glucose tolerance and insulin secretion were also improved. However, these parameters subsequently became worse after dietary control was lost since the surgical procedure alone was unable to continue to suppress the insatiable desire to eat food. Both her glucose tolerance and insulin secretion by the 31st postoperative month were better than before the surgery, but worse than at one month after the surgery. At the end of the surgery, but worse than at one month after the surgery. At the end of the 34th postoperative month, even under the temporary administration of 0.625 mg/day of glibenclamide, her FBS was 158 mg/dl and US, 38.1 g/day. Her body weight had also increased to over her preoperative value. Based on these results, we conclude that the effect of gastroplasty to prevent metabolic deterioration in our patient with Prader-Willi syndrome gradually diminishes.

Prevention of neonatal HBV infection with the combination of HBIG and HBV vaccine and its long-term efficacy in infants born to HBeAg positive HBV carrier mothers.

Seventy-three infants born to HBeAg positive HBV carrier mothers were protected from neonatal HBV infection with our standard prevention schedule consisting of two doses of HBIG (0,2 mo) and three doses of HBV vaccine (2, 3, 5 mo). In 62 infants who successfully responded to HBV vaccine with a titer of anti-HBs greater than 2(3), anti-HBs titer was monitored for as long as 48 months (25.6 +/- 11.0 mo) and found to decrease as follows: 5.1 +/- 1.7 at 12 mo., 4.5 +/- 1.8 at 18 mo., 4.2 +/- 1.8 at 24 mo., 4.0 +/- 1.6 at 30 mo., 3.7 +/- 1.7 at 36 mo., 3.2 +/- 2.0 at 48 mo. During the follow-up period, eight HBV events (11.9%) were demonstrated: one case showed an increase of anti-HBs, three showed a reappearance of anti-HBc alone, three showed a reappearance of anti-HBc with increase of anti-HBs, and one became a chronic HBV carrier. All infants were further divided into three groups by their maximal response of anti-HBs to HBV vaccine: Group I (greater than or equal to 2(6)), Group II (2(3)-2(5)), and Group III (2(2) greater than or equal to). Group I sustained a higher titer from 12 to 30 months of age and had less HBV events than G-II and G-III. Our study suggests that acquisition of a high titer of anti-HBs is important in long-term prevention of HBV infection as well as in the neonatal period in infants born to HBeAg positive HBV carrier mothers.

Transient infantile hyperthyrotrophinaemia.

Sixteen cases of transient infantile hyperthyrotrophinaemia were followed up for two to seven years. Concentrations of serum triiodothyronine, thyroxine, and free thyroxine were maintained within the normal range in all cases. All but one child, who had a hearing disturbance, showed normal mental development with normal physical and skeletal maturation. Eleven children had normal concentrations of serum thyroid stimulating hormone and no signs or symptoms of thyroid dysfunction; in three children, diffuse small goitres developed and two further children showed relapse with slightly raised concentrations of thyroid stimulating hormone. It is concluded that 'transient infantile hyperthyrotrophinaemia' is a syndrome, which differs from typical transient neonatal hypothyroidism, and that careful follow up is necessary because some children show signs of mild pituitary-thyroid dysfunction in later childhood.