Takashi Kamijo

Mutations in intron 3 of GH-1 gene associated with isolated GH deficiency type II in three Japanese families

Isolated GH deficiency (IGHD) type II is a disorder inherited in an autosomal dominant manner. Three mutations at the donor splice site of intron 3 of the GH‐I gene have been identified in five families. In this report, we describe a novel mutation also at the donor splice site of intron 3 in patients with IGHD type II.

Screening for growth hormone gene deletions in patients with isolated growth hormone deficiency

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Hereditary isolated growth hormone deficiency caused by GH1 gene mutations in Japanese patients

Most patients with hereditary isolated growth hormone deficiency (IGHD) are either heterozygous or homozygous for a growth hormone (GH) gene abnormality. GH1 gene deletions (6.7 and 7.6 kb) from eight Japanese families with IGHD type IA has been detected by Southern blot analysis or polymerase chain reaction and Smal digestion. Heterozygous point mutations at the donor splice site of intron 3 in the GH1 gene have been identified among autosomal dominant IGHD type II patients. Recently, we have identified two kinds of splicing mutations in intron 3 in four Japanese families with IGHD type II. We believe a newly diagnosed G to A mutation at the fifth base of intron 3 in a Japanese family is responsible for the IGHD type II phenotype.

Growth hormone releasing hormone receptor (GHRH-R) gene mutation in indian children with familial isolated growth hormone deficiency : A study from western India

BACKGROUND Various mutations of the growth hormone releasing hormone receptor (GHRH-R) gene have been recently described to cause familial isolated growth hormone (GH) deficiency (FIGHD), with the GHRH-R nonsense mutation E72X reported in patients with FIGHD from South Asia. The molecular genetic basis of FIGHD in Indian children is not known. OBJECTIVE To look for the GHRH-R E72X non-sense mutation in our patients with FIGHD and describe its clinical phenotype. PATIENTS AND METHOD A total of 31 patients from 22 families diagnosed 4-20 years previously, 20 patients with familial IGHD-IB from 11 families and 11 patients with non-familial isolated GH deficiency (NFIGHD) (phenotypes IGHD-IB in eight patients and -IA in three) were included. Twenty-eight of 31 patients with IGHD-IB came from two states of Western India, 27 of them Hindus from 18 families (three consanguineous) and one from an inbred Moslem kindred. RESULTS Twenty-two of the patients (71%) (18 FIGHD and four NFIGHD) had a homozygous G-->T transversion in exon 3, with this GHRH-R gene mutation E72X in 90% (18/20) of patients with FIGHD, 36% (4/11) of NFIGHD, altogether 78% (22/28) with phenotype IB. One parent pair with IGHD had homozygous E72X mutation, the rest were heterozygous carriers. Two siblings with IGHD due to homozygous E72X mutation were also heterozygous carriers for GH-1 gene 6.7 kb deletion, inherited from their mother, heterozygous for both GH-1 and GHRH-R mutations. Initial chronological age was 10.89 +/- 3.69 years, bone age 6.4 +/- 3.4 years, and mean height SDS was -5.83 +/- 1.41. The clinical phenotype, with sharp features, lean habitus, lack of frontal bossing or hypoglycemia, was characteristic. The mean peak GH was 1.25 +/- 0.75 ng/ml, IGF-I and IGFBP-3 below -2 SDS with no response to GHRH in those tested. MRI (n = 10) showed pituitary hypoplasia, mean vertical height 2.61 +/- 0.76 mm. Among the other 7/11 NFIGHD patients, four with phenotype IB were negative for genotypes tested in this study; of three patients with phenotype IA, two had the GH-1 gene 6.7 kb deletion, and one was a compound heterozygote with 6.7 and 7.6 kb deletions. CONCLUSIONS The majority of patients with FIGHD from different communities belonged to non-consanguineous Hindu families from Western India. The GHRH-R gene E72X mutation was found in 71% of this series, in 90% of FIGHD, 36% of NFIGHD, and in 78% with phenotype IB. The characteristic phenotype helped in suspecting this mutation. GHRH-R gene mutations may be the most reasonable candidate for IGHD-IB with the E72X mutation predominating in the Indian subcontinent. More extensive studies need to be undertaken.

A Japanese family with autosomal dominant growth hormone deficiency.

Abstract We report a 1-year-old Japanese boy and his father with isolated growth hormone deficiency II. In both cases, a G → A transition of the first base of the donor splice site of intron 3 of the growth hormone-1 gene was detected. All unaffected family members were homozygous normal. Conclusion This is the fourth reported case of autosomal isolated growth hormone deficiency II with a G → A transition. The CG dinucleotide at the exon 3-intron 3 junction of the growth hormone-1 gene appears to be a hot spot for point mutations.

A CASE OF ISOLATED GROWTH HORMONE (GH) DEFICIENCY WITH COMPOUND HETEROZYGOUS ABNORMALITY AT THE GH-1 GENE LOCUS

We report a Japanese boy with IGHD who is a compound heterozygote at the GH-1 gene locus. The patient and his mother were heterozygous for a 6.7 kb deletion of the GH-1 gene. A T-->C transition at position -123, an A-->G transition at position -6 and an A-->T transition at position -1 in the GH-1 promoter region and the addition of AGAA at base 250 in intron I were observed in one allele of the patient and his father. These results demonstrate that familial IGHD is a heterogeneous disease that perturbs different steps in the expression of the GH-1 gene.

Isolated growth hormone deficiency in two siblings because of paternal mosaicism for a mutation in the GH1 gene

Context  Mutations in the GH1 gene have been identified in patients with isolated growth hormone deficiency (IGHD). Mutations causing aberrant splicing of exon 3 of GH1 that have been identified in IGHD are inherited in an autosomal dominant manner, whereas other mutations in GH1 that have been identified in IGHD are inherited in an autosomal recessive manner.

A Highly Sensitive Sandwich Enzyme Immunoassay of Urinary Growth Hormone as a Diagnostic Tool for Growth Hormone Deficiency

A total of 41 children with short stature were studied. Their heights were below 2 SD of the mean heights of Japanese boys and girls of their own age groups. They were divided into three groups according to serum peak G H levels in pharmacological tests: 0 up to 5 ngiml, complete G H deficiency (n = 9) between 5 and 10 ng/ml, partial G H deficiency (n = 5) above 10 ng/ml, normal short stature (n = 27). In each subject, both 24-hour and early morning urine specimens were collected. Urinary G H concentration was determined by a highly sensitive sandwich EIA as described previously (1).

Transgenic mice expressing a mutant human GH gene causing type II IGHD

We identified several mutations in the intron 3 of human growth hormone gene I (hGH-I) in patients with isolated GH deficiency (IGHD) type II characterized by an autosomal dominant trait. The mutations result in exon 3 skipping and generation of 17 Kd mutant GH. To elucidate how the mutation causes dominant trait, transgenic mice expressing a mutant hGH gene (the first guanine to adenine transversion in intron 3: GH-I; IVS3+1: G-A) were produced in C57BL/6 strain. Genotypes of mice were identified by PCR-amplified products of tail snip DNAs. Delivery of the mutant hGH transgene into 76 fertilized eggs resulted in production of two male heterozygous transgenic mice (hGH + / - , the zero filial generation, F0). Since the mating of the transgenic mice with the same strain was unsuccessful, they were outcrossed with CD-I (ICR) strain. Only one mouse gave birth, producing 4 male and 7 female (Fl) harboring the mutant hGH gene in one allele (hGH + / - ). F1 mice were mated again with the wild type ICR strain, generating 82 hGH + / - mice (F2: 51 males and 31 females). To study whether somatotrophs in F2 mice express the mutant hGH gene, RNA extracted from the pituitary was subjected to RT-PCR. It was demonstrated that the F2, hGH + / - mice express the mutant hGH gene, lacking exon 3. Thus, these heterozygous mice were sib-mated to generate homozygous mice (F3). The mating resulted in 27% hGH - / - , 64% hGH + / - and 9% hGH + / + mice, indicating that the transgene was carried stably to the descendants and did not interfere with the reproduction. These mice will be a valuable model to study how type II IGHD develops during the course of development.

Regulation of Growth Hormone Gene Expression by Thyroid Hormone and Growth Hormone‐Releasing Hormone in the Rat Pituitary

Synthesis of growth hormone (GH) is increased by thyroid hormones, which stimulate GH gene transcription. Recently, it has been shown that GH-releasing hormone (GHRH) stimulates GH gene transcription independently of its GH-releasing effect. However, it has not been clarified whether GHRH action on the somatotroph is affected by thyroid hormones. The effect of GHRH on pituitary GH content and GH mRNA was therefore studied in rats of varying thyroid status. Rats were rendered hypothyroid by thyroidectomy, and 4 weeks later various doses of thyroxine were administered by intraperitoneal injection for 7 days. The rats were then subdivided into two groups, and one group received intermittent GHRH (8 pg/day) subcutaneously by osmotic pump for 7 days. Pituitary GH and GH mRNA were studied. In hypothyroid rats, GH content and GH mRNA were not increased by GHRH treatment. In euthyroid rats, however, GHRH significantly increased pituitary GH mRNA. These data indicate that thyroid hormone is required for GHRH stimulation of GH gene transcription.