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J Clin Endocrinol Metab. 2005 Aug;90(8):4679-87. Epub 2005 May 31.

Mutation at cleavage site of insulin-like growth factor receptor in a short-stature child born with intrauterine growth retardation.

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  • 1Division of Pediatrics and Perinatology, Tottori University, 36-1, Nishi-machi, Yonago 683-8504, Japan.

Abstract

CONTEXT:

Mouse knockout models have clearly demonstrated the critical importance of IGF-I and IGF receptor type 1 (IGF-IR) for embryonic growth as well as postnatal growth.

OBJECTIVE:

We hypothesized that mutations of IGF-IR gene might predispose to short stature in children born with intrauterine growth retardation (IUGR).

PATIENTS:

Twenty-four children with unexplained IUGR (birth weight < -1.5 SD) and short stature (<-2.0 SD) were screened for abnormalities of the IGF-IR gene.

METHODS:

Direct DNA sequencing was used to identify IGF-IR gene mutations. Unprocessed IGF-IR proreceptor in fibroblasts was detected by immunoblot analysis. Functions of mutated IGF-IR in fibroblasts were evaluated by IGF-I binding, and IGF-I-stimulated DNA synthesis and beta-subunit autophosphorylation.

RESULTS:

We found the following results: 1) a heterozygous mutation (R709Q) changing the cleavage site from Arg-Lys-Arg-Arg to Arg-Lys-Gln-Arg was identified in a 6-yr-old Japanese girl (case 1) and her mother who also had IUGR with short stature (case 2); 2) fibroblasts from case 2 contained more IGF-IR proreceptor protein (189 +/- 26% of normal) and less mature beta-subunit protein (63 +/- 12%); 3) [125I]IGF-I binding to fibroblasts from case 2 was reduced, compared with normal control (0.61 +/- 0.16 x 10(6) vs. 1.14 +/- 0.12 x 10(6) sites per cell; P < 0.05); and 4) both IGF-I-stimulated [3H]thymidine incorporation and IGF-IR beta-subunit autophosphorylation were low in fibroblasts from case 2, compared with those of control (P < 0.05).

CONCLUSIONS:

These findings strongly suggest that this mutation leads to failure of processing of the IGF-IR proreceptor to mature IGF-IR and causes short stature and IUGR.

PMID:
15928254
[PubMed - indexed for MEDLINE]
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