先天性软骨发育不全成纤维细胞生长因子受体3基因1138位核苷酸点突变的检测

目的 验证成纤维细胞生长因子受体3(fibroblast growth factor receptor 3，FGFR3)跨膜区1138位核苷酸为先天性软骨发育不全突变热点及用变性梯度电泳方法筛查的效果。方法 对17例临床诊断为先天性软骨发育不全患者进行基因组DNA聚合酶链反应－限制性酶切片段长度多态性（polymerase chain reaction-restriction fragment length polymorphism,PCR-RFLP)分析，并用变性梯度凝胶电泳（denaturing gradient gel electrophoresis,DGGE)进行其它突变位点的筛查。结果 17例患者中14例RFLP检测显示能被Sfc I酶切，提示存在1138位核苷酸G→A的转换，且均为杂合子。17例用Msp I酶切均阴性，提示无G→C的颠换。DGGE方法的筛查中，酶切阳性的14例标本均显示存在杂合型突变。3例PCR－RFLP检测阴性的标本未显示突变位点，提示在该扩增区域确实不存在突变位点。结论 FGFR3跨膜区1138核苷酸G→A的突变是软骨发育不全的主要发病机理，DGGE可作为筛查某一区域基因突变的敏感而可靠的检测手段，尤其是对杂合子的检测。     

一个软骨发育不全家系成纤维细胞生长因子受体3基因突变分析

目的 基因水平上澄清一个不符合常染色体显性遗传病遗传规律的软骨发育不全家系患者的致病机理。方法 用聚合酶链反应技术扩增家系成员外周血基因组DNA成纤维细胞生长因子受体3(fibroblast growth factor receptor3，FGFR3)基因第10外显子，DNA序列分析寻找突变位点，然后经限制性内切酶Mae1分析验证。结果 患者外周血基因组DNAFGFR3基因第10外显子第1180位核苷酸发现一个A→T新突变，而家系正常成员包括先证者父母不存在此突变。结论 结合系谱分析，这一新突变可能是导致该家系患者软骨发育不全的原因。     

Predominance of the mutation at 1138 of the cDNA for the fibroblast growth factor receptor 3 in Japanese patients with achondroplasia

Summary Fibroblast growth factor receptor 3 (FGFR3) has recently been identified as a putative gene for achondroplasia. Since a guanine to adenine mutation at 1138 of the cDNA for FGFR3 had been identified in most of the patients in Western population, we examined 13 Japanese patients to see if they also share the same mutation. Specific endonuclease digestion of the amplified coding sequence for the transmembrane domain of the FGFR3 revealed that the 12 patients have the G to A change at 1138, while the other had the G to C substitution at the same point, both of which result in G380A substitution. As far as we studied, the homogeneity of the point mutation at 1138 is also authentic to Japanese patient as well as Western patients.     

Common mutations in the fibroblast growth factor receptor 3 (FGFR3) gene account for achondroplasia,hypochondroplasia, and thanatophoric dwarfism

The mapping of the achondroplasia locus to the short arm of chromosome 4 and the subsequent identification of a recurrent missense mutation (G380R) in the fibroblast growth factor receptor 3 (FGFR-3) gene has been followed by the detection of common FGFR-3 mutations in two clinically related disorders: thanatophoric dwarfism (types I and II) and hypochondroplasia. The relative clinical homogeneity of achondroplasia was substantiated by demonstration of its genetic homogeneity as more than 98% of all patients hitherto reported exhibit mutations in the transmembrane receptor domain. Although most hypochondroplasia cases were accounted for by a recurrent missense substitution (N540K) in the first tyrosine kinase (TK 1) domain of the receptor, a significant proportion (40%) of our patients did not harbor the N540K mutation and three hypochondroplasia families were not linked to the FGFR-3 locus, thus supporting clinical heterogeneity of this condition. In thanatophoric dwarfism (TD), a recurrent FGFR-3 mutation located in the second tyrosine kinase (TK 2) domain of the receptor was originally detected in 100% of TD II cases, our series seven distinct mutations in three different protein domains were identified in 25 of 26 TD I patients, suggesting that TD, like achondroplasia, is a genetically homogenous skeletal disorder. © 1996 Wiley-Liss, Inc.     

A novel missense mutation Ile538Val in the fibroblast growth factor receptor 3 in hypochondroplasia

Hypochondroplasia and achondroplasia are skeletal dysplasias, characterised by autosomal dominant inheritance and disproportionate short stature, which occurs mainly due to growth failure of the extremities. Both dysplasias have been mapped to fibroblast growth factor receptor 3 (FGFR3) gene. For hypochondroplasia, two point mutations, both responsible for the Asn540Lys substitution in the region coding the tyrosine kinase domain have been reported. Here we report an A to G transition at position 1651, predicting an Ile538Val substitution in the FGFR3, in hypochondroplasia. The substitution is found in a swedish family with three affected members. The criteria for hypochondroplasia were disproportionate short stature and radiological evidence of shortened long bones and decrease or absence of normal increase in interpedicular distances of the lumbar column. The mutation was detected by direct sequencing and restriction enzyme Tai I digestion. The base change was not found in the FGFR3 genes of unaffected members of the family nor in seventy-five unrelated unaffected individuals, suggesting that it was not a polymorphism. The Ile538Val substitution is a conservative amino acid change (a hydrophobic amino acid incorporated for another hydrophobic amino acid). Nevertheless, it is located in the stretch of nine amino acids, which is highly conserved among all the human fibroblast growth factor receptors. Considering the location of this substitution and the segregation with the phenotype in this family, we propose that it is a causative mutation of hypochondroplasia. It is difficult to establish whether the Ile538Val substitution is rare in hypochondroplasia patients or whether the individuals, who have a moderate degree of short stature, rarely seek medical help for the short stature and consequently are rarely diagnosed as affected by hypochondroplasia. Hum Mutat 11:333, 1998. © 1998 Wiley-Liss, Inc.     

Expression of acidic fibroblast growth factor (aFGF) and fibroblast growth factor receptor 4 (FGFR4) in breast fibroadenomas

BACKGROUND/AIM: Fibroadenomas are benign tumours composed of both glandular and fibrous tissue. The mechanisms regulating the growth of these tumours and the relation between the stromal and epithelial cells are poorly understood. Acidic fibroblast growth factor (aFGF) is a well known fibroblast activator, which acts through four specific cell surface receptors, among which, fibroblast growth factor receptor 4 (FGFR4) is highly specific. The aim of this study was to evaluate the distribution of aFGF and FGFR4 in specific cell types of fibroadenomas to understand their possible role in the growth of these breast lesions. METHODS: Formalin fixed and paraffin wax embedded tissues from 15 fibroadenomas and peritumoral normal breasts were investigated for the expression of aFGF and FGFR4 using immunohistochemistry. The presence of aFGF mRNA was also investigated using in situ hybridisation. RESULTS: Immunoreactivity for aFGF and FGFR4 was seen in epithelial cells, but it was lacking in myoepithelial cells of both normal tissues and fibroadenomas. Strong FGFR4 immunoreactivity was found in stromal fibroblasts, which were also weakly positive for aFGF. aFGF mRNA was detected in epithelial cells and in some stromal fibroblasts. CONCLUSIONS: These results suggest a paracrine/autocrine modulation of epithelial and stromal cells of fibroadenomas through an aFGF-FGFR4 interaction. This interaction might regulate various cell functions and the growth of fibroadenomas.     

The first Korean case of Beare-Stevenson syndrome with a Tyr375Cys mutation in the fibroblast growth factor receptor 2 gene

Here we report the first case of a Korean infant with a cloverleaf-shaped craniosynostosis, in which the diagnosis of Beare-Stevenson syndrome was suspected upon observation of the typical morphological features. This infant exhibited craniofacial anomalies, ocular proptosis, cutis gyrata, acanthosis nigricans, prominent umbilical stump, furrowed palms and soles, hypospadia, and sacral skin tag coupled with dermal sinus tract. Brain magnetic resonance imaging revealed that the patient also had non-communicating hydrocephalus with Chiari malformation. This is the 8th report of Beare-Stevenson syndrome in the literature, which was confirmed by the detection of a Tyr375Cys mutation in the fibroblast growth factor receptor 2 (FGFR2) gene.     

Phenotypic expression of the fibroblast growth factor receptor 3 (FGFR3) mutation P250R in a large craniosynostosis family.

The craniosynostosis syndromes are a heterogeneous group of sporadic, autosomal dominant disorders with significant clinical overlap. Recently, we described a large family with autosomal dominant craniosynostosis suggestive of Saethre-Chotzen syndrome, in which linkage to the Saethre-Chotzen syndrome loci on 7p had been excluded. We now report the presence of a mutation in the fibroblast growth factor receptor 3 (FGFR3) in this family. The mutation, P250R, had been previously reported in 10 patients with non-syndromic craniosynostosis. Variable expression of this mutation is evident especially in two additional members of this family, one of whom is severely affected with pancraniosynostosis. The family provides a further example of genetic heterogeneity and variable expression of the craniosynostosis syndromes and broadens the phenotypic spectrum associated with the FGFR3 mutation P250R. In addition, we found a polymorphism (F384L) in the transmembrane domain of FGFR3 which occurs with a frequency of 3% in the Turkish population but is uncommon among Germans.     

Severe achondroplasia with developmental delay and acanthosis nigricans (SADDAN): phenotypic analysis of a new skeletal dysplasia caused by a Lys650Met mutation in fibroblast growth factor receptor 3.

We previously discovered a novel missense mutation (Lys650Met) in the tyrosine kinase domain of the fibroblast growth factor receptor 3 (FGFR3) gene in four unrelated individuals with a condition we called "severe achondroplasia with developmental delay and acanthosis nigricans" (SADDAN) [Tavormina et al., 1999: Am. J. Hum. Genet. 64:722-731]. Here we present a more detailed clinical account of the SADDAN phenotype. The FGFR3 Lys650Met mutation results in severe disturbances in endochondral bone growth that approach and overlap those observed in thanatophoric dysplasia, type I. However, this mutation is most often compatible with survival into adulthood. Other unusual bone deformities, such as femoral bowing with reverse (i.e., posterior apex) tibial and fibular bowing and "ram's horn" bowing of the clavicle, are also seen in some patients. In addition to skeletal dysplasia, progressive acanthosis nigricans, and central nervous system structural anomalies, seizures and severe developmental delays are observed in surviving SADDAN patients. Despite its location within the same FGFR3 codon as the thanatophoric dysplasia type II mutation (Lys650Glu) and a similar effect on constitutive activation of the FGFR3 tyrosine kinase, the Lys650Met is not associated with cloverleaf skull or craniosynostosis.