Mosaicism in Hartsfield syndrome

Hartsfield syndrome is a rare condition characterised by the co-occurrence of ectrodactyly and holoprosencephaly spectrum disorders; cleft lip and palate is a common associated feature. This is due to either monoallelic, or less commonly, biallelic variants in FGFR1 with a loss of function or dominant negative effect. To date 37 individuals have been reported, including two instances of germline mosaicism. We report a further family with Hartsfield syndrome due to a novel variant in FGFR1, with two affected fetuses, and somatic and germline mosaicism in the father detected on Sanger sequencing. The father had not come to medical attention prior to this finding. In light of our findings and those in the published literature, we suggest that mosaicism, either germline or germline and somatic, may be a relatively frequent finding, affecting 3 of 35 (9%) reported families, which has important implications for genetic counselling.     

FGF10及其受体FGFR1、FGFR2在昆明小鼠输卵管和子宫内的分布

目的观察成纤维细胞生长因子10(FGF10)、成纤维细胞生长因子受体(FGFR1、FGFR2)在昆明小鼠输卵管和子宫内的定位与分布。方法应用免疫组织化学法进行蛋白质定位观察。结果FGF10和FGFR1免疫阳性反应定位于昆明小鼠输卵管上皮细胞,FGFR2的免疫阳性反应见于肌层平滑肌。FGF10和FGFR1免疫阳性反应分布于昆明小鼠子宫内膜上皮、子宫腺上皮和肌层平滑肌,而FGFR2免疫阳性反应见于肌层平滑肌。结论FGF10及其受体在输卵管和子宫的分布可能参与输卵管和子宫的重要功能。     

FGFR2 mutation in a patient with Apert syndrome associated with humeroradial synostosis

ABSTRACT  Most cases of Apert syndrome are due to S252W or P253R mutations in the fibroblast growth factor receptor 2 (FGFR2) gene. Differences in the effects of S252W and P253R mutations on the clinical features of Apert syndrome have been studied, but little is known about the type of FGFR2 mutation in Apert syndrome with humeroradial synostosis. To study a correlation between the FGFR2 mutations and the clinical complications, we examined the FGFR2 gene in a patient with Apert syndrome associated with humeroradial synostosis, and found that the mutation was S252W. This report suggested that S252W mutation in FGFR2 may cause humeroradial synostosis in Apert syndrome.     

Ullrich-Turner syndrome and neurofibromatosis-1

There is a well-known association between neurofibromatosis-1 (NF1) and Noonan syndrome-like manifestations, including short stature, short broad neck, and hypertelorism. These anomalies are thought to be due to variable expression of the NF1 gene. We report on two girls with NF1 who were found to have the Ullrich-Turner syndrome. Case 1, a 12-year-old white girl, was followed in a Neurofibromatosis Clinic because of multiple café-au-lait spots and a family history of NF1 in her mother and sister. On examination, she had short stature, hypertelorism, and short neck with low posterior hairline. Karyotype was 86% 46,XY/14% 45,X. Case 2, the first child of a woman with NF1, presented at birth with lymphedema of hands and feet and a short broad neck. Karyotype was 45,X. At age 23 months she was short, had epicanthic folds, hypertelorism, narrow palate, right simian crease, 19 café-au-lait spots, and axillary freckling. We conclude that chromosome studies should be performed in girls with NF1 who have short stature and Noonan- or Ullrich-Turner-like findings. Dilemmas raised by the dual diagnoses of NF1 and Ullrich-Turner syndrome include potential risks of growth hormone therapy and estrogen replacement therapy. © 1996 Wiley-Liss, Inc.     

FGF10、FGF18及其受体在小鼠卵巢内的定位分布

目的观察成纤维细胞生长因子(FGF10、FGF18)及其受体FGFR1、FGFR2和FGFR3在昆明(KM)小鼠卵巢内的定位与分布。方法应用免疫组织化学法进行定位观察。结果FGF10及其受体FGFR1与FGFR2的免疫阳性反应见于卵母细胞的胞质,此外,FGFR2的阳性反应还见于卵泡膜。卵母细胞和黄体细胞的胞质呈FGF18免疫阳性反应,FGFR3的免疫阳性反应物位于卵母细胞、卵泡细胞和黄体细胞的胞核。结论FGF10、FGF18及其受体在KM小鼠卵巢的分布,可能参与卵泡的生长发育和卵母细胞的成熟。     

Novel FGFR1 sequence variants in Kallmann syndrome, and genetic evidence that the FGFR1c isoform is required in olfactory bulb and palate morphogenesis

In a new cohort of 141 unrelated patients affected by Kallmann syndrome we identified FGFR1 sequence variants in 17 patients, all in the heterozygous state. The fifteen novel variants consist of 10 missense (p.N77K, p.C101F, p.R250W, p.G270D, p.P283R, p.S332C, p.H621R, p.S685F, p.I693F, p.R822C), two nonsense (p.E324X, p.R661X), a frameshift (p.S439fs), and two splice site (c.1081G>C and c.1977+1G>A) changes. However, the p.N77K and p.R822C changes were also found in two and one out of 150 healthy control individuals, respectively, and therefore, their pathogenic effect is questionable. Notably, three alterations (p.E324X, p.S332C, c.1081G>C) are located in the alternative exon 8B that codes for the FGFR1c isoform, thus indicating that this isoform plays a crucial role in the development of the olfactory system in man. Moreover, the presence of cleft palate in a patient carrying the p.E324X change shows that FGFR1c is important for palate morphogenesis too.     

Subtle radiographic findings of achondroplasia in patients with Crouzon syndrome with acanthosis nigricans due to an Ala391Glu substitution in FGFR3

A unique type of craniofacial dysostosis, Crouzon syndrome with acanthosis nigricans (CAN), has been attributed to a specific substitution (Ala391Glu) in the fibroblast growth factor receptor 3 (FGFR3) gene. At birth, individuals with this disorder have craniosynostosis, ocular proptosis, midface hypoplasia, choanal atresia, hydrocephalus, and they experience the onset of acanthosis nigricans during childhood. We report three cases and compare the clinical characteristics of our cases with the previously reported cases of this disorder. Since the Ala391Glu substitution in FGFR3 is close to the substitutions in the transmembrane domain that result in achondroplasia, we carefully reviewed the skeletal findings in six patients. We identified subtle radiographic findings of achondroplasia in all six cases including narrow sacrosciatic notches, short vertebral bodies, lack of the normal increase in interpediculate distance from the upper lumbar vertebrae caudally, and broad, short metacarpals and phalanges. Even before acanthosis nigricans appears, the presence of choanal atresia and hydrocephalus in an individual with features of Crouzon syndrome should suggest the diagnosis of CAN, and subtle skeletal findings can lend further support to this diagnosis. © 2001 Wiley‐Liss, Inc.     

New missense variants in RELT causing hypomineralised amelogenesis imperfecta

Amelogenesis imperfecta (AI) is a heterogeneous group of genetic diseases characterised by dental enamel malformation. Pathogenic variants in at least 33 genes cause syndromic or non-syndromic AI. Recently variants in RELT, encoding an orphan receptor in the tumour necrosis factor (TNF) superfamily, were found to cause recessive AI, as part of a syndrome encompassing small stature and severe childhood infections. Here we describe four additional families with autosomal recessive hypomineralised AI due to previously unreported homozygous mutations in RELT. Three families carried a homozygous missense variant in the fourth exon (c.164C>T, p.(T55I)) and a fourth family carried a homozygous missense variant in the 11th exon (c.1264C>T, p.(R422W)). We found no evidence of additional syndromic symptoms in affected individuals. Analyses of tooth microstructure with computerised tomography and scanning electron microscopy suggest a role for RELT in ameloblasts' coordination and interaction with the enamel matrix. Microsatellite genotyping in families segregating the T55I variant reveals a shared founder haplotype. These findings extend the RELT pathogenic variant spectrum, reveal a founder mutation in the UK Pakistani population and provide detailed analysis of human teeth affected by this hypomineralised phenotype, but do not support a possible syndromic presentation in all those with RELT-variant associated AI.     

FGFR2 mutation associated with clinical manifestations consistent with Antley-Bixler syndrome

The Antley-Bixler syndrome (ABS) is a rare syndrome with synostosis of cranial sutures and elbow joints as minimal diagnostic criteria. The inheritance has been suggested to be autosomal recessive based on two families with sib recurrence with both sexes being affected, and two cases born to consanguineous parents. We report the first case of ABS associated with an apparent dominant de novo mutation in the fibroblast growth factor receptor 2 (FGFR2) gene. The patient was found to be heterozygous for a C→G transversion at nucleotide 1064, which predicts a Ser351Cys amino acid substitution in the IgIII domain of FGFR2. Apart from the craniosynostosis and elbow ankylosis, our patient also presented with severe spinal dysraphism, the first report of such a finding in association with ABS. This suggests that FGFR2 is expressed as early as the fourth week of embryogenesis when somite formation occurs. We propose that the Antley-Bixler syndrome is an autosomal dominant condition with possible gonadal mosaicism. Alternatively, there may be two types of ABS: an autosomal dominant form and an autosomal recessive form. In light of our findings, FGFR mutations should be looked for in other craniosynostosis patients with elbow synostosis. Am. J. Med. Genet. 77:219–224, 1998. © 1998 Wiley-Liss, Inc.     

Somatic mutation of fibroblast growth factor receptor-3 (FGFR3) defines a distinct morphological subtype of high-grade urothelial carcinoma

FGFR3 mutations are common in low-grade urothelial carcinoma and represent a potential therapeutic target in this disease. Their incidence and functional role in high-grade urothelial carcinoma (HGUC), which displays an increased propensity for recurrence and muscularis propria invasion, is less well defined. We developed a mass spectrometry-based genotyping assay to define the incidence of FGFR3 mutations in a large clinically annotated set of urothelial carcinomas. FGFR3 mutations were found in 17% of HGUC versus 84% of low-grade lesions. Retrospective pathological review of the class of FGFR3 mutant HGUC revealed unique histological features, characterized by a bulky, exophytic component with branching papillary architecture as well as irregular nuclei with a koilocytoid appearance. The predictive value of this histological appearance was confirmed using a prospective set of 49 additional HGUCs. Prospective histological review was able to correctly predict for the presence of an FGFR3 mutation in 13/24 HGUC specimens that exhibited the distinct morphology (54%). All 25 specimens lacking the defined histological features were FGFR3 wild-type for a negative predictive value of 100%. Macrodissection of individual tumours confirmed the presence of the FGFR3 mutant allele in non-invasive and invasive, low and high-grade regions of individual tumours and in the lymph node metastases of patients whose tumours possessed the characteristic morphological signature, suggesting that FGFR3 mutations are not restricted to the more clinically indolent regions of HGUCs. These data suggest that histological screening of HGUCs followed by confirmatory genotyping can be used to enrich for the population of HGUCs most likely to harbour activating mutations in the FGFR-3 receptor tyrosine kinase. Histological review could thus aid in the development of targeted inhibitors of FGFR-3 by facilitating the identification of the subset of patients most likely to harbour activating mutations in the FGFR3 gene.     

Crouzon综合征基因突变检测

目的 研究1个Crouzon综合征家系及1例散发的Crouzon综合征患者的成纤维生长因子受体2(fibroblast growth factors receptor 2,FGFR2)基因突变情况.方法 在1个Crouzon综合征家系的10名成员,和另一例散发者的外周血提取基因组DNA,PCR扩增FGFR2基因的第8和10外显子(部分家族成员仅扩增第8外显子),产物纯化后直接进行DNA测序检测突变.结果 家系中3名成员及另1例散发者FGFR2基因第8外显子的833位核苷酸发生G→T的转换突变,该突变为错义突变,使该位点所编码的氨基酸由半胱氨酸变为苯丙氨酸(C278F).该突变为杂合子突变.结论 FGFR2基因突变是Crouzon综合征致病原因.     

Kallmann syndrome: 14 novel mutations in KAL1 and FGFR1 (KAL2)

Kallmann syndrome (KAL) combines hypogonadotropic hypogonadism and anosmia. Hypogonadism is due to Gonadotropin Releasing Hormone (GnRH) deficiency and anosmia is related to hypoplasia of the olfactory bulbs. Occasional symptoms include renal agenesis, bimanual synkinesia, cleft lip palate, dental agenesis. KAL is genetically heterogeneous and two genes have so far been identified, namely KAL1 (Xp22.3) and FGFR1/KAL2 (8p12), which underlie the X chromosome‐linked form and an autosomal dominant form of the disease, respectively. We studied a cohort of 98 unrelated Caucasian KAL patients. We identified KAL1 mutations in 14 patients, of which 7 (c.3G>A (p.M1?), g.IVS1+1G>T, c.570_571insA (p.R191fsX14), c.784G>C (p.R262P), c.958G>T (p.E320X), c.1651_1654delinsAGCT (p.P551_E552delinsSX), c.1711T>A (p.W571R)) have not been previously reported. In addition, we found FGFR1 mutations in 7 patients, namely c.303G>A (p.V102I), C.385A>C (p.D129A), c.810G>A (p.V273M), c.1093_1094delAG (p.R365fsX41), c.1561G>A (p.A520T), c.1836_1837insT (p.Y613fsX42), c.2190C>G (p.Y730X), all of which were novel mutations. In this study, unilateral renal agenesis and bimanual synkinesia were exclusively found associated with KAL1mutations, cleft palate and dental agenesia with FGFR1mutations. © 2004 Wiley‐Liss, Inc.     

Effect of FGF/FGFR pathway blocking on lung adenocarcinoma and its cancer-associated fibroblasts

Cancer-associated fibroblasts (CAFs) are known to promote tumourigenesis through various mechanisms. Fibroblast growth factor (FGF)/FGF receptor (FGFR)-dependent lung cancers have been described. We have developed a mouse model of lung adenocarcinoma that was constructed through the induction of Fgf9 overexpression in type 2 alveolar cells. The expression of Fgf9 in adult lungs resulted in the rapid development of multiple adenocarcinoma-like tumour nodules. Here, we have characterised the contribution of CAFs and the Fgf/Fgfr signalling pathway in maintaining the lung tumours initiated by Fgf9 overexpression. We found that CAF-secreted Fgf2 contributes to tumour cell growth. CAFs overexpressed Tgfb, Mmp7, Fgf9, and Fgf2; synthesised more collagen, and secreted inflammatory cell-recruiting cytokines. CAFs also enhanced the conversion of tumour-associated macrophages (TAMs) to the tumour-supportive M2 phenotype but did not influence angiogenesis. In vivo inhibition of Fgfrs during early lung tumour development resulted in significantly smaller and fewer tumour nodules, whereas inhibition in established lung tumours caused a significant reduction in tumour size and number. Fgfr inhibition also influenced tumour stromal cells, as it significantly abolished TAM recruitment and reduced tumour vascularity. However, the withdrawal of the inhibitor caused a significant recurrence/regrowth of Fgf/Fgfr-independent lung tumours. These recurrent tumours did not possess a higher proliferative or propagative potential. Our results provide evidence that fibroblasts associated with the Fgf9-induced lung adenocarcinoma provide multiple means of support to the tumour. Although the Fgfr blocker significantly suppressed the tumour and its stromal cells, it was not sufficient to completely eliminate the tumour, probably due to the emergence of alternative (resistance/maintenance) mechanism(s). This model represents an excellent tool to further study the complex interactions between CAFs, their related chemokines, and the progression of lung adenocarcinoma; it also provides further evidence to support the need for a combinatorial strategy to treat lung cancer. © 2019 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.     

Description of a new mutation and characterization of FGFR1, FGFR2, and FGFR3 mutations among Brazilian patients with syndromic craniosynostoses

Dominant mutations in three fibroblast growth factor receptor genes (FGFRs1-3) cause Crouzon, Jackson-Weiss, Pfeiffer, and Apert syndromes. In the present study, 50 Brazilian patients with these four syndromes (27 Apert, 17 Crouzon, 5 Pfeiffer, and 1 Jackson-Weiss patients) were screened for mutations in the FGFR1-3 genes. Except for one, all the Apert patients had either S252W (n = 16) or P253R (n = 10) mutations. The remaining Apert case is atypical with a mutation altering the splice site of FGFR2 exon IIIc. The Pfeiffer patients had mutations in one of the FGFR genes: three in FGFR2, one in FGFR1, and one in FGFR3. In contrast, only 8 of the 17 Crouzon patients studied had a mutation in either FGFR2 (n = 7) or FGFR3 locus (n = 1). Mutations in the FGFR2 locus account for most (93%) of our syndromic craniosynostotic cases, whereas 5% had mutations in the FGFR3 locus and only 2% had mutations in the FGFR1 gene. Except for one, all the other mutations were reported previously in craniosynostotic patients from other populations. Interestingly, the mutation C278F, previously described in Crouzon and Pfeiffer cases, was here identified in a familial case with Jackson-Weiss. Also, unexpectedly, a common mutation altering the splice site of the FGFR2 exon IIIc was found in one Apert and two Pfeiffer patients. In addition, we identified a new mutation (A337P) in the FGFR2 exon IIIc associated with Crouzon phenotype. Am. J. Med. Genet. 78:237–241, 1998. © 1998 Wiley-Liss, Inc.     

Functional characterization of MLH1 missense variants identified in lynch syndrome patients

Germline mutations in the human DNA mismatch repair (MMR) genes MSH2 and MLH1 are associated with the inherited cancer disorder Lynch syndrome (LS), also known as hereditary nonpolyposis colorectal cancer or HNPCC. A proportion of MSH2 and MLH1 mutations found in suspected LS patients give rise to single amino acid substitutions. The functional consequences in regard to pathogenicity of many of these variants are unclear. We have examined the functionality of a panel of MLH1 missense mutations found in LS families, by testing the variant proteins in functional assays, addressing subcellular localization, and protein–protein interaction with the dimer partner PMS2 and the MMR‐associated exonuclease 1. We show that a significant proportion of examined variant proteins have functional defects in either subcellular localization or protein–protein interactions, which is suspected to lead to the cancer phenotype observed in patients. Moreover, the obtained results correlate well with reported MMR activity and with in silico analysis for a majority of the variants. Hum Mutat 33:1647–1655, 2012. © 2012 Wiley Periodicals, Inc.