MAP2K1-Mutated Melanocytic Neoplasms With a SPARK-Like Morphology.

ABSTRACT: Specific alterations involving MAPK genes (MAP3K8 fusions, MAP3K3 fusions) have been recently detected in a subgroup of spitzoid neoplasms that seem to constitute a distinctive clinicopathologic group, occur mostly in younger patients (median age 18 years) and present with atypical histologic features associated with frequent homozygous deletion of CDKN2A, qualifying a high proportion of them as Spitz melanoma (malignant Spitz tumor). Apart from lesions with spitzoid morphology harboring MAP3K8 or MAP3K3 fusion, a single case with MAP2K1 deletion has been identified. The authors report herein 4 melanocytic lesions with a MAP2K1 mutation, all showing similar microscopic appearances, including spitzoid cytology and dysplastic architectural features, resembling so-called SPARK nevus, suggesting that these lesions may represent another distinctive group.

Pre- and postnatal growth failure with microcephaly due to two novel heterozygous IGF1R mutations and response to growth hormone treatment.

AIM: To explore the phenotype and response to growth hormone in patients with heterozygous mutations in the insulin-like growth factor I receptor gene (IGF1R). METHODS: Children with short stature, microcephaly, born SGA combined with biochemical sign of IGF-I insensitivity were analysed for IGF1R mutations or deletions using Sanger sequencing and Multiple ligation-dependent probe amplification analysis. RESULTS: In two families, a novel heterozygous non-synonymous missense IGF1R variant was identified. In family 1, c.3364G > T, p.(Gly1122Cys) was found in the proband and co-segregated perfectly with the phenotype in three generations. In family 2, a de novo variant c.3530G > A, p.(Arg1177His) was detected. Both variants were rare, not present in the GnomAD database. Three individuals carrying IGF1R mutations have received rhGH treatment. The average gain in height SDS during treatment was 0.42 (range: 0.26-0.60) and 0.64 (range: 0.32-0.86) after 1 and 2 years of treatment, respectively. CONCLUSION: Our study presents two heterozygous IGF1R mutations causing pre- and postnatal growth failure and microcephaly and also indicates that individuals with heterozygous IGF1R mutations can respond to rhGH treatment. The findings highlight that sequencing of the IGF1R should be considered in children with microcephaly and short stature due to pre- and postnatal growth failure.

Genetic screening in sudden cardiac death in the young can save future lives.

BACKGROUND: Autopsy of sudden cardiac death (SCD) in the young shows a structurally and histologically normal heart in about one third of cases. Sudden death in these cases is believed to be attributed in a high percentage to inherited arrhythmogenic diseases. The purpose of this study was to investigate the value of performing post-mortem genetic analysis for autopsy-negative sudden unexplained death (SUD) in 1 to 35 year olds. METHODS AND RESULTS: From January 2009 to December 2011, samples from 15 cases suffering SUD were referred to the Department of Clinical Genetics, Umeå University Hospital, Sweden, for molecular genetic evaluation. PCR and bidirectional Sanger sequencing of genes important for long QT syndrome (LQTS), short QT syndrome (SQTS), Brugada syndrome type 1 (BrS1), and catecholaminergic polymorphic ventricular tachycardia (CPVT) (KCNQ1, KCNH2, SCN5A, KCNE1, KCNE2, and RYR2) was performed. Multiplex ligation-dependent probe amplification (MLPA) was used to detect large deletions or duplications in the LQTS genes. Six pathogenic sequence variants (four LQTS and two CPVT) were discovered in 15 SUD cases (40%). Ten first-degree family members were found to be mutation carriers (seven LQTS and three CPVT). CONCLUSION: Cardiac ion channel genetic testing in autopsy-negative sudden death victims has a high diagnostic yield, with identification of the disease in 40 of families. First-degree family members should be offered predictive testing, clinical evaluation, and treatment with the ultimate goal to prevent sudden death.

A missense mutation in the aggrecan C-type lectin domain disrupts extracellular matrix interactions and causes dominant familial osteochondritis dissecans.

Osteochondritis dissecans is a disorder in which fragments of articular cartilage and subchondral bone dislodge from the joint surface. We analyzed a five-generation family in which affected members had autosomal-dominant familial osteochondritis dissecans. A genome-wide linkage analysis identified aggrecan (ACAN) as a prime candidate gene for the disorder. Sequence analysis of ACAN revealed heterozygosity for a missense mutation (c.6907G > A) in affected individuals, resulting in a p.V2303M amino acid substitution in the aggrecan G3 domain C-type lectin, which mediates interactions with other proteins in the cartilage extracellular matrix. Binding studies with recombinant mutated and wild-type G3 proteins showed loss of fibulin-1, fibulin-2, and tenascin-R interactions for the V2303M protein. Mass spectrometric analyses of aggrecan purified from patient cartilage verified that V2303M aggrecan is produced and present in the tissue. Our results provide a molecular mechanism for the etiology of familial osteochondritis dissecans and show the importance of the aggrecan C-type lectin interactions for cartilage function in vivo.

Founder mutations characterise the mutation panorama in 200 Swedish index cases referred for Long QT syndrome genetic testing.

BACKGROUND: Long QT syndrome (LQTS) is an inherited arrhythmic disorder characterised by prolongation of the QT interval on ECG, presence of syncope and sudden death. The symptoms in LQTS patients are highly variable, and genotype influences the clinical course. This study aims to report the spectrum of LQTS mutations in a Swedish cohort. METHODS: Between March 2006 and October 2009, two hundred, unrelated index cases were referred to the Department of Clinical Genetics, Umeå University Hospital, Sweden, for LQTS genetic testing. We scanned five of the LQTS-susceptibility genes (KCNQ1, KCNH2, SCN5A, KCNE1, and KCNE2) for mutations by DHPLC and/or sequencing. We applied MLPA to detect large deletions or duplications in the KCNQ1, KCNH2, SCN5A, KCNE1, and KCNE2 genes. Furthermore, the gene RYR2 was screened in 36 selected LQTS genotype-negative patients to detect cases with the clinically overlapping disease catecholaminergic polymorphic ventricular tachycardia (CPVT). RESULTS: In total, a disease-causing mutation was identified in 103 of the 200 (52%) index cases. Of these, altered exon copy numbers in the KCNH2 gene accounted for 2% of the mutations, whereas a RYR2 mutation accounted for 3% of the mutations. The genotype-positive cases stemmed from 64 distinct mutations, of which 28% were novel to this cohort. The majority of the distinct mutations were found in a single case (80%), whereas 20% of the mutations were observed more than once. Two founder mutations, KCNQ1 p.Y111C and KCNQ1 p.R518*, accounted for 25% of the genotype-positive index cases. Genetic cascade screening of 481 relatives to the 103 index cases with an identified mutation revealed 41% mutation carriers who were at risk of cardiac events such as syncope or sudden unexpected death. CONCLUSION: In this cohort of Swedish index cases with suspected LQTS, a disease-causing mutation was identified in 52% of the referred patients. Copy number variations explained 2% of the mutations and 3 of 36 selected cases (8%) harboured a mutation in the RYR2 gene. The mutation panorama is characterised by founder mutations (25%), even so, this cohort increases the amount of known LQTS-associated mutations, as approximately one-third (28%) of the detected mutations were unique.

Characterization of a recurrent germ line mutation of the E-cadherin gene: implications for genetic testing and clinical management.

PURPOSE: To identify germ line CDH1 mutations in hereditary diffuse gastric cancer (HDGC) families and develop guidelines for management of at risk individuals. EXPERIMENTAL DESIGN: We ascertained 31 HDGC previously unreported families, including 10 isolated early-onset diffuse gastric cancer (DGC) cases. Screening for CDH1 germ line mutations was done by denaturing high-performance liquid chromatography and automated DNA sequencing. RESULTS: We identified eight inactivating and one missense CDH1 germ line mutation. The missense mutation conferred in vitro loss of protein function. Two families had the previously described 1003C>T nonsense mutation. Haplotype analysis revealed this to be a recurrent and not a founder mutation. Thirty-six percent (5 of 14) of the families with a documented DGC diagnosed before the age of 50 and other cases of gastric cancer carried CDH1 germ line mutations. Two of 10 isolated cases of DGC in individuals ages <35 years harbored CDH1 germ line mutations. One mutation positive family was ascertained through a family history of lobular breast cancer (LBC) and another through an individual with both DGC and LBC. Occult DGC was identified in five of six prophylactic gastrectomies done on asymptomatic, endoscopically negative 1003C>T mutation carriers. CONCLUSIONS: In addition to families with a strong history of early-onset DGC, CDH1 mutation screening should be offered to isolated cases of DGC in individuals ages <35 years and for families with multiple cases of LBC, with any history of DGC or unspecified GI malignancies. Prophylactic gastrectomy is potentially a lifesaving procedure and clinical breast screening is recommended for asymptomatic mutation carriers.

Genetic analysis of the RNASEL gene in hereditary, familial, and sporadic prostate cancer.

PURPOSE: The RNASEL gene has been proposed as a candidate gene for the HPC1 locus through a positional cloning and candidate gene approach. Cosegregation between the truncating mutation E265X and disease in a hereditary prostate cancer (HPC) family and association between prostate cancer risk and the common missense variant R462Q has been reported. To additionally evaluate the possible role of RNASEL in susceptibility to prostate cancer risk, we performed a comprehensive genetic analysis of sequence variants in RNASEL in the Swedish population. EXPERIMENTAL DESIGN: Using 1624 prostate cancer cases and 801 unaffected controls, the truncating mutation E265X and five common sequence variants, including the two missense mutations R462Q and D541E, were evaluated for association between genotypes/haplotypes and prostate cancer risk. RESULTS: The prevalence of E265X carriers among unaffected controls and prostate cancer patients was almost identical (1.9 and 1.8% in controls and cases, respectively), and evidence for segregation of E265X with disease was not observed within any HPC family. Overall, the analyses of common sequence variants provided limited evidence for association with prostate cancer risk. We found a marginally significant inverse association between the missense mutation D541E and sporadic prostate cancer risk (odds ratio, 0.77; 95% confidence interval, 0.59-1.00) and reduced risk of prostate cancer in carriers of two different haplotypes being completely discordant. CONCLUSIONS: Considering the high quality in genotyping and the size of this study, these results provide solid evidence against a major role of RNASEL in prostate cancer etiology in Sweden.

Systematic replication study of reported genetic associations in prostate cancer: Strong support for genetic variation in the androgen pathway.

BACKGROUND: Association studies have become a common and popular method to identify genetic variants predisposing to complex diseases. Despite considerable efforts and initial promising findings, the field of prostate cancer genetics is characterized by inconclusive reports and no prostate cancer gene has yet been established. METHODS: We performed a literature review and identified 79 different polymorphisms reported to influence prostate cancer risk. Of these, 46 were selected and tested for association in a large Swedish population-based case-control prostate cancer population. RESULTS: We observed significant (P < 0.05) confirmation for six polymorphisms located in five different genes. Three of them coded for key enzymes in the androgen biosynthesis and response pathway; the CAG repeat in the androgen receptor (AR) gene (P = 0.03), one SNP in the CYP17 gene (P = 0.04), two SNPs in the SRD5A2 gene (P = 0.02 and 0.02, respectively), a deletion of the GSTT1 gene (P = 0.006), and one SNP in the MSR1 gene, IVS5-59C > A, (P = 0.009). CONCLUSIONS: Notwithstanding the difficulties to replicate findings in genetic association studies, our results strongly support the importance of androgen pathway genes in prostate cancer etiology.

Comprehensive genetic evaluation of common E-cadherin sequence variants and prostate cancer risk: strong confirmation of functional promoter SNP.

The E-cadherin gene (CDH1) has been proposed as a prostate cancer (PC) susceptibility gene in several studies. Aberrant protein expression has been related to prognosis and progression in PC. In addition, a functional promoter SNP (rs16260) has been found to associate with PC risk. We performed a comprehensive genetic analysis of CDH1 by using the method of haplotype tagged SNPs in a large Swedish population-based case-control study consisting of 801 controls and 1,636 cases. In addition, Swedish PC families comprising a total of 157 cases sampled for DNA were analyzed for selected SNPs. Seven SNPs, including the promoter SNP rs16260, that captured over 96% of CDH1 haplotype variation were selected as haplotype tagging SNPs and analyzed for associated PC risk. We observed significant confirmation of rs16260 (P=0.003) for cases with a positive family history of PC (FH+) both in an independent case-control population and in PC families. In addition, a common haplotype (HapB, 25%) including the variant allele of rs16260 was associated (P=0.004) with PC risk among FH+ cases. The promoter SNP rs16260 as well as HapB were significantly transmitted to affected offspring in PC families. We report strong confirmation of the association between PC risk in FH+ cases and a functional CDH1 promoter SNP in an independent population. In conjunction with the biological importance of CDH1 our findings encourage further evaluation of genetic variation in CDH1 in relation to PC etiology. Due to the difficulties in replication of genetic association studies, this finding is unusual and novel.

Linkage analysis of prostate cancer susceptibility: confirmation of linkage at 8p22-23.

Frequent loss of heterogeneity in prostate cancer cells and linkage studies of families affected by hereditary prostate cancer (HPC) have implied that the short arm of chromosome 8, specifically 8p22-23, may harbor a prostate-cancer-susceptibility gene. In a recent study, seven potentially important mutations in the macrophage scavenger receptor 1 gene (MSR1), located at 8p22, were observed in families affected with HPC, and an indication of co-segregation between these mutations and prostate cancer was reported. In an attempt to confirm linkage at 8p22-23, we performed linkage analyses in 57 families affected with HPC (ascertained throughout Sweden) by using 13 markers on the short arm of chromosome 8. In the complete set of families, evidence for prostate cancer linkage was observed at 8p22-23, with a peak hold of 1.08 (P=0.03), observed at D8S1731, approximately 1 cM centromeric to the MSR1 gene. At marker D8S1135, the closest marker to MSR1, a hlod of 1.07 (P=0.03) was observed. Evidence of linkage was seen in families with early-onset HPC and in families with a small number of affected individuals. The peak multipoint non-parametric linkage score was 2.01 (P=0.03) at D8S552 in the 14 pedigrees with mean age at onset <65 years, and 2.25 (P=0.01) at D8S1731 in the 36 pedigrees with fewer than five affected family members. Thus, we have confirmed evidence for prostate cancer linkage at 8p22-23. Follow-up studies to evaluate the possible association between prostate cancer and genes in this region, especially the MSR1 gene, are warranted.

Germline mutations in E-cadherin do not explain association of hereditary prostate cancer, gastric cancer and breast cancer.

Somatic mutations in the E-cadherin (CDH1) gene have frequently been reported in cases with diffuse gastric and lobular breast cancers. Recently, germline mutations have been identified in families with diffuse gastric cancers. In families with hereditary prostate cancer (HPC), a significant association of prostate cancer, gastric and/or breast cancer has been observed in epidemiological studies. The aim of this study was to investigate if germline mutations in CDH1 could explain the risk for cancer in HPC families with an excess of gastric and breast cancer. In total, 17 members from 13 HPC families and 3 members from 3 families with hereditary gastric cancer (HGC) were screened for germline CDH1 sequence alterations using PCR/Denaturing HPLC for initial screening of nucleotide variants followed by confirmatory direct sequencing analysis. The frequency of identified novel germline mutations were tested for in 136 cases with hereditary prostate cancer and 215 cases of sporadic prostate cancer with 422 age matched controls in an allelic discrimination assay. In total, 8 sequence variants were detected in 20 samples tested. In the HPC families, we found 2 missense mutations, A592T in exon 12 and a novel D777N in exon 15 and a mutation in intron 5, 687+92T>A. A previously known polymorphism in exon 13 and 3 sequence variations in introns and untranslated regions were also found, of which the significance is unknown. In HGC-023 with early onset diffuse gastric cancer a truncating mutation, R335X, was identified in exon 7. None of the missense mutations or 687+92T>A were found in the extended HPC material or in the sporadic prostate cancer cases with age-matched controls in the allelic discrimination assay. We found several germline mutations of unknown clinical significance in the CDH1 gene that probably do not explain the association of prostate, gastric and/or breast cancers in the HPC-families. Two missense mutations and a mutation in intron 5 were identified that do not influence the risk of hereditary or sporadic prostate cancer in general and are considered to be pedigree specific. In a family with hereditary gastric cancer of the diffuse type, we identified the first truncating germline mutation in a Scandinavian family.

-160C/A polymorphism in the E-cadherin gene promoter and risk of hereditary, familial and sporadic prostate cancer.

The E-cadherin (CDH1) gene has been associated with prostate carcinogenesis. The C/A polymorphism--160 base pairs relative to the transcription start site has been shown to decrease gene transcription. We analyzed the association between this polymorphism and the risk of sporadic, familial (2 close relatives) and hereditary (3 or more close relatives) prostate cancer. We combined data from 3 population-based epidemiologic studies in Sweden encompassing altogether 1,036 prostate cancer cases and 669 controls that were genotyped for the short nucleotide polymorphism. Odds ratios with 95% confidence intervals were estimated through unconditional logistic regression. We found no significant association between the A-allele and sporadic (OR = 1.0; 95% CI = 0.8-1.2) or familial (OR = 1.4; 95% CI = 0.9-2.2) prostate cancer. In contrast, risk of hereditary cancer was increased among heterozygote CA carriers (OR = 1.7; 95% CI = 1.0-2.7) and particularly among homozygote AA carriers (OR = 2.6; 95% CI = 1.4-4.9). Our data indicate that the -160 single nucleotide polymorphism in CDH1 is a low-penetrant prostate cancer susceptibility gene that might explain a proportion of familial and notably hereditary prostate cancer.

Analysis of the macrophage scavenger receptor 1 gene in Swedish hereditary and sporadic prostate cancer.

BACKGROUND: The macrophage scavenger receptor 1 (MSR1) gene on chromosome 8p22 was recently reported as a candidate gene for hereditary prostate cancer (HPC). Here, we further elucidate the role of MSR1 in both Swedish families with HPC and in a cohort of unselected prostate cancer. METHODS: DNA samples from 83 Swedish HPC families and 215 unselected population based cases of prostate cancer as well as 425 age-matched controls were genotyped. RESULTS: A total of 18 variants were identified, including 2 exonic, 7 intronic changes, and 9 changes in the 5'- or 3'-uncoding region. Of the two exonic changes, one previously reported truncation mutation was identified, a R293X nonsense mutation. This mutation was found in 2 of the 83 (2.4%) HPC families. The R293X mutation was found more frequently in men with PC (4.9%) than in unaffected men (2.7%), consistent with previous published results, however our results were not significant (P = 0.16). To additionally test for potential association of common sequence variants and increased risk for the disease, five common polymorphisms (PRO3, INDEL1, IVS5-57, P275A, INDEL7) were genotyped in the group of 215 prostate cancer cases and 425 age-matched controls. No association between any of the five common sequence variants and prostate cancer were found. CONCLUSION: Our results suggest that mutations in MSR1 gene might play a role in prostate cancer susceptibility, particularly the R293X mutation. This study warrants further investigations of the role of MSR1 in prostate cancer etiology.

Genome-wide scan of Swedish families with hereditary prostate cancer: suggestive evidence of linkage at 5q11.2 and 19p13.3.

BACKGROUND: Prostate cancer (CaP) is a common disorder with multiple genetic and environmental factors contributing to the disease. CaP susceptibility loci can be identified through genome-wide scans of high-risk families. METHODS: Allele sharing at 405 markers, distributed across the genome, among 50 families with hereditary prostate cancer, ascertained throughout Sweden, was evaluated through linkage analyses. Genotype data were analyzed utilizing multipoint parametric and non-parametric methods. RESULTS: Two regions provided suggestive evidence for linkage: 19p13.3 (marker D19S209, LOD = 2.91, P = 0.0001) and 5q11.2 (marker D5S407, LOD = 2.24, P = 0.0007). Additional regions with moderate evidence for linkage in the complete set of families, or stratified subsets, were observed on chromosome 1, 4, 6, 7, 8, and X. CONCLUSIONS: Our results provide strong confirmatory evidence of linkage at 19q13.3 and 5q11.2. The lack of confirmation of linkage at several loci identified in other genome-wide scans emphasizes the need to combine linkage data between research groups.