Kristina Lagerstedt

The Clinical Phenotype of Lynch Syndrome Due to Germ-Line PMS2 Mutations

BACKGROUND & AIMSnAlthough the clinical phenotype of Lynch syndrome (also known as hereditary nonpolyposis colorectal cancer) has been well described, little is known about disease in PMS2 mutation carriers. Now that mutation detection methods can discern mutations in PMS2 from mutations in its pseudogenes, more mutation carriers have been identified. Information about the clinical significance of PMS2 mutations is crucial for appropriate counseling. Here, we report the clinical characteristics of a large series of PMS2 mutation carriers.nnnMETHODSnWe performed PMS2 mutation analysis using long-range polymerase chain reaction and multiplex ligation-dependent probe amplification for 99 probands diagnosed with Lynch syndrome-associated tumors showing isolated loss of PMS2 by immunohistochemistry. Penetrance was calculated using a modified segregation analysis adjusting for ascertainment.nnnRESULTSnGerm-line PMS2 mutations were detected in 62% of probands (n = 55 monoallelic; 6 biallelic). Among families with monoallelic PMS2 mutations, 65.5% met revised Bethesda guidelines. Compared with the general population, in mutation carriers, the incidence of colorectal cancer was 5.2-fold higher, and the incidence of endometrial cancer was 7.5-fold higher. In North America, this translates to a cumulative cancer risk to age 70 years of 15%-20% for colorectal cancer, 15% for endometrial cancer, and 25%-32% for any Lynch syndrome-associated cancer. No elevated risk for non-Lynch syndrome-associated cancers was observed.nnnCONCLUSIONSnPMS2 mutations contribute significantly to Lynch syndrome, but the penetrance for monoallelic mutation carriers appears to be lower than that for the other mismatch repair genes. Modified counseling and cancer surveillance guidelines for PMS2 mutation carriers are proposed.

Stickler syndrome caused by COL2A1 mutations: Genotype-phenotype correlation in a series of 100 patients

Stickler syndrome is an autosomal dominant connective tissue disorder caused by mutations in different collagen genes. The aim of our study was to define more precisely the phenotype and genotype of Stickler syndrome type 1 by investigating a large series of patients with a heterozygous mutation in COL2A1. In 188 probands with the clinical diagnosis of Stickler syndrome, the COL2A1 gene was analyzed by either a mutation scanning technique or bidirectional fluorescent DNA sequencing. The effect of splice site alterations was investigated by analyzing mRNA. Multiplex ligation-dependent amplification analysis was used for the detection of intragenic deletions. We identified 77 different COL2A1 mutations in 100 affected individuals. Analysis of the splice site mutations showed unusual RNA isoforms, most of which contained a premature stop codon. Vitreous anomalies and retinal detachments were found more frequently in patients with a COL2A1 mutation compared with the mutation-negative group (P<0.01). Overall, 20 of 23 sporadic patients with a COL2A1 mutation had either a cleft palate or retinal detachment with vitreous anomalies. The presence of vitreous anomalies, retinal tears or detachments, cleft palate and a positive family history were shown to be good indicators for a COL2A1 defect. In conclusion, we confirm that Stickler syndrome type 1 is predominantly caused by loss-of-function mutations in the COL2A1 gene as >90% of the mutations were predicted to result in nonsense-mediated decay. On the basis of binary regression analysis, we developed a scoring system that may be useful when evaluating patients with Stickler syndrome.

DNA repair genes are selectively mutated in diffuse large B cell lymphomas.

Mutations in DNA damage response and repair genes correlate with genomic instability in diffuse large B cell lymphomas.

Polymorphisms of estrogen receptor β gene are associated with hypospadias

Introduction: Hypospadias is a common male congenital urethral malformation, defined as the displacement of the urethral meatus ventrally from the tip of the glans penis. The importance of androgen receptor in male external genitalia development has been well recognized. Recently, the presence of active estrogen receptors (ER) in the developing male external genitalia has also been demonstrated. There are two isoforms of the human estrogen receptor, ESR1 and ESR2, which occur, with distinct tissue and cell patterns of expression. We hypothesized that modifications in these nuclear receptors’ genes could lead to hypospadias. Materials and methods: We screened 60 boys with hypospadias for mutations in the coding regions of ESR1 and ESR2 genes, by denaturing high-performance liquid chromatography and automated sequence analysis. We also genotyped the CA repeat polymorphism in ESR2 and the TA repeat polymorphism in ESR1. Results: The CA repeat polymorphism in ESR2 is prolonged in hypospadias patients compared to controls (p<0.05). Prolongation of this CA repeat polymorphism has previously been associated with lower levels of testosterone. Six patients presented the genetic variant 2681-4AĞ (rs944050) in the heterozygous form in ESR2, which was a significantly higher frequency than in the control population (p<0.05). One of these patients also presented a 266_267insC in exon 1 of ESR2, which is also a known single nucleotide polymorphism (SNP; rs3832949). In ESR1, no significant gene alteration was found to be associated with hypospadias. Conclusions: Our results suggest that variations in the ESR2 might influence susceptibility to hypospadias.

Loss of mismatch repair protein immunostaining in colorectal adenomas from patients with hereditary nonpolyposis colorectal cancer.

Colorectal adenomas occur at younger age, at increased frequency and have a greater tendency for malignant transformation in patients with hereditary nonpolyposis colorectal cancer (HNPCC). We performed immunostaining for the mismatch repair proteins MLH1, PMS2, MSH2 and MSH6 in 35 colorectal adenomas from 26 patients with HNPCC and identified loss of immunostaining in 23/35 (0.66) adenomas. Loss of mismatch repair protein immunostaining was particularly frequent in large (>5u2009mm) (14/16) and proximally located (13/15) adenomas, whereas the gene mutated—MLH1 or MSH2—and the type of mutation did not seem to affect the results. We conclude that loss of mismatch repair protein immunostaining is detected at a lower rate in adenomas than in carcinomas associated with HNPCC. Adenomatous tissue can thus be used for immunostaining of mismatch repair proteins in clinical investigations of HNPCC, but whereas loss of immunostaining may pinpoint the gene affected and thereby guide mutation analysis, retained staining cannot exclude that the adenoma developed as part of the syndrome due to reduced sensitivity. However, the analysis has a greater chance of being informative if large and proximally located adenomas are selected.

New ZMPSTE24 (FACE1) mutations in patients affected with restrictive dermopathy or related progeroid syndromes and mutation update

Restrictive dermopathy (RD) is a rare and extremely severe congenital genodermatosis, characterized by a tight rigid skin with erosions at flexure sites, multiple joint contractures, low bone density and pulmonary insufficiency generally leading to death in the perinatal period. RD is caused in most patients by compound heterozygous or homozygous ZMPSTE24 null mutations. This gene encodes a metalloprotease specifically involved in lamin A post-translational processing. Here, we report a total of 16 families for whom diagnosis and molecular defects were clearly established. Among them, we report seven new ZMPSTE24 mutations, identified in classical RD or Mandibulo-acral dysplasia (MAD) affected patients. We also report nine families with one or two affected children carrying the common, homozygous thymine insertion in exon 9 and demonstrate the lack of a founder effect. In addition, we describe several new ZMPSTE24 variants identified in unaffected controls or in patients affected with non-classical progeroid syndromes. In addition, this mutation update includes a comprehensive search of the literature on previously described ZMPSTE24 mutations and associated phenotypes. Our comprehensive analysis of the molecular pathology supported the general rule: complete loss-of-function of ZMPSTE24 leads to RD, whereas other less severe phenotypes are associated with at least one haploinsufficient allele.

Dystrophia Helsinglandica: a new type of hereditary corneal recurrent erosions with late subepithelial fibrosis

Purpose:u2002 To describe the phenotype of an autosomal‐dominant corneal dystrophy with an early onset of recurrent corneal erosions and development of subepithelial fibrosis in the cornea, and also to exclude genetic linkage to known corneal dystrophies with autosomal‐dominant inheritance and clinical resemblance.

A new corneal disease with recurrent erosive episodes and autosomal-dominant inheritance

Purpose:u2002 The aim of this study was to characterize the phenotype in a large family with autosomal‐dominant recurrent corneal erosions, and also to exclude genetic linkage to known autosomal‐dominant inherited corneal dystrophies with clinical resemblance.

Absence of motilin gene mutations in infantile hypertrophic pyloric stenosis

BACKGROUNDnErythromycin treatment before 2 weeks of age has been shown to increase the risk of infantile hypertrophic pyloric stenosis (IHPS) up to 10 times. Erythromycin is a motilin agonist, a hormone that induces gastrointestinal contractions. The purpose of this study was to investigate if mutations in the motilin gene (MLN) cause IHPS or if the V15A polymorphism in MLN is associated with the disease.nnnMETHODSnThe MLN was screened for mutations, and the V15A polymorphism was determined in a total of 57 patients with IHPS using polymerase chain reaction and DNA sequencing. The polymorphism genotype and allele frequencies among the patients were compared with 184 controls.nnnRESULTSnWe detected 3 different, not previously reported, MLN sequence variants in 4 patients. One of these variants results in an amino acid exchange in the motilin signal peptide (A25G). All 3 detected sequence variants were also found in controls or were not inherited with the disease. We found no significant association between the V15A polymorphism and the disease.nnnCONCLUSIONSnWe have excluded the MLN coding region as a major cause of IHPS. Future studies will evaluate the importance of this metabolic pathway in the pathogenesis of IHPS.

The BRCA1 exon 13 duplication in the Swedish population

Barbara Kremeyer, Maria Soller, Kristina Lagerstedt, Paula Maguire, Sylvie Mazoyer, Margareta Nordling, Jan Wahlström and Annika Lindblom Department of Molecular Medicine, Karolinska Institutet, Stockholm, Sweden; Laboratoire de Génétique FRE2692, Faculté de Médecine Rockefeller, Université Claude Bernard Lyon I, Lyon, France; Department of Clinical Genetics, Sahlgrenska University Hospital, Gothenburg University, Gothenburg, Sweden