Every year more than 800 patients in Denmark are diagnosed with renal cell carcinoma (RCC) of which 3-5% are expected to be part of a hereditary renal cancer syndrome. We performed genetic screening ...of causative and putative RCC-genes (VHL, FH, FLCN, MET, SDHB, BAP1, MITF, CDKN2B) in RCC-patients suspected of a genetic predisposition.
The cohort consisted of forty-eight Danish families or individuals with early onset RCC, a family history of RCC, a family history of RCC and melanoma or both RCC- and melanoma diagnosis in the same individual. DNA was extracted from peripheral blood samples or cancer-free formalin-fixed paraffin-embedded tissue.
One start codon variant of unknown clinical significance (VUS) (c.3G>A, p.Met1Ile) and one missense VUS (c.631A>C, p.Met211Leu) was found in VHL in a patient with RCC-onset at twenty-eight years of age but without other manifestations or family history of von Hippel-Lindau (VHL). Furthermore, in three families we found three different variants in BAP1, one of which was a novel non-segregating missense variant (c.1502G>A, p.Ser501Asn) in a family with two brothers affected with RCC. Finally, we found the known E318K-substitution in MITF in a RCC-affected member of a family with multiple melanomas. No variants were detected in CDKN2B.
Although we did find three VUS's in BAP1 in three families and a pathogenic variant in MITF in one family, pathogenic germline variants in BAP1, MITF or CDKN2B are not frequent causes of hereditary renal cancer in Denmark. It is possible that the high prevalence of risk factors such as male gender, smoking and obesity has influenced the development of cancer in the patients of the current study. Further investigations into putative predisposing genes and risk factors of RCC are necessary to enable better prediction of renal cancer risk or presymptomatic testing of relatives in hereditary renal cancer families.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The 6%–9% risk of an untoward outcome previously established by Warburton for prenatally detected de novo balanced chromosomal rearrangements (BCRs) does not account for long-term morbidity. We ...performed long-term follow-up (mean 17 years) of a registry-based nationwide cohort of 41 individuals carrying a prenatally detected de novo BCR with normal first trimester screening/ultrasound scan. We observed a significantly higher frequency of neurodevelopmental and/or neuropsychiatric disorders than in a matched control group (19.5% versus 8.3%, p = 0.04), which was increased to 26.8% upon clinical follow-up. Chromosomal microarray of 32 carriers revealed no pathogenic imbalances, illustrating a low prognostic value when fetal ultrasound scan is normal. In contrast, mate-pair sequencing revealed disrupted genes (ARID1B, NPAS3, CELF4), regulatory domains of known developmental genes (ZEB2, HOXC), and complex BCRs associated with adverse outcomes. Seven unmappable autosomal-autosomal BCRs with breakpoints involving pericentromeric/heterochromatic regions may represent a low-risk group. We performed independent phenotype-aware and blinded interpretation, which accurately predicted benign outcomes (specificity = 100%) but demonstrated relatively low sensitivity for prediction of the clinical outcome in affected carriers (sensitivity = 45%–55%). This sensitivity emphasizes the challenges associated with prenatal risk prediction for long-term morbidity in the absence of phenotypic data given the still immature annotation of the morbidity genome and poorly understood long-range regulatory mechanisms. In conclusion, we upwardly revise the previous estimates of Warburton to a morbidity risk of 27% and recommend sequencing of the chromosomal breakpoints as the first-tier diagnostic test in pregnancies with a de novo BCR.
Background: Evaluation of the pathogenicity of a gene variant of unknown significance
(VUS) is crucial for molecular diagnosis and genetic counseling, but can be challenging. This is especially
so in ...phenotypically variable diseases, such as von Hippel-Lindau disease (vHL). vHL is caused
by germline mutations in the VHL gene, which predispose to the development of multiple tumors such
as central nervous system hemangioblastomas and renal cell carcinoma (RCC).
Objective: We propose a method for the evaluation of VUS pathogenicity through our experience with
the VHL missense mutation c.241C>T (p.P81S).
Method: 1) Clinical evaluation of known variant carriers: We evaluated a family of five VHL p.P81S
carriers, as well as the clinical characteristics of all the p.P81S carriers reported in the literature; 2)
Evaluation of tumor tissue via genetic analysis, histology, and immunohistochemistry (IHC); 3) Assessment
of the variant's impact on protein structure and function, using multiple databases, in silico algorithms,
and reports of functional studies.
Results: Only one family member had clinical signs of vHL with early-onset RCC. IHC analysis
showed no VHL protein expressed in the tumor, consistent with biallelic VHL inactivation. The majority
of in silico algorithms reported p.P81S as possibly pathogenic in relation to vHL or RCC, but there were
discrepancies. Functional studies suggest that p.P81S impairs the VHL protein's function.
Conclusion: The VHL p.P81S mutation is most likely a low-penetrant pathogenic variant predisposing
to RCC development. We suggest the above-mentioned method for VUS evaluation with use of different
methods, especially a variety of in silico methods and tumor tissue analysis.
Both environmental and host factors influence risk of cutaneous melanoma (CM), and worldwide, the incidence varies depending on constitutional determinants of skin type and pigmentation, latitude, ...and patterns of sun exposure. We performed genetic analysis of CDKN2A, CDK4, BAP1, MC1R, and MITFp.E318K in Danish high-risk melanoma cases and found CDKN2A germline mutations in 11.3% of CM families with three or more affected individuals, including four previously undescribed mutations. Rare mutations were also seen in CDK4 and BAP1, while MC1R variants were common, occurring at more than twice the frequency compared to Danish controls. The MITF p.E318K variant similarly occurred at an approximately three-fold higher frequency in melanoma cases than controls. To conclude, we propose that mutation screening of CDKN2A and CDK4 in Denmark should predominantly be performed in families with at least 3 cases of CM. In addition, we recommend that testing of BAP1 should not be conducted routinely in CM families but should be reserved for families with CM and uveal melanoma, or mesothelioma.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Summary
We present a 3‐year‐old boy with pigmentary mosaicism and persistent intractable infantile spasms due to mosaicism of chromosome 7. Getting the diagnosis of pigmentary mosaicism in a child ...with infantile spasms may not be easy, as most diagnostic work‐up is done in infancy, at a time when skin manifestations can be subtle. We stress the need for a meticulous search for an etiology in cases of infantile spasms. Diagnostic work‐up should include a dermatologic evaluation with skin biopsies for fibroblast culture (and karyotyping) from abnormal pigmented skin areas.
Germ-line mutations in the DNA mismatch repair genes MLH1, MSH2, and MSH6 predispose to the development of colorectal cancer (Lynch syndrome or hereditary nonpolyposis colorectal cancer). These ...mutations include disease-causing frame-shift, nonsense, and splicing mutations as well as large genomic rearrangements. However, a large number of mutations, including missense, silent, and intronic variants, are classified as variants of unknown clinical significance.
Intronic MLH1, MSH2, or MSH6 variants were investigated using in silico prediction tools and mini-gene assay to asses the effect on splicing.
We describe in silico and in vitro characterization of nine intronic MLH1, MSH2, or MSH6 mutations identified in Danish colorectal cancer patients, of which four mutations are novel. The analysis revealed aberrant splicing of five mutations (MLH1 c.588 + 5G > A, MLH1 c.677 + 3A > T, MLH1 c.1732-2A > T, MSH2 c.1276 + 1G > T, and MSH2 c.1662-2A > C), while four mutations had no effect on splicing compared to wild type (MLH1 c.117-34A > T, MLH1 c.1039-8 T > A, MSH2 c.2459-18delT, and MSH6 c.3439-16C > T).
In conclusion, we classify five MLH1/MSH2 mutations as pathogenic, whereas four MLH1/MSH2/MSH6 mutations are classified as neutral. This study supports the notion that in silico prediction tools and mini-gene assays are important for the classification of intronic variants, and thereby crucial for the genetic counseling of patients and their family members.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Is MED13L-related intellectual disability a recognizable syndrome? Tørring, Pernille Mathiesen; Larsen, Martin Jakob; Brasch-Andersen, Charlotte ...
European journal of medical genetics,
February 2019, 2019-Feb, 2019-02-00, 20190201, Letnik:
62, Številka:
2
Journal Article
Recenzirano
Odprti dostop
MED13L-related intellectual disability is characterized by moderate intellectual disability (ID), speech impairment, and dysmorphic facial features. We present 8 patients with MED13L-related ...intellectual disability and review the literature for phenotypical and genetic aspects of previously described patients.
In the search for genetic aberrations in individuals with ID, two of the patients were identified by chromosomal microarray analysis, and five by exome sequencing. One of the individuals, suspected of MED13L-related intellectual disability, based on clinical features, was identified by Sanger sequencing.
All 8 individuals had de novo MED13L aberrations, including two intragenic microdeletions, two frameshift, three nonsense variants, and one missense variant. Phenotypically, they all had intellectual disability, speech and motor delay, and features of the mouth (open mouth appearance, macroglossia, and/or macrostomia). Two individuals were diagnosed with autism, and one had autistic features. One had complex congenital heart defect, and one had persistent foramen ovale. The literature was reviewed with respect to clinical and dysmorphic features, and genetic aberrations.
Even if most clinical features of MED13L-related intellectual disability are rather non-specific, the syndrome may be suspected in some individuals based on the association of developmental delay, speech impairment, bulbous nasal tip, and macroglossia, macrostomia, or open mouth appearance.
Raised plasma triglycerides (TGs) and nonesterified fatty acid (NEFA) concentrations are thought to play a role in the pathogenesis of insulin-resistant diabetes. We report on two sisters with ...extreme hypertriglyceridemia and overt diabetes, in whom surgical normalization of TGs cured the diabetes. In all of the family members (parents, two affected sisters, ages 18 and 15 years, and an 11-year-old unaffected sister), we measured oral glucose tolerance, insulin sensitivity (by the euglycemic-hyperinsulinemic clamp technique), substrate oxidation (indirect calorimetry), endogenous glucose production (by the 6,6-2H2glucose technique), and postheparin plasma lipoprotein lipase (LPL) activity. In addition, GC-clamped polymerase chain reaction-amplified DNA from the promoter region and the 10 coding LPL gene exons were screened for nucleotide substitution. Two silent mutations were found in the father's exon 4 (Glu118 Glu) and in the mother's exon 8 (Thr361 Thr), while a nonsense mutation (Ser447 Ter) was detected in the mother's exon 9. Mutations in exons 4 and 8 were inherited by the two affected girls. At 1-2 years after the appearance of hyperchylomicronemia, both sisters developed hyperglycemia with severe insulin resistance. Because medical therapy (including high-dose insulin) failed to reduce plasma TGs or control glycemia, lipid malabsorption was surgically induced by a modified biliopancreatic diversion. Within 3 weeks of surgery, plasma TGs and NEFA and cholesterol levels were drastically lowered. Concurrently, fasting plasma glucose levels fell from 17 to 5 mmol/l (with no therapy), while insulin-stimulated glucose uptake, oxidation, and storage were all markedly improved. Throughout the observation period, plasma TG levels were closely correlated with both plasma glucose and insulin concentrations, as measured during the oral glucose tolerance test. These cases provide evidence that insulin-resistant diabetes can be caused by extremely high levels of TGs.
The genetic background of familial, late-onset colorectal cancer (CRC) (i.e., onset > age 50 years) has not been studied as thoroughly as other subgroups of familial CRC, and the proportion of ...families with a germline genetic predisposition to CRC remains to be defined. To define the contribution of known or suggested CRC predisposition genes to familial late-onset CRC, we analyzed 32 well-established or candidate CRC predisposition genes in 75 families with late-onset CRC. We identified pathogenic or likely pathogenic variants in five patients in
MSH6
(
n
= 1),
MUTYH
(monoallelic;
n
= 2) and
NTHL1
(monoallelic;
n
= 2). In addition, we identified a number of variants of unknown significance in particular in the lower penetrant Lynch syndrome-associated mismatch repair (MMR) gene
MSH6
(
n
= 6). In conclusion, screening using a comprehensive cancer gene panel in families with accumulation of late-onset CRC appears not to have a significant clinical value due to the low level of high-risk pathogenic variants detected. Our data suggest that only patients with abnormal MMR immunohistochemistry (IHC) or microsatellite instability (MSI) analyses, suggestive of Lynch syndrome, or a family history indicating another cancer predisposition syndrome should be prioritized for such genetic evaluations. Variants in
MSH6
and
MUTYH
have previously been proposed to be involved in digenic or oligogenic hereditary predisposition to CRC. Accumulation of variants in
MSH6
and monoallelic, pathogenic variants in
MUTYH
in our study indicates that digenic or oligogenic inheritance might be involved in late-onset CRC and warrants further studies of complex types of inheritance.
Mowat–Wilson Syndrome is a recently delineated mental retardation syndrome usually associated with multiple malformations and a recognizable facial phenotype caused by defects of the transcriptional ...repressor
ZFHX1B. To address the question of clinical and mutational variability, we analysed a large number of patients with suspected Mowat–Wilson Syndrome (MWS). Without prior knowledge of their mutational status, 70 patients were classified into “typical MWS”, “ambiguous” and “atypical” groups according to their facial phenotype. Using FISH, qPCR and sequencing,
ZFHX1B deletions, splice site or truncating mutations were detected in all 28 patients classified as typical MWS. No
ZFHX1B defect was apparent in the remaining 15 cases with ambiguous facial features or in the 27 atypical patients. Genotype–phenotype analysis confirmed that
ZFHX1B deletions and stop mutations result in a recognizable facial dysmorphism with associated severe mental retardation and variable malformations such as Hirschsprung disease and congenital heart defects. Our findings indicate that structural eye anomalies such as microphthalmia should be considered as part of the MWS spectrum. We also show that agenesis of the corpus callosum and urogenital anomalies (especially hypospadias) are significant positive predictors of a
ZFHX1B defect. Based on our observation of affected siblings and the number of MWS cases previously reported, we suggest a recurrence risk of around 1%. The lack of missense mutations in MWS and MWS-like patients suggests there may be other, as yet unrecognized phenotypes, associated with missense mutations of this transcription factor.
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