Atypical ADPKD Due to a DNAJB11 Pathogenic Variant: An Educational Case Report.

Rationale: Due to next-generation sequencing, variants in new genes such as DNAJB11 are recently being identified as causing atypical autosomal dominant polycystic kidney disease (ADPKD). It is important to describe phenotypes associated with these variants in order to increase awareness among clinicians, especially since genetic variability affects ADPKD severity. Presenting Concerns of the Patient: We describe a 55-year-old female patient of Haitian origin who presented with slowly deteriorating kidney function, microscopic hematuria, proteinuria, enlarged kidneys with innumerable small cysts, and a family history of chronic kidney disease and cysts. The phenotype was atypical for ADPKD caused by PKD1 or PKD2 variants, since cysts were of small size, kidneys were only moderately enlarged, and the patient had no extra-renal involvement suggestive of typical ADPKD such as liver cysts, pancreatic cysts, cranial aneurysms, or cardiac abnormalities. Diagnoses: A panel of genes was analyzed by next-generation massive sequencing techniques, including DNAJB11, DZIP1L, GANAB, HNF1B, PKD1, PKD2, and PKHD1. Genetic testing revealed a heterozygous variant in the DNAJB11 gene (c.123 dup), which is predicted to result in premature protein termination (p. Lys42*) and was classified by the laboratory as likely pathogenic. Interventions: She was treated with candesartan 16 mg once daily to address her proteinuria. Outcomes: At the time of the most recent follow-up, her proteinuria has increased, and her kidney function continues to slowly deteriorate. Teaching Points: DNAJB11 variants are a rare cause of atypical ADPKD. It is important to recognize the clinical features that help distinguish DNAJB11 from PKD1 and PKD2 variants. Atypical ADPKD due to DNAJB11 variants is usually characterized by small cysts, normal kidney size, proteinuria, progressive chronic kidney disease, and phenotypic overlap with autosomal dominant tubulointerstitial kidney disease (ADTKD). It may, however, present itself with enlarged kidneys as was seen in our patient. Genetic testing should be offered whenever a patient presents atypical features of ADPKD, which also requires increased awareness among clinicians regarding the various phenotypes of atypical ADPKD.

Justification: Grâce au séquençage de nouvelle génération, on a récemment identifié des variants de nouveaux gènes tels que DNAJB11 qui causeraient une forme atypique de polykystose rénale autosomique dominante (PKRAD). Afin de sensibiliser davantage les cliniciens, il est important de décrire les phénotypes associés à ces variants, d'autant plus qu'on sait que la variabilité génétique affecte la gravité de la PKRAD. Présentation du cas: Nous décrivons le cas d'une patiente de 55 ans d'origine haïtienne qui présentait une lente détérioration de la fonction rénale, une hématurie microscopique, une protéinurie et des reins avec d'innombrables petits kystes. La patiente avait également des antécédents familiaux de néphropathie et de kystes. Le phénotype était atypique pour une PKRAD causée par les variants PKD1 ou PKD2, car les kystes étaient petits, que la taille des reins n'était que modérément augmentée et qu'elle ne présentait aucune atteinte extra-rénale suggérant une PKRAD typique tels que des kystes hépatiques, des kystes pancréatiques, des anévrismes crâniens ou des anomalies cardiaques. Diagnostic: Un groupe de gènes a été analysé par des techniques de séquençage massif de nouvelle génération, notamment les gènes DNAJB11, DZIP1L, GANAB, HNF1B, PKD1, PKD2 et PKHD1. Le dépistage génétique a révélé un variant hétérozygote dans le gène DNAJB11 (c.123 dup), qui est prédite comme entraînant une terminaison protéique prématurée (p.Lys42*) et qui a été classé par le laboratoire comme étant probablement pathogène. Interventions: La patiente a reçu 16 mg de candesartan une fois par jour pour traiter sa protéinurie. Résultats: Lors du plus récent suivi, la protéinurie avait augmenté et la fonction rénale avait continué de se détériorer lentement. Enseignements tirés: Les variants de DNAJB11 sont une cause rare de PKRAD atypique. Il est important de reconnaître les caractéristiques cliniques qui aident à distinguer les variants de DNAJB11 des variants PKD1 et PKD2. La PKRAD atypique due à des variants du gène DNAJB11 est généralement caractérisée par de petits kystes, des reins de taille normale, une protéinurie, une insuffisance rénale chronique progressive et un chevauchement phénotypique avec la néphropathie tubulo-interstitielle autosomique dominante. Elle peut cependant se présenter avec des reins de taille augmentée, comme on l'a vu chez cette patiente. Le dépistage génétique devrait être offert dès qu'un patient présente des caractéristiques de PKRAD atypique, ce qui nécessite également une sensibilisation accrue des cliniciens aux divers phénotypes de la PKRAD atypique.

Molecular Genetic Characteristics of FANCI, a Proposed New Ovarian Cancer Predisposing Gene.

FANCI was recently identified as a new candidate ovarian cancer (OC)-predisposing gene from the genetic analysis of carriers of FANCI c.1813C>T; p.L605F in OC families. Here, we aimed to investigate the molecular genetic characteristics of FANCI, as they have not been described in the context of cancer. We first investigated the germline genetic landscape of two sisters with OC from the discovery FANCI c.1813C>T; p.L605F family (F1528) to re-affirm the plausibility of this candidate. As we did not find other conclusive candidates, we then performed a candidate gene approach to identify other candidate variants in genes involved in the FANCI protein interactome in OC families negative for pathogenic variants in BRCA1, BRCA2, BRIP1, RAD51C, RAD51D, and FANCI, which identified four candidate variants. We then investigated FANCI in high-grade serous ovarian carcinoma (HGSC) from FANCI c.1813C>T carriers and found evidence of loss of the wild-type allele in tumour DNA from some of these cases. The somatic genetic landscape of OC tumours from FANCI c.1813C>T carriers was investigated for mutations in selected genes, copy number alterations, and mutational signatures, which determined that the profiles of tumours from carriers were characteristic of features exhibited by HGSC cases. As other OC-predisposing genes such as BRCA1 and BRCA2 are known to increase the risk of other cancers including breast cancer, we investigated the carrier frequency of germline FANCI c.1813C>T in various cancer types and found overall more carriers among cancer cases compared to cancer-free controls (p = 0.007). In these different tumour types, we also identified a spectrum of somatic variants in FANCI that were not restricted to any specific region within the gene. Collectively, these findings expand on the characteristics described for OC cases carrying FANCI c.1813C>T; p.L605F and suggest the possible involvement of FANCI in other cancer types at the germline and/or somatic level.

A comparative analysis of RAS variants in patients with disorders of somatic mosaicism.

PURPOSE: RAS genes (HRAS, KRAS, and NRAS) are commonly found to be mutated in cancers, and activating RAS variants are also found in disorders of somatic mosaicism (DoSM). A survey of the mutational spectrum of RAS variants in DoSM has not been performed. METHODS: A total of 938 individuals with suspected DoSM underwent high-sensitivity clinical next-generation sequencing-based testing. We investigated the mutational spectrum and genotype-phenotype associations of mosaic RAS variants. RESULTS: In this article, we present a series of individuals with DoSM with RAS variants. Classic hotspots, including Gly12, Gly13, and Gln61 constituted the majority of RAS variants observed in DoSM. Furthermore, we present 12 individuals with HRAS and KRAS in-frame duplication/insertion (dup/ins) variants in the switch II domain. Among the 18.3% individuals with RAS in-frame dup/ins variants, clinical findings were mainly associated with vascular malformations. Hotspots were associated with a broad phenotypic spectrum, including vascular tumors, vascular malformations, nevoid proliferations, segmental overgrowth, digital anomalies, and combinations of these. The median age at testing was higher and the variant allelic fraction was lower in individuals with in-frame dup/ins variants than those in individuals with mosaic RAS hotspots. CONCLUSION: Our work provides insight into the allelic and clinical heterogeneity of mosaic RAS variants in nonmalignant conditions.

Amyloid Deposits in a Functionally Unicuspid Stenotic Aortic Valve.

Amyloidosis concomitant to aortic stenosis usually occurs with myocardial infiltration by the transthyretin protein. To our knowledge, this is the first report of localized amyloidosis of indeterminate type in a severely calcified and functionally unicuspid aortic valve. Isolated dystrophic valvular amyloidosis is believed to be related to fibrocalcific valve disease. In light of the literature on this topic, the present case raises new hypotheses on pathophysiology and further supports the contributory role of unusual non-tricuspid valve morphology in the development of dystrophic amyloid, likely secondary to altered hemodynamic stress.

Une amyloïdose associée à une sténose aortique survient généralement avec infiltration du myocarde par la protéine transthyrétine. Le cas que nous décrivons est, à notre connaissance, le premier cas rapporté d'amyloïdose localisée de type indéterminé dans une valve aortique sévèrement calcifiée et fonctionnellement unicuspide. L'amyloïdose valvulaire dystrophique isolée serait liée à l'atteinte fibrocalcique de la valve. À la lumière de la littérature à ce sujet, le cas décrit ici permet de soulever de nouvelles hypothèses physiopathologiques et appuie le lien entre une morphologie valvulaire inhabituelle (non tricuspide) et l'apparition de substances amyloïdes dystrophiques, probablement secondaire à une altération des contraintes hémodynamiques.

Genetic Dissection of Primary Aldosteronism in a Patient With MEN1 and Ipsilateral Adrenocortical Carcinoma and Adenoma.

BACKGROUND: Adrenal tumors are found in up to 40% of patients with multiple endocrine neoplasia type 1 (MEN1). However, adrenocortical carcinomas (ACC) and primary aldosteronism (PA) are rare in MEN1. CASE: A 48-year-old woman known to have primary hyperparathyroidism and hypertension with hypokalemia was referred for a right complex 8-cm adrenal mass with a 38.1 SUVmax uptake on 18F-FDG PET/CT. PA was confirmed by saline suppression test (aldosterone 1948 pmol/L-1675 pmol/L; normal range [N]: <165 post saline infusion) and suppressed renin levels (<5 ng/L; N: 5-20). Catecholamines, androgens, 24-hour urinary cortisol, and pituitary panel were normal. A right open adrenalectomy revealed a concomitant 4-cm oncocytic ACC and a 2.3-cm adrenocortical adenoma. Immunohistochemistry showed high expression of aldosterone synthase protein in the adenoma but not in the ACC, supporting excess aldosterone production by the adenoma. GENETIC ANALYSIS: After genetic counseling, the patient underwent genetic analysis of leucocyte and tumoral DNA. Sequencing of MEN1 revealed a heterozygous germline pathogenic variant in MEN1 (c.1556delC, p.Pro519Leufs*40). The wild-type MEN1 allele was lost in the tumoral DNA of both the resected adenoma and carcinoma. Sequencing analysis of driver genes in PA revealed a somatic pathogenic variant in exon 2 of the KCNJ5 gene (c.451G>A, p.Gly151Arg) only in the aldosteronoma. CONCLUSION: To our knowledge, we describe the first case of adrenal collision tumors in a patient carrying a germline pathogenic variant of the MEN1 gene associated with MEN1 loss of heterozygosity in both oncocytic ACC and adenoma and a somatic KCNJ5 pathogenic variant leading to aldosterone-producing adenoma. This case gives new insights on adrenal tumorigenesis in MEN1 patients.

The Genetic and Molecular Analyses of RAD51C and RAD51D Identifies Rare Variants Implicated in Hereditary Ovarian Cancer from a Genetically Unique Population.

To identify candidate variants in RAD51C and RAD51D ovarian cancer (OC) predisposing genes by investigating French Canadians (FC) exhibiting unique genetic architecture. Candidates were identified by whole exome sequencing analysis of 17 OC families and 53 early-onset OC cases. Carrier frequencies were determined by the genetic analysis of 100 OC or HBOC families, 438 sporadic OC cases and 1025 controls. Variants of unknown function were assayed for their biological impact and/or cellular sensitivity to olaparib. RAD51C c.414G>C;p.Leu138Phe and c.705G>T;p.Lys235Asn and RAD51D c.137C>G;p.Ser46Cys, c.620C>T;p.Ser207Leu and c.694C>T;p.Arg232Ter were identified in 17.6% of families and 11.3% of early-onset cases. The highest carrier frequency was observed in OC families (1/44, 2.3%) and sporadic cases (15/438, 3.4%) harbouring RAD51D c.620C>T versus controls (1/1025, 0.1%). Carriers of c.620C>T (n = 7), c.705G>T (n = 2) and c.137C>G (n = 1) were identified in another 538 FC OC cases. RAD51C c.705G>T affected splicing by skipping exon four, while RAD51D p.Ser46Cys affected protein stability and conferred olaparib sensitivity. Genetic and functional assays implicate RAD51C c.705G>T and RAD51D c.137C>G as likely pathogenic variants in OC. The high carrier frequency of RAD51D c.620C>T in FC OC cases validates previous findings. Our findings further support the role of RAD51C and RAD51D in hereditary OC.

Case Review: Whole-Exome Sequencing Analyses Identify Carriers of a Known Likely Pathogenic Intronic BRCA1 Variant in Ovarian Cancer Cases Clinically Negative for Pathogenic BRCA1 and BRCA2 Variants.

Background: Detecting pathogenic intronic variants resulting in aberrant splicing remains a challenge in routine genetic testing. We describe germline whole-exome sequencing (WES) analyses and apply in silico predictive tools of familial ovarian cancer (OC) cases reported clinically negative for pathogenic BRCA1 and BRCA2 variants. Methods: WES data from 27 familial OC cases reported clinically negative for pathogenic BRCA1 and BRCA2 variants and 53 sporadic early-onset OC cases were analyzed for pathogenic variants in BRCA1 or BRCA2. WES data from carriers of pathogenic BRCA1 or BRCA2 variants were analyzed for pathogenic variants in 10 other OC predisposing genes. Loss of heterozygosity analysis was performed on tumor DNA from variant carriers. Results: BRCA1 c.5407-25T>A intronic variant, identified in two affected sisters and one sporadic OC case, is predicted to create a new splice effecting transcription of BRCA1. WES data from BRCA1 c.5407-25T>A carriers showed no evidence of pathogenic variants in other OC predisposing genes. Sequencing the tumor DNA from the variant carrier showed complete loss of the wild-type allele. Conclusions: The findings support BRCA1 c.5407-25T>A as a likely pathogenic variant and highlight the importance of investigating intronic sequences as causal variants in OC families where the involvement of BRCA1 is highly suggestive.

A decade of RAD51C and RAD51D germline variants in cancer.

Defects in DNA repair genes have been extensively associated with cancer susceptibility. Germline pathogenic variants (GPV) in genes involved in homologous recombination repair pathways predispose to cancers arising mainly in the breast and ovary, but also other tissues. The RAD51 paralogs RAD51C and RAD51D were included in this group 10 years ago when germline variants were associated with non-BRCA1/2 familial ovarian cancer. Here, we have reviewed the landscape of RAD51C and RAD51D germline variants in cancer reported in the literature during the last decade, integrating this list with variants identified by in-house patient screening. A comprehensive catalog of 341 variants that have been classified applying ACMG/AMP criteria has been generated pinpointing the existence of recurrent variants in both genes. Recurrent variants have been extensively discussed compiling data on population frequencies and functional characterization if available, highlighting variants that have not been fully characterized yet to properly establish their pathogenicity. Finally, we have complemented this data with relevant information regarding the conservation of mutated residues among RAD51 paralogs and modeling of putative hotspot areas, which contributes to generating an exhaustive update on these two cancer predisposition genes.

A functionally impaired missense variant identified in French Canadian families implicates FANCI as a candidate ovarian cancer-predisposing gene.

BACKGROUND: Familial ovarian cancer (OC) cases not harbouring pathogenic variants in either of the BRCA1 and BRCA2 OC-predisposing genes, which function in homologous recombination (HR) of DNA, could involve pathogenic variants in other DNA repair pathway genes. METHODS: Whole exome sequencing was used to identify rare variants in HR genes in a BRCA1 and BRCA2 pathogenic variant negative OC family of French Canadian (FC) ancestry, a population exhibiting genetic drift. OC cases and cancer-free individuals from FC and non-FC populations were investigated for carrier frequency of FANCI c.1813C>T; p.L605F, the top-ranking candidate. Gene and protein expression were investigated in cancer cell lines and tissue microarrays, respectively. RESULTS: In FC subjects, c.1813C>T was more common in familial (7.1%, 3/42) than sporadic (1.6%, 7/439) OC cases (P = 0.048). Carriers were detected in 2.5% (74/2950) of cancer-free females though female/male carriers were more likely to have a first-degree relative with OC (121/5249, 2.3%; Spearman correlation = 0.037; P = 0.011), suggesting a role in risk. Many of the cancer-free females had host factors known to reduce risk to OC which could influence cancer risk in this population. There was an increased carrier frequency of FANCI c.1813C>T in BRCA1 and BRCA2 pathogenic variant negative OC families, when including the discovery family, compared to cancer-free females (3/23, 13%; OR = 5.8; 95%CI = 1.7-19; P = 0.005). In non-FC subjects, 10 candidate FANCI variants were identified in 4.1% (21/516) of Australian OC cases negative for pathogenic variants in BRCA1 and BRCA2, including 10 carriers of FANCI c.1813C>T. Candidate variants were significantly more common in familial OC than in sporadic OC (P = 0.04). Localization of FANCD2, part of the FANCI-FANCD2 (ID2) binding complex in the Fanconi anaemia (FA) pathway, to sites of induced DNA damage was severely impeded in cells expressing the p.L605F isoform. This isoform was expressed at a reduced level, destabilized by DNA damaging agent treatment in both HeLa and OC cell lines, and exhibited sensitivity to cisplatin but not to a poly (ADP-ribose) polymerase inhibitor. By tissue microarray analyses, FANCI protein was consistently expressed in fallopian tube epithelial cells and only expressed at low-to-moderate levels in 88% (83/94) of OC samples. CONCLUSIONS: This is the first study to describe candidate OC variants in FANCI, a member of the ID2 complex of the FA DNA repair pathway. Our data suggest that pathogenic FANCI variants may modify OC risk in cancer families.

Current gene panels account for nearly all homologous recombination repair-associated multiple-case breast cancer families.

It was hypothesized that variants in underexplored homologous recombination repair (HR) genes could explain unsolved multiple-case breast cancer (BC) families. We investigated HR deficiency (HRD)-associated mutational signatures and second hits in tumor DNA from familial BC cases. No candidates genes were associated with HRD in 38 probands previously tested negative with gene panels. We conclude it is unlikely that unknown HRD-associated genes explain a large fraction of unsolved familial BC.

Whether, when, how, and how much? General public's and cancer patients' views about the disclosure of genomic secondary findings.

BACKGROUND: Data on the modalities of disclosing genomic secondary findings (SFs) remain scarce. We explore cancer patients' and the general public's perspectives about disclosing genomic SFs and the modalities of such disclosure. METHODS: Sixty-one cancer patients (n = 29) and members of the public (n = 32) participated in eight focus groups in Montreal and Quebec City, Canada. They were asked to provide their perspectives of five fictitious vignettes related to medically actionable and non-actionable SFs. Two researchers used a codification framework to conduct a thematic content analysis of the group discussion transcripts. RESULTS: Cancer patients and members of the public were open to receive genomic SFs, considering their potential clinical and personal utility. They believed that the right to know or not and share or not such findings should remain the patient's decision. They thought that the disclosure of SFs should be made mainly in person by the prescribing clinician. Maintaining confidentiality when so requested and preventing genetic discrimination were considered essential. CONCLUSION: Participants in this study welcomed the prospect of disclosing genomic SFs, as long as the right to choose to know or not to know is preserved. They called for the development of policies and practice guidelines that aim to protect genetic information confidentiality as well as the autonomy, physical and psychosocial wellbeing of patients and families.

Small adrenal incidentaloma becoming an aggressive adrenocortical carcinoma in a patient carrying a germline APC variant.

PURPOSE: Recent guidelines on adrenal incidentalomas suggested in patients with an indeterminate adrenal mass and no significant hormone excess that follow up with a repeat noncontrast CT or MRI after 6-12 months may be an option. METHODS: We report the case of a 32-year-old woman who presented with a 2.9 × 1.9 cm left adrenal incidentaloma that was stable in size for 4 years. Ten years later the left adrenal mass was a stage IV adrenocortical carcinoma (ACC). RESULTS: In 2006, a 32-year-old French Canadian woman was referred to endocrinology for a left 2.9 × 1.9 cm incidentally discovered adrenal mass (31 HU). She had normal hormonal investigation. The patient was followed with adrenal imaging and hormonal investigation yearly for 4 years and the lesion stayed stable in size over the 4 years. Ten years later, in 2016, the patient presented with renal colic. Urological CT unexpectedly revealed that the left adrenal mass was now measuring 9 × 8.2 cm and 2 new hepatic lesions were found. Biochemical workup demonstrated hypercorticism and hyperandrogenemia: plasma cortisol after 1 mg overnight DST of 476 nmol/L and DHEA-S of 14.0 µmol/L (N 0.9-6.5). Twenty-four hour urine steroid profiling was consistent with an adrenocortical carcinoma (ACC) co-secreting cortisol, androgens and glucocorticoid precursors. The diagnosis of ACC with hepatic ACC metastases was confirmed at histology. Following genetic analysis, germline heterozygous variant of uncertain significance (VUS) was identified in the exon 16 of the APC gene (c.2414G > A, p.Arg805Gln). Immunohistochemical staining's of the ACC was positive for IGF-2 and cytoplasmic/nuclear ß-catenin staining. CONCLUSIONS: This case illustrates that (1) small adrenal incidentaloma stable in size may evolve to ACC and (2) better genetic characterization of these patients may eventually give clues on this unusual evolution.

Langerhans cell histiocytosis presenting as Crohn's disease: a case report.

PURPOSE: We describe an exceptional case of Langerhans cell histiocytosis (LCH) that presented as Crohn's disease and primary sclerosing cholangitis. METHODS: The patient's clinical, endoscopic, and histologic data from the Centre Hospitalier de l'Universite de Montreal were reviewed, as well as the literature on LCH involving the digestive tract and the liver, with a focus on the similarities with Crohn's disease and primary sclerosing cholangitis. RESULTS: A 39 years-old man first presented with anal fissures and deep punctiform colonic ulcers. Histologic assessment of colon biopsies showed chronic active colitis, consistent with Crohn's disease. Mild cholestasis and endoscopic retrograde cholangiopancreatography (ERCP) showing multiple intra and extrahepatic biliary tract strictures also led to a diagnosis of sclerosing cholangitis. Perianal disease progressed despite conventional treatment with antibiotics and infliximab. Subsequent discovery of non-Langerhans cutaneous xanthogranulomas and panhypopituitarism raised the suspicion of LCH, and a second review of colon biopsies ultimately led to the diagnosis, with the identification of Langerhans cells depicting elongated, irregular nuclei with nuclear grooves as well as immunohistochemical reactivity for S100, CD1a and vimentin. BRAF V600E mutation was detected afterwards by DNA sequencing of a bile duct sample. CONCLUSION: LCH may mimic inflammatory bowel disease (IBD) and must be suspected in the presence of other suggestive clinical signs, or when there is failure of conventional IBD treatment.

Clinical follow-up and breast and ovarian cancer screening of true BRCA1/2 noncarriers: a qualitative investigation.

PURPOSE: Most women from BRCA1/2 mutation-positive families who did not inherit the familial mutation have breast and ovarian cancer risks similar to those of women of the same age in the general population. However, recent studies suggest that some of these noncarriers may exhibit screening practices that may be considered as excessive compared to general population screening guidelines. Reasons for such tendencies remain largely unknown. This study aims to better understand how the implications of a noncarrier status are explained to these women and how their own realization of this status affects their screening behaviors. METHODS: A qualitative study was conducted with five focus groups (n = 28) in Quebec City and Montreal, Canada. RESULTS: Thematic analysis of the discussions highlighted four major themes: (i) acquiring a noncarrier identity takes place progressively; (ii) noncarriers show a range of opinions about screening; (iii) noncarriers have mixed feelings about the follow-up by their physicians and gynecologists; and (iv) noncarriers need more information in a context where genetics progresses ever more rapidly. CONCLUSION: Our results provide novel insights regarding the physician-patient interaction and the organizational aspects of the health-care system that may significantly impact the cancer screening practices of BRCA1/2 noncarriers.Genet Med 18 6, 627-634.