Colorectal cancer risk in families with Birt-Hogg-Dubé syndrome increased

[Genetic diffuse cystic lung disease in adults]

Multiple cystic lung diseases comprise a wide range of various diseases, some of them of genetic origin. Lymphangioleiomyomatosis (LAM) is a disease occurring almost exclusively in women, sporadically or in association with tuberous sclerosis complex (TSC). Patients with LAM present with lymphatic complications, renal angiomyolipomas and cystic lung disease responsible for spontaneous pneumothoraces and progressive respiratory insufficiency. TSC and LAM have been ascribed to mutations in TSC1 or TSC2 genes. Patients with TSC are variably affected by cutaneous, cognitive and neuropsychiatric manifestations, epilepsy, cerebral and renal tumors, usually of benign nature. Birt-Hogg-Dubé syndrome is caused by mutations in FLCN encoding folliculin. This syndrome includes lung cysts of basal predominance, cutaneous fibrofolliculomas and various renal tumors. The main complications are spontaneous pneumothoraces and renal tumors requiring systematic screening. The mammalian target of rapamycin (mTOR) pathway is involved in the pathophysiology of TSC, sporadic LAM and Birt-Hogg-Dubé syndrome. MTOR inhibitors are used in LAM and in TSC while Birt-Hogg-Dubé syndrome does not progress towards chronic respiratory failure. Future challenges in these often under-recognized diseases include the need to reduce the delay to diagnosis, and to develop potentially curative treatments. In France, physicians can seek help from the network of reference centers for the diagnosis and management of rare pulmonary diseases.

Colon adenocarcinoma and Birt-Hogg-Dubé syndrome in a young patient: case report and exploration of pathologic implications

Birt-Hogg-Dubé syndrome (BHD) is an autosomal dominant disorder caused by germline mutations in the folliculin gene (FLCN) that result in the functional loss of the tumor suppressor folliculin. It is classically associated with cutaneous hamartomas, pulmonary cysts with spontaneous pneumothorax, and various renal cancers. In this case, we present a patient initially diagnosed with chromophobe renal cell carcinoma and subsequently found to have colorectal cancer (CRC). The presence of two separate malignancies in a young patient with a strong family history of CRC (father and paternal grandfather) led to genetic testing, which revealed an FLCN c.1177-5_1177-3del mutation, and a diagnosis of BHD was made. Out of the more than 300 known unique mutations of the FLCN coding region, the c.1285dupC mutation on exon 11 has been the only one convincingly associated with CRC thus far. While larger cohort studies are needed to further clarify this association, we present the first patient with CRC to our knowledge with an FLCN c.1177-5_1177-3del mutation and loss of heterozygosity implicating it as an initiating factor in tumorigenesis. We further explore the studies supporting and refuting the connection between BHD and CRC and highlight the molecular signaling pathways that may play a role in pathogenesis.

A Novel FLCN Variant in a Suspected Birt-Hogg-Dubè Syndrome Patient

Subjects with pathogenic (PV) and likely pathogenic (LPV) FLCN variants have an increased risk of manifesting benign and malignant disorders that are related to Birt-Hogg-Dubé syndrome (BHDS): an autosomal dominantly inherited disorder whose severity can vary significantly. Renal cell carcinoma (RCC) development in BHD (Birt-Hogg-Dubé) patients has a very high incidence; thus, identifying this rare syndrome at early stages and preventing metastatic spread is crucial. Over the last decade, the advancement of Next Generation Sequencing (NGS) and the implementation of multigene panels for hereditary cancer syndromes (HCS) have led to a subsequent focus on additional genes and variants, including those of uncertain significance (VUS). Here, we describe a novel FLCN variant observed in a subject manifesting disorders that were suspected to be related to BHDS and with a family history of multiple cancers.

Exons 1-3 deletion in FLCN is associated with increased risk of pneumothorax in Chinese patients with Birt-Hogg-Dubé syndrome

BACKGROUND

The pathogenic variants responsible for Birt-Hogg-Dubé syndrome (BHDS) in folliculin (FLCN) gene mostly consist of point mutations. Although large intragenic deletions/duplications have been reported in several case reports, the relationship between large intragenic deletions/duplications and phenotype in BHDS remains unclear.

METHODS

We retrospectively identified and reviewed patients with a large intragenic deletion spanning exons 1-3 and analyzed their phenotypic features to compare with those of point mutation carriers in our hospital from January 1, 2017 to August 31, 2022.

RESULTS

Twenty unique point mutations (including 4 novel mutations) were detected in 62 patients from 45 families (90%). Exons 1-3 deletion were identified in 8 patients from 5 families (10%) that resided in the same region, Feidong County of Anhui Province, China. Breakpoint analysis indicated that all the deletion breakpoints were flanked by Alu repeats. The prevalence of exons 1-3 deletion carriers in Feidong County was 8.1-times higher than that for BHDS in Anhui Province, suggesting a clustered phenomenon of exons 1-3 deletion. Significantly increased risk of pneumothorax was observed in those with exons 1-3 deletion compared with point mutations (91% vs. 58%, p value 0.047). The risk of renal cancer may be higher in those with exons 1-3 deletion than for those with point mutations (18% vs. 4%, p > 0.05).

CONCLUSIONS

Large intragenic deletion of exons 1-3 in FLCN was identified as a local aggregation phenomenon in Feidong County, China, and was associated with a significantly higher risk of pneumothorax compared to those with point mutations.

Hydropneumothorax as a Presentation of Birt-Hogg-Dubé Syndrome

Birt-Hogg-Dubé syndrome (BHDS) is a rare genetic disorder characterized by cutaneous, pulmonary, and renal manifestations. We present a unique case in which a combination of multiple chronic illnesses, genetic testing, and significant family history led to a diagnosis of BHDS. A 72-year-old male patient presented to their primary care physician with a persistent cough of four months and was admitted to the emergency department after the discovery of a left hydropneumothorax. The patient's medical history was significant for recurrent spontaneous bilateral pneumothoraces diagnosed over 20 years ago, chronic obstructive pulmonary disease (COPD), and many other systemic illnesses. A combination of the patient's significant past medical and family history led to a diagnosis of BHDS. Genetic testing was also done to confirm the diagnosis. Despite benign skin lesions being the most common finding, they are not always present, as seen in our case, which can result in missed diagnosis. Due to the autosomal dominant nature of BHDS, it is vital to make an accurate diagnosis to allow for proper genetic counseling, as the development of renal cancer is the leading cause of mortality.

Phaeochromocytoma in a patient with a Birt-Hogg-Dubé syndrome phenotype

A case of phaeochromocytoma in a female patient in her 50s with phenotypical expressions for the rare Birt-Hogg-Dubé (BHD) syndrome is presented. Whether this is an incidental finding or that there is a composite relationship between these two entities remains to be fully described. Less than 10 cases reporting likely association of BHD syndrome with adrenal tumours have been reported in the literature to date.

Birt-Hogg-Dubé syndrome: Another mTOR phenomenon

Birt-Hogg-Dubé syndrome is an uncommon autosomal dominant systemic disorder with cutaneous findings notable for fibrofolliculomas or trichodiscomas on the scalp, face, neck, and trunk. These cutaneous signs are associated with bilateral renal cell carcinoma, benign renal cysts, pulmonary cysts, and spontaneous pneumothorax. Given its autosomal dominant inheritance pattern, the successful diagnosis of Birt-Hogg-Dubé syndrome (BHDS) may elucidate a diagnosis in family members. BHDS results from a mutation in the FLCN gene encoding the folliculin protein, a transcriptional regulator of the mammalian target of rapamycin signaling pathway. Like tuberous sclerosis, BHDS's clinical features may subside with the use of oral rapamycin for mammalian target of rapamycin inhibition, a theoretical concept meriting exploration. Although its prevalence in the general population has been estimated at 2 cases per million, BHDS has been detected in a few patients from the nearby Portuguese-lineage quarter of the city of Newark, a disproportionate prevalence possibly explained by the founder effect.

Delayed diagnosis of Birt-Hogg-Dubé syndrome might be aggravated by gender bias

BACKGROUND

Birt-Hogg-Dubé syndrome is a rare genetic tumor syndrome characterized by renal cell cancer, lung bullae, pneumothorax, and fibrofolliculoma. Patients with such orphan tumor disorders are at risk of not receiving a timely diagnosis. In the present, gender-sensitive study, we analyzed the delay between onset of symptoms and diagnosis of Birt-Hogg-Dubé syndrome.

METHODS

Clinical data of 158 patients from 91 unrelated families were collected. FLCN mutation testing was performed in index patients and family members.

FINDINGS

The occurrence of the first symptom (fibrofolliculoma, pneumothorax or renal cell cancer) was rarely followed by a timely diagnosis of Birt-Hogg-Dubé syndrome and did so significantly less often in female (1.3%) compared to male (11.4%) patients (chi-square 6.83, p-value 0.009). Only 17 out of 39 renal cell cancers (7/17 female, 10/22 male patients) were promptly recognized as a symptom of Birt-Hogg-Dubé syndrome. Patients in which renal cell cancer was initially not recognized as a symptom of Birt-Hogg-Dubé syndrome waited 9.7 years (females SD 9.2, range 1-29) and 8.8 years (males, SD 4.1, range 2-11) for their diagnosis, respectively. Four (three female, one male) patients developed renal cell cancer twice before the genetic tumor syndrome was diagnosed. The delay between fibrofolliculoma or pneumothorax as a first symptom and diagnosis of Birt-Hogg-Dubé syndrome was considerable but not significantly different between females and males (18.1/17.19 versus 16.1/18.92 years). Furthermore, 73 patients were only diagnosed due to family history (delay 15.1 years in females and 17.4 years in males).

INTERPRETATION

The delay between onset of symptoms and diagnosis of Birt-Hogg-Dubé syndrome can be substantial and gender-dependent, causing considerable health risks for patients and their families. It is therefore important to create more awareness of Birt-Hogg-Dubé syndrome and resolve gender biases in diagnostic work-up.

FUNDING

None declared.

Adrenal Cortical Carcinoma and Additional Rare Pathologic Findings in Multi-Organs in a Birt-Hogg-Dubé Syndrome Patient: With an Emphasis on the Molecular Characteristics of Adrenal Cortical Carcinoma

Birt-Hogg-Dubé (BHD) syndrome is a rare autosomal dominant disorder caused by germline alterations in the FLCN gene. We report a 38-year-old man with BHD syndrome presenting with multiple rare pathologic findings involving various organs, including adrenal cortical carcinoma (ACC). Initially, he presented with severe cholestatic jaundice and was found to have a 25 cm left adrenal mass with radiologic evidence of lung metastases, which was diagnosed as ACC on resection. Concurrently, pigmented, bile-stained granular casts were present within the kidney and diffuse cholestasis of the liver consistent with Stauffer syndrome was identified. Subsequent staging workup detected a 1.2 cm tubulovillous adenoma in the distal ascending colon and an incidental 1.2 cm thyroid nodule. Germline genetic testing revealed a pathogenic FLCN c.1285dup. Targeted DNA next generation sequencing of ACC revealed FLCN c.1285dup, IDH2 c.5332C>T, PRKAR1A c.1074del, and PDGFRB c.3282C>A and concurrent transcriptomic analysis demonstrated VEGFA overexpression. Fourteen months after resection, follow-up computerized tomography (CT) identified the progression of lung metastases and chemotherapy with etoposide doxorubicin and cisplatin was initiated. Here, we report the first ACC with the molecular characteristics in a BHD syndrome patient, although 5 adrenal lesions, including ACC, adenomas or neoplasm with malignant potential due to higher Ki67 labelling index, have been reported in the literature and no somatic analysis in these tumors were performed. Despite the rarity, our case potentially expands the tumor spectrum of BHD patients, helps to solidify possible association with adrenal cortical tumors and reiterates the value of genetic counseling in patients with ACC.

Birt-Hogg-Dubé syndrome encountered at rare lung disease clinic in Anhui province, China

Background

Diagnosis of rare diseases remains a challenge in China. We describe our experience with Birt-Hogg-Dubé syndrome (BHDS) encountered at a Rare Lung Disease Clinic recently established in China.

Methods

After the first patient with BHDS was recognized in 2017, a Rare Lung Disease Clinic with a multidisciplinary team of specialists was established. We retrospectively analyzed the data of consecutive patients with BHDS encountered from inception to December 2021.

Results

There were 1, 1, 15, 12 and 21 cases with BHDS diagnosed from year 2017 to 2021, respectively. All 50 patients (34 women) were of Han race with a mean age of 47.4 years. The common manifestations were pulmonary cysts (98%), pneumothorax (54%) and skin lesions (68%). Renal cancer was detected in two patients and renal angiomyolipoma in four other patients. The main presentations leading to diagnosis were pneumothorax (42%), family screening (36%), and lung cysts identified on radiologic imaging (20%). The average delay in diagnosis was 8.3 years, and 4.7 years in patients with only pulmonary cysts. The most frequent pathogenic variant was c.1285del/dup on exon 11 (23%) among 44 patients confirmed by genetic testing. Renal cancer has not been found on follow-up surveillance thus far.

Conclusions

Increasing number of patients with BHDS are being recognized in China, facilitated by establishment of a Rare Lung Disease Clinic. Pulmonary cysts and pneumothorax were commonly encountered features, but skin lesions appeared to be more prevalent in Chinese subjects than previously reported in other Asian countries.

Case Report: A BRCA2 Mutation Identified Through Next-Generation Sequencing in a Birt–Hogg–Dubè Syndrome Family

Birt–Hogg–Dubé syndrome (BHDS) is a rare autosomal dominant inherited disorder caused by a mutation in folliculin (FLCN) gene transmitted via germline autosomal dominant pattern. Patients with this syndrome have an increased susceptibility to renal cell carcinoma, lung cysts, spontaneous pneumothorax, and benign skin hamartomas, and its diagnosis is not easy and consequently underestimated. Several mutations have been identified in FLCN gene, among which the majority of alterations are frameshift (insertion/deletion), nonsense, or splice-site mutations that generally produce unfunctional truncated FLCN proteins. Our aim is to present a case of a BHDS family whose proband is a 56-year-old patient who has been experiencing multiple disorders, has an FLCN genetic mutation, and has also been identified to have a pathogenic variant in BRCA2 gene. Our further purpose is to emphasize the importance of the next-generation sequencing (NGS) approach to identify potential multiple germline mutations in complex and rare oncologic disorders, allowing strict and more targeted cancer screening programs.

Seventh BHD international symposium: recent scientific and clinical advancement

The 7th Birt-Hogg-Dubé (BHD) International Symposium convened virtually in October 2021. The meeting attracted more than 200 participants internationally and highlighted recent findings in a variety of areas, including genetic insight and molecular understanding of BHD syndrome, structure and function of the tumor suppressor Folliculin (FLCN), therapeutic and clinical advances as well as patients' experiences living with this malady.