Hermansky-Pudlak Syndrome

Biochemical and structural characterization of Biogenesis of Lysosome-related Organelles Complex-1 (BLOC-1)

Lysosome-related organelles (LROs) play critical roles in diverse cellular processes, and their dysfunction is linked to genetic disorders such as Hermansky-Pudlak Syndrome (HPS). BLOC-1(Biogenesis of Lysosome-related Organelles Complex-1) is a key regulator of LRO biogenesis and intracellular vesicle trafficking. However, the molecular mechanisms governing BLOC-1 assembly and its function remain poorly understood. In this study, we present a biochemical and structural characterization of BLOC-1, revealing a curved, arc-shaped architecture. Our structural model demonstrates that this hetero-octameric complex is composed of two distinct hemicomplexes: BLOC1S2/5/7/8 and BLOC1S1/3/4/6. Cryo-EM 2D classification analysis shows that both hemicomplexes adopt extended rod-like structures but differ in length. The merging of these two hemicomplexes gives rise to BLOC-1's unique arc-like conformation. These findings provide critical insights into the molecular architecture of BLOC-1, advancing our understanding of its role in LRO biogenesis and vesicle trafficking.

A 29-Year-Old Man With Type 2 Hermansky-Pudlak Syndrome and Wolff-Parkinson-White Syndrome: The Hypothesis of a Potential Link Between These Two Conditions

A 29-year-old Moroccan with oculocutaneous albinism presented with a history of exertional dyspnea, recurrent epistaxis, and bacterial infections, raising suspicion of Hermansky-Pudlak syndrome (HPS). Further evaluation revealed neutropenia, impaired platelet function, pulmonary fibrosis, and mild pulmonary hypertension. An ECG identified ventricular pre-excitation with a postero-septal right accessory pathway, consistent with Wolff-Parkinson-White (WPW) syndrome. Genetic testing confirmed a homozygous mutation in the AP3B1 gene and a diagnosis of Type 2 HPS (HPS-2) was made. HPS-2 is an extremely rare disorder, and to our knowledge, the co-occurrence of WPW syndrome has not been previously reported in literature. We propose a potential causal link between these two conditions, as mutations in the AP3B1 gene-which encodes the beta subunit of the adapter protein 3 trafficking complex-result in mistrafficking of transmembrane proteins from the endosomal and trans-Golgi network to lysosomes and endosome-lysosome-related organelles. Specifically, the dysfunction of a transmembrane protein, namely the lysosome-associated membrane protein 2 (LAMP-2), has been implicated in the development of cardiac accessory pathways, as seen in Danon disease. We hypothesize that individuals with HPS-2 may have a genetic predisposition to WPW syndrome, and this hypothesis should be investigated in further studies.

Hermansky-Pudlak syndrome (HPS): a rare genetic interstitial lung disease

Hermansky-Pudlak syndrome pulmonary fibrosis (HPS-PF) is a rare cause of genetic interstitial lung disease (ILD). A man in his 40s who has oculocutaneous albinism (OCA) since birth presented with respiratory failure to the intensive care department. On further evaluation, high-resolution CT was suggestive of non-specific interstitial pneumonia (NSIP). In view of the early age of presentation of ILD and OCA, genetic testing was done, which confirmed the diagnosis of HPS. He was treated with oxygen, steroids and antifibrotics. Lung transplantation is the definitive treatment option, and he is being referred for the same.

Hermansky-Pudlak Syndrome Complicated by Crohn's Disease and Hidradenitis Suppurativa: A Case of Multisystem Immune Dysregulation

Hermansky-Pudlak syndrome (HPS) is a rare autosomal recessive disorder marked by defects in lysosomal function that can manifest with a granulomatous enterocolitis resembling Crohn's disease (CD). We present a 16-year-old adolescent boy with HPS-associated CD and hidradenitis suppurativa (HS), representing one of a few cases of HPS with concurrent CD and HS described in the literature to date. Disease stabilization on combined infliximab and methotrexate highlights potentially shared inflammatory pathways involved in the pathogenesis of HPS-associated CD and HS. Given the rarity and refractory nature of this disease constellation, our case may provide a beneficial treatment strategy for other patients.

The Role of Platelet Dysfunctions in the Pathogenesis of the Hemostatic-Coagulant System Imbalances

Platelet dysfunction plays a critical role in the pathogenesis of various disorders affecting the hemostatic-coagulant system. This review aims to explore the mechanisms by which platelet dysfunctions contribute to the disruption of hemostasis, leading to an increased risk of both thrombosis and bleeding. Platelets, traditionally known for their role in clot formation, can exhibit altered functionality under pathological conditions such as cardiovascular diseases, metabolic disorders, and autoimmune diseases, impacting their interaction with coagulation factors and vascular endothelium. The review discusses the molecular and cellular mechanisms underlying platelet dysfunction, including aberrations in platelet activation, aggregation, and secretion. It also highlights the interplay between platelets and other components of the coagulation cascade, such as fibrinogen and clotting factors, in maintaining vascular integrity. Moreover, the review examines clinical implications, including how platelet dysfunction can be a contributing factor in conditions like deep vein thrombosis, stroke, and disseminated intravascular coagulation (DIC). Finally, current therapeutic approaches targeting platelet dysfunctions, including antiplatelet agents and emerging therapies, are reviewed to provide insights into potential strategies for managing fluid-coagulation system imbalances. This review underscores the importance of a comprehensive understanding of platelet dysfunction to improve diagnosis and treatment of hemostatic disorders.

Hermansky-Pudlak Syndrome Type 1 Presenting with Interstitial Lung Disease: A Report of a Rare Case from Saudi Arabia

BACKGROUND Hermansky-Pudlak syndrome (HPS) is a rare autosomal recessive disorder characterized by oculocutaneous albinism, bleeding diathesis, and potential multi-organ involvement such as pulmonary fibrosis and granulomatous colitis. While its incidence is globally low, it may be under-reported, particularly in regions with high rates of consanguinity, such as the Middle East. By reporting this case, we aim to increase awareness of this condition as well as its association with ILD. CASE REPORT Herein, we present the case of a 48-year-old Saudi man of Arab descent with a 2-year history of progressive exertional dyspnea that recently worsened over the last 6 months, resulting in a Modified Medical Research Council (MMRC) dyspnea scale score increase from 2 to 3. Examination revealed signs consistent with albinism, accompanied by bibasilar end-inspiratory crackles on chest auscultation. Further evaluations revealed CT imaging consistent with non-specific interstitial lung pneumonia pattern (NSIP) with associated precapillary pulmonary hypertension. Notably, the patient exhibited oculocutaneous albinism, prompting consideration of Hermansky-Pudlak syndrome. Genetic testing confirmed an autosomal recessive HPS type 1 variant, a rarity in the Middle East. CONCLUSIONS HPS1 with ILD is rare in Saudi Arabia. This report describes such a case, offering important insight into its clinical presentation. Clinical management entails a multidisciplinary approach, including supportive care, preventive measures, and consideration of lung transplantation for severe cases. Consanguinity and endogamy, which are quite prevalent in the Middle East, probably means there is more prevalence of HPS and HPS-associated ILD than is recognized. Heightened awareness among healthcare providers is paramount for early diagnosis and optimal management of HPS-associated complications.

Emergence of inflammatory fibroblasts with aging in Hermansky-Pudlak syndrome associated pulmonary fibrosis

The longitudinal cellular interactions that drive pulmonary fibrosis are not well understood. To investigate the disease underpinnings associated with fibrosis onset and progression, we generated a scRNA-seq atlas of lungs from young and aged mouse models of multiple subtypes of Hermansky-Pudlak syndrome (HPS), a collection of rare autosomal recessive diseases associated with albinism, platelet dysfunction, and pulmonary fibrosis. We have identified an age-dependent increase in SAA3+ inflammatory lung fibroblasts in HPS mice, including in double-mutant HPS1-2 mice which develop spontaneous fibrosis. HPS1 fibroblasts show increased expression of IL-1R1, whereas alveolar type II epithelial cells from HPS2 mice induce the inflammatory gene signature in co-cultured fibroblasts. scRNA-seq of lung tissue from three HPS1 patients similarly shows the presence of inflammatory fibroblasts and increased IL1R1 expression on fibroblasts. These data posit complex interactions between dysfunctional epithelial cells, inflammatory fibroblasts, and recruited immune cells, suggesting potential opportunities for mitigation of the fibrotic cascade.

Oncogenic genodermatoses in paediatric patients with skin of colour: a review

Cutaneous neoplasms are relatively rare in children. Most commonly, skin cancers arise through environmental factors, particularly ultraviolet radiation; thus, age is the most predictive factor in developing cutaneous carcinomas. However, children born with certain genodermatoses are significantly more likely to develop malignancies and must be carefully monitored and treated. Most published data are based mainly on signs and symptoms present in White patients. Therefore, we aim to highlight the cutaneous presentations and relative differences of these genodermatoses among patients with skin of colour, who are underrepresented in medicine. We conducted a literature review of 504 patients presented in 236 published articles. Manuscripts with accessible case reports for children aged ≤ 17 years were included. Patients with skin of colour often present with fewer classical findings and have higher incidences of scarring and dyspigmentation. There is also a higher incidence of consanguinity in affected patients. Providers who are able to recognize nonclassical signs can provide proper management and treatment regimens, potentially bringing outcomes for patients with skin of colour more in line with those of White children.

Pathogenesis and Therapy of Hermansky-Pudlak Syndrome (HPS)-Associated Pulmonary Fibrosis

Hermansky-Pudlak syndrome (HPS)-associated pulmonary fibrosis (HPS-PF) is a progressive lung disease that is a major cause of morbidity and mortality in HPS patients. Previous studies have demonstrated that the HPS proteins play an essential role in the biogenesis and function of lysosome-related organelles (LROs) in alveolar epithelial type II (AT2) cells and found that HPS-PF is associated with dysfunction of AT2 cells and abnormal immune reactions. Despite recent advances in research on HPS and the pathology of HPS-PF, the pathological mechanisms underlying HPS-PF remain poorly understood, and no effective treatment has been established. Therefore, it is necessary to refresh the progress in the pathogenesis of HPS-PF to increase our understanding of the pathogenic mechanism of HPS-PF and develop targeted therapeutic strategies. This review summarizes the recent progress in the pathogenesis of HPS-PF provides information about the current treatment strategies for HPS-PF, and hopefully increases our understanding of the pathogenesis of HPS-PF and offers thoughts for new therapeutic interventions.

Impairment of Renal Function in Hermansky-Pudlak Syndrome

INTRODUCTION

Hermansky-Pudlak syndrome (HPS) is a rare autosomal recessive disorder characterized by defective biogenesis of lysosome-related organelles. The genetic types of HPS are associated with a spectrum of multisystemic clinical manifestations. Phenotypic features of HPS type 1 (HPS-1) or HPS-4, which are associated with defects in biogenesis of lysosome-related organelles complex-3 (BLOC-3), are generally more severe than those of HPS-3, HPS-5, or HPS-6, which are associated with defects in BLOC-2. A paucity of information is available about renal impairment in HPS. The objective of this study is to expand the understanding of kidney disease in HPS.

METHODS

Medical records and clinical data of patients with HPS evaluated at the National Institutes of Health Clinical Center from 1995 to 2020 were retrospectively reviewed. For patients with more than one visit, the most recent renal function and urinalysis tests were analyzed. Estimated glomerular filtration rate (eGFR) was calculated using standard equations (i.e., Chronic Kidney Disease Epidemiology Collaboration, Modification of Diet in Renal Disease). Kidney tissue sections from 5 patients with HPS-1 and 1 patient with HPS-6 were examined.

RESULTS

Records from 205 adults and 52 children with HPS were reviewed. Calculated eGFR of adult patients with different HPS types differed significantly, and calculated eGFR of pediatric and adult patients with BLOC-3 disorders was significantly lower than that of patients with BLOC-2 disorders. Linear regression analysis showed that renal function progressively decreases with age in patients with BLOC-3 or BLOC-2 disorders, but the rate of decline was more rapid in patients with BLOC-3 disorders compared to patients with BLOC-2 disorders. In adult patients with HPS-1, glucosuria was found in 4%, proteinuria in 12%, hematuria in 15%, high levels of urinary β2MG in 24%, and elevated urinary albumin to creatinine ratios in 9%. Histological examination of kidney tissue showed accumulation of intracellular deposits of ceroid lipofuscin in proximal renal tubular epithelial cells in patients with HPS-1. There was no evidence of fibrosis, and glomeruli, distal renal tubular epithelial cells, and interstitial regions appeared histologically normal.

CONCLUSION

Mild impairment of renal function is a feature of HPS. Kidneys of patients with HPS-1 contain proximal renal tubular intracellular deposits and no histologic evidence of fibrosis. Consistent with other manifestations of HPS, the phenotype of renal impairment is relatively more pronounced in patients with BLOC-3 disorders than in patients with BLOC-2 disorders. Strategies to avoid nephrotoxicity or renal tubular injury and to protect renal function should be considered for patients with HPS irrespective of age.

Rare interstitial lung diseases: a narrative review

Background and Objective

Interstitial lung diseases (ILDs) encompass over 200 entities. Among them, fibrosing lung diseases, have recently generated special interest due to the emerging therapies for their management. However, it is important to deepen our knowledge of other less prevalent ILD, since many of them are associated with a poor prognosis. This narrative review aims to provide a practical and up-to-date description of some poorly recognized ILD. It covers rare idiopathic interstitial pneumonias and their histologic patterns, genetic disorders with interstitial lung involvement (Hermansky-Pudlak syndrome), and ILD associated with benign proliferation of pulmonary lymphoid tissue, namely follicular bronchiolitis and granulomatous-lymphocytic interstitial lung disease.

Methods

Electronic searches of PubMed and Google Scholar using specific keywords were conducted. Articles underwent screening for relevance, covering review articles, meta-analyses, systematic reviews, case series, prospective studies, society guidelines, editorials in peer-reviewed journals; scientific books on the subject. The data included was limited to English and Spanish publications.

Key Content and Findings

Despite the low prevalence of these diseases, the increased recognition of radiological patterns, pathological features, and diagnostic procedures, have permitted their better characterization. This review highlights epidemiology, clinical presentation, diagnosis, natural history, and treatment.

Conclusions

Lesser-studied ILD represent a diagnostic and therapeutic challenge and can be frequently misdiagnosed. Also, due to the lack of randomized controlled trials, there are no well-established therapeutic options. Further studies or registries are needed to improve accurate diagnosis and management.

Mutational spectrum associated with oculocutaneous albinism and Hermansky-Pudlak syndrome in nine Pakistani families

BACKGROUND

Oculocutaneous albinism (OCA) is a genetically heterogeneous condition that is associated with reduced or absent melanin pigment in the skin, hair, and eyes, resulting in reduced vision, high sensitivity to light, and rapid and uncontrolled eye movements. To date, seventeen genes have been associated with OCA including syndromic and non-syndromic forms of the condition.

METHODS

Whole exome sequencing (WES) was performed to identify pathogenic variants in nine Pakistani families with OCA, with validation and segregation of candidate variants performed using Sanger sequencing. Furthermore, the pathogenicity of the identified variants was assessed using various in-silico tools and 3D protein structural analysis software.

RESULTS

WES identified biallelic variants in three genes explaining the OCA in these families, including four variants in TYR, three in OCA2, and two in HPS1, including two novel variants c.667C > T: p.(Gln223*) in TYR, and c.2009 T > C: p.(Leu670Pro) in HPS1.

CONCLUSIONS

Overall, this study adds further knowledge of the genetic basis of OCA in Pakistani communities and facilitates improved management and counselling services for families suffering from severe genetic diseases in Pakistan.

Hermansky-Pudlak Syndrome: A Rare Congenital Disorder With Interstitial Lung Disease

Hermansky-Pudlak syndrome (HPS) is a genetic multisystemic disorder with oculocutaneous albinism, granulomatous colitis, bleeding diathesis, and pulmonary fibrosis. Multiple subtypes of HPS exist, with certain types having higher predilection for pulmonary fibrosis. This case report focuses on the demonstration of pulmonary imaging findings seen in a patient. Several imaging features overlap with idiopathic pulmonary fibrosis including traction bronchiectasis, pleural and peribronchovascular thickening, and reticulations. This case report highlights the differences seen in lung disease associated with HPS compared to other interstitial lung diseases, in addition to the multi-systemic features of HPS.

Skin cancer-associated genodermatoses in skin of color patients: a review

Skin cancers are associated with a large number of genodermatoses. Existing knowledge and guidelines on the presentations of these genodermatoses focus disproportionately on White patients. Our goal is to identify notable characteristics in location, frequency, and severity of cutaneous findings along with the median age of skin cancers in skin-of-color (SOC) patients with skin-cancer-associated genodermatoses to improve diagnosis rates. We searched for genodermatoses on six databases. Each case report or case series was reviewed, including reports, published in English, containing adult patient descriptions. Duplicate manuscripts were removed using EndNote. The following case-level data were collected from the manuscripts: age, gender, patient country or region of origin, author country/continent of residence, skin cancer-related, and other key dermatologic features. 381 published articles, with a total of 578 SOC patients, met criteria for inclusion. SOC patients can present with fewer classic findings, such as a lower incidence of basal cell carcinomas (44%) in SOC Gorlin syndrome patients than palmar pits (66%) and mandibular cysts (66%). Differences between SOC populations were also noted, such as leukoplakia being more common in Asian dyskeratosis congenita patients (80%) in comparison to African dyskeratosis congenita patients (44%). SOC patients also have varying onset of skin cancer depending on the genodermatosis, from a median of 25 years of age in Rothmund-Thomson syndrome to 53 in Muir-Torre syndrome. In this review, SOC patients with genodermatoses can have varying presentations. Being cognizant of these characteristics may lead to earlier diagnosis and interventions to mitigate skin-cancer-related morbidity in SOC patients.

Anandamide is an Early Blood Biomarker of Hermansky-Pudlak Syndrome Pulmonary Fibrosis

Hermansky-Pudlak syndrome (HPS) is a group of rare genetic disorders, with several subtypes leading to fatal adult-onset pulmonary fibrosis (PF) and no effective treatment. Circulating biomarkers detecting early PF have not been identified. We investigated whether endocannabinoids could serve as blood biomarkers of PF in HPS. We measured endocannabinoids in the serum of HPS, IPF, and healthy human subjects and in a mouse model of HPSPF. Pulmonary function tests (PFT) were correlated with endocannabinoid measurements. In a pale ear mouse model of bleomycin-induced HPSPF, serum endocannabinoid levels were measured with and without treatment with zevaquenabant (MRI-1867), a peripheral CB1R and iNOS antagonist. In three separate cohorts, circulating anandamide levels were increased in HPS-1 patients with or without PF, compared to healthy volunteers. This increase was not observed in IPF patients or in HPS-3 patients, who do not have PF. Circulating anandamide (AEA) levels were negatively correlated with PFT. Furthermore, a longitudinal study over the course of 5-14 years with HPS-1 patients indicated that circulating AEA levels begin to increase with the fibrotic lung process even at the subclinical stages of HPSPF. In pale ear mice with bleomycin-induced HpsPF, serum AEA levels were significantly increased in the earliest stages of PF and remained elevated at a later fibrotic stage. Zevaquenabant treatment reduced the increased AEA levels and attenuated progression in bleomycin-induced HpsPF. Circulating AEA may be a prognostic blood biomarker for PF in HPS-1 patients. Further studies are indicated to evaluate endocannabinoids as potential surrogate biomarkers in progressive fibrotic lung diseases.

Lung repair and regeneration: Advanced models and insights into human disease

The respiratory system acts as both the primary site of gas exchange and an important sensor and barrier to the external environment. The increase in incidences of respiratory disease over the past decades has highlighted the importance of developing improved therapeutic approaches. This review will summarize recent research on the cellular complexity of the mammalian respiratory system with a focus on gas exchange and immunological defense functions of the lung. Different models of repair and regeneration will be discussed to help interpret human and animal data and spur the investigation of models and assays for future drug development.

Long-term nintedanib treatment for progressive pulmonary fibrosis associated with Hermansky-Pudlak syndrome type 1 followed by lung transplantation

Hermansky-Pudlak syndrome (HPS) is a rare autosomal recessive disease that often causes progressive pulmonary fibrosis (HPS-PPF) in some genetic types with high mortality rates. No effective treatment for HPS-PPF other than lung transplantation has been established. Herein, we report a case of HPS type 1 with progressive pulmonary fibrosis treated with long-term nintedanib administration followed by lung transplantation. The resected lungs revealed diffuse interstitial lung lesions, including fibroblastic foci, suggesting the potential beneficial effects of anti-fibrotic drugs in HPS-PPF. Together with previous reports, the present case suggests that nintedanib might be a safe and effective drug for HPS-PPF.

Hermansky-Pudlak syndrome with early onset inflammatory bowel disease due to loss of dysbindin expression

Hermansky-Pudlak syndrome (HPS) is a heterogeneous group of autosomal recessive genetic disorders characterized by oculocutaneous albinism, bleeding diathesis, and variable presentation of immune deficiency and dysregulation. The pathogenesis of HPS involves mutations in genes responsible for biogenesis and trafficking of lysosome-related organelles, essential for the function of melanosomes, platelet granules, and immune cell granules. Eleven genes coding for proteins in the BLOC-1, BLOC-2, BLOC-3 and AP-3 complexes have been implicated in the pathogenesis of HPS. To date, the rare subtype HPS-7 associated with bi-allelic mutations in DTNBP1 (dysbindin) has only been reported in 9 patients. We report a novel DTNBP1 splicing mutation in a 15-month-old patient with HPS-7 phenotype and severe inflammatory bowel disease (IBD). This patient's leukocytes have undetectable dysbindin protein. We also identify dysregulated expression of several genes involved in activation of the adaptive immune response. This case underscores the emerging immunological consequences of dysbindin deficiency and suggests that DTNBP1 mutations may underlie some rare cases of very early onset IBD.

A case of Hermansky-Pudlak with dyspnea

Hermansky-Pudlak syndrome (HPS) is a rare multisystem disorder inherited in an autosomal recessive manner. Its prevalence is 1 in 500 000 to 1 000 000 people worldwide. The cause of this disorder is genetic mutations that lead to defective organelles of lysosomes. In this report, a 49-year-old man is introduced who was referred to the medical center with ocular albinism and recently exacerbated shortness of breath. Imaging showed peripheral reticular opacities, ground-glass opacities of the lungs with subpleural sparing in some regions, and thickening of bronchovascular bundles, which were all in favor of non-specific interstitial pneumonia. This imaging pattern is an unusual finding in a patient with HPS.

Oculocutaneous albinism and bleeding diathesis due to a novel deletion in the HPS3 gene

Hermansky–Pudlak syndrome (HPS) is a group of rare autosomal recessive disorders characterized by oculocutaneous albinism (OCA) and bleeding diathesis. To date, 11 HPS types have been reported (HPS-1 to HPS-11), each defined by disease-causing variants in specific genes. Variants in the HPS1 gene were found in approximately 15% of HPS patients, most of whom harbor the Puerto Rican founder mutation. In this study, we report six affected individuals from three nonconsanguineous families of Ashkenazi Jewish descent, who presented with OCA and multiple ecchymoses and had normal platelet number and size. Linkage analysis indicated complete segregation to HPS3. Sequencing of the whole coding region and the intron boundaries of HPS3 revealed a heterozygous c.1163+1G>A variant in all six patients. Long-range PCR amplification revealed that all affected individuals also carry a 14,761bp deletion that includes the 5′UTR and exon 1 of HPS3, encompassing regions with long interspersed nuclear elements. The frequency of the c.1163+1G>A splice site variant was found to be 1:200 in the Ashkenazi Jewish population, whereas the large deletion was not detected in 300 Ashkenazi Jewish controls. These results present a novel HPS3 deletion mutation and suggest that the prevalence of HPS-3 in Ashkenazi Jews is more common than previously thought.

NGS-based targeted sequencing identified two novel variants in Southwestern Chinese families with oculocutaneous albinism

BACKGROUND

Oculocutaneous albinism (OCA) is a group of heterogeneous genetic diseases characterized by a reduction or complete lack of pigmentation in the hair, skin, and eyes. It is associated with reduced visual acuity, nystagmus, photophobia, and strabismus. OCA type 1 (OCA1) and type 2 (OCA2) are caused by mutations in the tyrosinase (TYR) and OCA2 genes, which are responsible for most cases of OCA. The present study aimed to identify the mutational spectra of 18 southwest Chinese probands with OCA.

RESULTS

We used a skin disease-targeted panel to sequence more than 400 genes, including 23 genes (TYR, OCA2, AP3B1, BLOC1S3, BLOC1S6, C10orf11, DTNBP1, FRMD7, GPR143, HPS1, HPS3, HPS4, HPS5, HPS6, LYST, MC1R, MITF, MLPH, MYO5A, RAB27A, SLC24A5, SLC45A2, TYRP1) associated with syndromic and non-syndromic albinism. The targeted panel was applied to 18 patients from southwest China, nine (50%) patients were diagnosed with OCA1, and nine (50%) were diagnosed with OCA2. Our data indicate that OCA1 and OCA2, the most common subtypes, probably have the same prevalence in southwest China. In total, we identified 26 variants in TYR and OCA2 from 18 OCA cases using the NGS technology, including 24 variants presented in the Human Gene Mutation Database Professional (HGMD) and two novel variants, c.559_560insCATTATTATGTGTCAAATTATCCCC in TYR and c.1514 T > C in OCA2, which have not been previously reported. According to the American College of Medical Genetics and Genomics (ACMG) classification, c.559_560insCATTATTATGTGTCAAATTATCCCC (p.G190Cfs*12) is classified as a pathogenic variant, and c.1514 T > C (p.F505S) is evaluated as a likely pathogenic variant.

CONCLUSIONS

Two novel variants were identified which will expand the mutational spectra of TYR and OCA2. The results of the present study may have implications for genetic counseling, carrier screening, and clinical management of the disease.

Zebrafish Syndromic Albinism Models as Tools for Understanding and Treating Pigment Cell Disease in Humans

Simple Summary

Zebrafish (Danio rerio) is an emerging model for studying many diseases, including disorders originating in black pigment cells, melanocytes. In this review of the melanocyte literature, we discuss the current knowledge of melanocyte biology relevant to understanding different forms of albinism and the potential of the zebrafish model system for finding novel mechanisms and treatments.

Abstract

Melanin is the pigment that protects DNA from ultraviolet (UV) damage by absorbing excess energy. Melanin is produced in a process called melanogenesis. When melanogenesis is altered, diseases such as albinism result. Albinism can result in an increased skin cancer risk. Conversely, black pigment cell (melanocyte) development pathways can be misregulated, causing excessive melanocyte growth that leads to melanoma (cancer of melanocytes). Zebrafish is an emerging model organism used to study pigment disorders due to their high fecundity, visible melanin development in melanophores (melanocytes in mammals) from 24 h post-fertilization, and conserved melanogenesis pathways. Here, we reviewed the conserved developmental pathways in zebrafish melanophores and mammalian melanocytes. Additionally, we summarized the progress made in understanding pigment cell disease and evidence supporting the strong potential for using zebrafish to find novel treatment options for albinism.

Hermansky-Pudlak syndrome type 2: A rare cause of severe periodontitis in adolescents-A case study

BACKGROUND AND AIMS

Hermansky-Pudlak syndrome (HPS) is an autosomal recessive disorder characterized by oculocutaneous albinism (OCA) and platelet storage pool deficiency. The HPS-2 subtype is distinguished by neutropenia, and little is known about its periodontal phenotype in adolescents. AP3B1 is the causative gene for HPS-2. A 13-year-old Chinese girl presented to our department suffering from gingival bleeding and tooth mobility. Her dental history was otherwise unremarkable. Suspecting some systemic diseases as the underlying cause, the patient was referred for medical consultation, a series of blood tests, and genetic tests. In this case study, periodontal status and mutation screening of one HPS-2 case are presented.

METHODS

Blood analysis including a complete blood count (CBC) and glycated hemoglobin levels were measured. Platelet transmission electron microscopy (PTEM) was performed to observe the dense granules in platelets. Whole-exome sequencing (WES) and Sanger sequencing were performed to confirm the pathogenic variants.

RESULTS

A medical diagnosis of HPS-2 was assigned to the patient. Following the medical diagnosis, a periodontal diagnosis of "periodontitis as a manifestation of systemic disease" was assigned to the patient. We identified novel compound heterozygous variants in AP3B1 (NM_003664.4: exon7: c.763C>T: p.Q255^*) and (NM_003664.4: exon1: c.53_56dup: p.E19Dfs^*21) in this Chinese pedigree with HPS-2.

CONCLUSION

This case study indicates the importance of periodontitis as a possible indicator of underlying systemic disease. Systemic disease screening is needed when a young patient presents with unusual, severe periodontitis, as the oral condition may be the first of a systemic abnormality. Our work also expands the spectrum of AP3B1 mutations and further provides additional genetic testing information for other HPS-2 patients.

Vtc5 Is Localized to the Vacuole Membrane by the Conserved AP-3 Complex to Regulate Polyphosphate Synthesis in Budding Yeast

Polyphosphates (polyP) are energy-rich polymers of inorganic phosphates assembled into chains ranging from 3 residues to thousands of residues in length. They are thought to exist in all cells on earth and play roles in an eclectic mix of functions ranging from phosphate homeostasis to cell signaling, infection control, and blood clotting. In the budding yeast Saccharomyces cerevisiae, polyP chains are synthesized by the vacuole-bound vacuolar transporter chaperone (VTC) complex, which synthesizes polyP while simultaneously translocating it into the vacuole lumen, where it is stored at high concentrations. VTC’s activity is promoted by an accessory subunit called Vtc5. In this work, we found that the conserved AP-3 complex is required for proper Vtc5 localization to the vacuole membrane. In human cells, previous work has demonstrated that mutation of AP-3 subunits gives rise to Hermansky-Pudlak syndrome, a rare disease with molecular phenotypes that include decreased polyP accumulation in platelet dense granules. In yeast AP-3 mutants, we found that Vtc5 is rerouted to the vacuole lumen by the endosomal sorting complex required for transport (ESCRT), where it is degraded by the vacuolar protease Pep4. Cells lacking functional AP-3 have decreased levels of polyP, demonstrating that membrane localization of Vtc5 is required for its VTC stimulatory activity in vivo. Our work provides insight into the molecular trafficking of a critical regulator of polyP metabolism in yeast. We speculate that AP-3 may also be responsible for the delivery of polyP regulatory proteins to platelet dense granules in higher eukaryotes.

Inherited Platelet Disorders

Bleeding disorders due to platelet dysfunction are a common hematologic complication affecting patients, and typically present with mucocutaneous bleeding or hemorrhage. An inherited platelet disorder should be suspected in individuals with a suggestive family history and no identified secondary causes of bleeding. Genetic defects have been described at all levels of platelet activation, including receptor binding, signaling, granule release, cytoskeletal remodeling, and platelet hematopoiesis. Management of these disorders is typically supportive, with an emphasis on awareness, patient education, and anticipatory guidance to prevent future episodes of bleeding.

Clinical phenocopies of albinism

PURPOSE

To present a series of patients diagnosed with oculocutaneous albinism (OCA) based on clinical presentation who were later proven to have a different diagnosis.

METHODS

The medical records of patients seen at the Pediatric Inherited Eye Disease Clinic of the University of Iowa from 1980 to 2018 who were eventually discovered to have an incorrect diagnosis of OCA were reviewed retrospectively.

RESULTS

Eight pediatric patients presenting with clinical features suggestive of OCA which changed to a different diagnosis over time were identified. Presenting clinical features included fair pigmentation of the skin and adnexa (8/8), congenital nystagmus (6/8), decreased visual acuity (8/8), iris transillumination defects (8/8), and foveal hypoplasia (7/8). Of the 8 patients, 4 manifested progressive, preschool-age-onset myopia. Other associated clinical features included hearing loss (3), seizures (1), abnormal chest x-ray (1) and easy bruising (2). During follow-up, additional clinical features and genetic testing proved that they have different clinical entities, namely, Knobloch syndrome, Jeune syndrome, Donnai-Barrow syndrome, Waardenburg syndrome, Aniridia syndrome, Stickler syndrome, and Hermansky-Pudlak syndrome, one of the syndromic types of OCA.

CONCLUSIONS

Clinical features used to diagnose OCA also occur in other disorders. For a definitive diagnosis of OCA, ancillary/genetic testing must be performed. Clinical features not typically found in association with albinism, such as hearing loss, or early onset, or progressive myopia, may indicate the need for more extensive investigation.

Effects of Cocoa Genotypes on Coat Color, Platelets and Coagulation Parameters in French Bulldogs

A nonsense variant in HPS3, c.2420G>A or p.Trp807*, was recently discovered as the cause for a brown coat color termed cocoa in French Bulldogs. Here, we studied the genotype-phenotype correlation regarding coat color in HPS3 mutant dogs that carried various combinations of mutant alleles at other coat color genes. Different combinations of HPS3, MLPH and TYRP1 genotypes resulted in subtly different shades of brown coat colors. As HPS3 variants in humans cause the Hermansky-Pudlak syndrome type 3, which in addition to oculocutaneous albinism is characterized by a storage pool deficiency leading to bleeding tendency, we also investigated the phenotypic consequences of the HPS3 variant in French Bulldogs on hematological parameters. HPS3 mutant dogs had a significantly lowered platelet dense granules abundance. However, no increased bleeding tendencies in daily routine were reported by dog owners. We therefore conclude that in dogs, the phenotypic effect of the HPS3 variant is largely restricted to pigmentation. While an effect on platelet morphology is evident, we did not obtain any indications for major health problems associated with the cocoa coat color in French Bulldogs. Further studies will be necessary to definitely rule out very subtle effects on visual acuity or a clinically relevant bleeding disorder.

CB1 R and iNOS are distinct players promoting pulmonary fibrosis in Hermansky-Pudlak syndrome

Hermansky-Pudlak syndrome (HPS) is a rare genetic disorder which, in its most common and severe form, HPS-1, leads to fatal adult-onset pulmonary fibrosis (PF) with no effective treatment. We evaluated the role of the endocannabinoid/CB1 R system and inducible nitric oxide synthase (iNOS) for dual-target therapeutic strategy using human bronchoalveolar lavage fluid (BALF), lung samples from patients with HPS and controls, HPS-PF patient-derived lung fibroblasts, and bleomycin-induced PF in pale ear mice (HPS1ep/ep ). We found overexpression of CB1 R and iNOS in fibrotic lungs of HPSPF patients and bleomycin-infused pale ear mice. The endocannabinoid anandamide was elevated in BALF and negatively correlated with pulmonary function parameters in HPSPF patients and pale ear mice with bleomycin-induced PF. Simultaneous targeting of CB1 R and iNOS by MRI-1867 yielded greater antifibrotic efficacy than inhibiting either target alone by attenuating critical pathologic pathways. Moreover, MRI-1867 treatment abrogated bleomycin-induced increases in lung levels of the profibrotic interleukin-11 via iNOS inhibition and reversed mitochondrial dysfunction via CB1 R inhibition. Dual inhibition of CB1 R and iNOS is an effective antifibrotic strategy for HPSPF.

Automated Digital Quantification of Pulmonary Fibrosis in Human Histopathology Specimens

Pulmonary fibrosis is characterized by abnormal interstitial extracellular matrix and cellular accumulations. Methods quantifying fibrosis severity in lung histopathology samples are semi-quantitative, subjective, and analyze only portions of sections. We sought to determine whether automated computerized imaging analysis shown to continuously measure fibrosis in mice could also be applied in human samples. A pilot study was conducted to analyze a small number of specimens from patients with Hermansky-Pudlak syndrome pulmonary fibrosis (HPSPF) or idiopathic pulmonary fibrosis (IPF). Digital images of entire lung histological serial sections stained with picrosirius red and alcian blue or anti-CD68 antibody were analyzed using dedicated software to automatically quantify fibrosis, collagen, and macrophage content. Automated fibrosis quantification based on parenchymal tissue density and fibrosis score measurements was compared to pulmonary function values or Ashcroft score. Automated fibrosis quantification of HPSPF lung explants was significantly higher than that of IPF lung explants or biopsies and was also significantly higher in IPF lung explants than in IPF biopsies. A high correlation coefficient was found between some automated quantification measurements and lung function values for the three sample groups. Automated quantification of collagen content in lung sections used for digital image analyses was similar in the three groups. CD68 immunolabeled cell measurements were significantly higher in HPSPF explants than in IPF biopsies. In conclusion, computerized image analysis provides access to accurate, reader-independent pulmonary fibrosis quantification in human histopathology samples. Fibrosis, collagen content, and immunostained cells can be automatically and individually quantified from serial sections. Robust automated digital image analysis of human lung samples enhances the available tools to quantify and study fibrotic lung disease.

A family history of Hermansky-Pudlak syndrome complicated with pulmonary fibrosis: a case series and review

The Hernansky-Pudlak syndrome (HPS) is a rare genetic disorder. We report three cases from a family of 12 siblings, with six albinos, of whom four and the father had pulmonary fibrosis (PF). Case 1 was admitted to our hospital due to increasing dyspnoea and history of gynaecological bleeding. Pulmonary function test showed a restrictive airflow pattern, high-resolution computed tomographic scan demonstrated interstitial lung disease (ILD), and platelet aggregation was compromised with a reduced number of platelet dense bodies. The family history revealed endogamy and 11 members with suspected HPS. One of the albino sisters and the father had passed away with unidentified ILD, an albino brother died 14 years earlier, his autopsy had shown collections of ceroid pigments in the lungs, consistent with HPS, and another brother was followed up at our hospital for ILD and compromised platelet aggregation. This family probably has the highest number of members affected by HPS in Spain.

Hermansky-Pudlak Syndrome and Lung Disease: Pathogenesis and Therapeutics

Hermansky-Pudlak Syndrome (HPS) is a rare, genetic, multisystem disorder characterized by oculocutaneous albinism (OCA), bleeding diathesis, immunodeficiency, granulomatous colitis, and pulmonary fibrosis. HPS pulmonary fibrosis (HPS-PF) occurs in 100% of patients with subtype HPS-1 and has a similar presentation to idiopathic pulmonary fibrosis. Upon onset, individuals with HPS-PF have approximately 3 years before experiencing signs of respiratory failure and eventual death. This review aims to summarize current research on HPS along with its associated pulmonary fibrosis and its implications for the development of novel treatments. We will discuss the genetic basis of the disease, its epidemiology, and current therapeutic and clinical management strategies. We continue to review the cellular processes leading to the development of HPS-PF in alveolar epithelial cells, lymphocytes, mast cells, and fibrocytes, along with the molecular mechanisms that contribute to its pathogenesis and may be targeted in the treatment of HPS-PF. Finally, we will discuss emerging new cellular and molecular approaches for studying HPS, including lentiviral-mediated gene transfer, induced pluripotent stem cells (iPSCs), organoid and 3D-modelling, and CRISPR/Cas9-based gene editing approaches.

Hermansky-Pudlak Syndrome: A Rare Cause of Post-polypectomy Bleeding

A colonoscopy is an effective tool for colorectal cancer screening, which aims at identifying precancerous polyps and removing them. Post-polypectomy bleeding (PPB) is one of the most common complications of endoscopic polypectomy. Here, we report a rare and interesting case of a 68-year-old man known to have Hermansky-Pudlak syndrome (HPS) who presented with two days history of rectal bleeding one day after he had a screening colonoscopy with polypectomy. He had a drop in his hemoglobin count and was admitted to the medicine floor and given 1-desamino-8-D-arginine vasopressin (DDAVP). Later, his bleeding stopped and he reported improvement in his symptoms. This case illustrates the importance of considering platelet transfusion and/or administration during minor surgical procedures for patients with bleeding diathesis such as Hermansky-Pudlak syndrome.

A genome-wide copper-sensitized screen identifies novel regulators of mitochondrial cytochrome c oxidase activity

Copper is essential for the activity and stability of cytochrome c oxidase (CcO), the terminal enzyme of the mitochondrial respiratory chain. Loss-of-function mutations in genes required for copper transport to CcO result in fatal human disorders. Despite the fundamental importance of copper in mitochondrial and organismal physiology, systematic identification of genes that regulate mitochondrial copper homeostasis is lacking. To discover these genes, we performed a genome-wide screen using a library of DNA-barcoded yeast deletion mutants grown in copper-supplemented media. Our screen recovered a number of genes known to be involved in cellular copper homeostasis as well as genes previously not linked to mitochondrial copper biology. These newly identified genes include the subunits of the adaptor protein 3 complex (AP-3) and components of the cellular pH-sensing pathway Rim20 and Rim21, both of which are known to affect vacuolar function. We find that AP-3 and Rim mutants exhibit decreased vacuolar acidity, which in turn perturbs mitochondrial copper homeostasis and CcO function. CcO activity of these mutants could be rescued by either restoring vacuolar pH or supplementing growth media with additional copper. Consistent with these genetic data, pharmacological inhibition of the vacuolar proton pump leads to decreased mitochondrial copper content and a concomitant decrease in CcO abundance and activity. Taken together, our study uncovered novel genetic regulators of mitochondrial copper homeostasis and provided a mechanism by which vacuolar pH impacts mitochondrial respiration through copper homeostasis.

Interstitial Pneumonia Secondary to Hermansky-Pudlak Syndrome Type 4 Treated with Different Antifibrotic Agents

Hermansky-Pudlak syndrome (HPS) is an autosomal recessive hereditary disease that may be complicated by progressive and potentially fatal interstitial pneumonia. We herein report a 64-year-old woman with interstitial pneumonia associated with HPS type 4 whom we treated with nintedanib after pirfenidone proved ineffective. To our knowledge, there have been no previous reports of nintedanib being used to treat a patient with HPS type 4. There is a need for clinical trials of antifibrotic agents, including nintedanib, pirfenidone, and new therapeutic agents with different mechanisms of action in these patients.

Hermansky-Pudlak syndrome pulmonary fibrosis: a rare inherited interstitial lung disease

Pulmonary fibrosis is a progressive interstitial lung disease of unknown aetiology with a poor prognosis. Studying genetic diseases associated with pulmonary fibrosis provides insights into the pathogenesis of the disease. Hermansky-Pudlak syndrome (HPS), a rare autosomal recessive disorder characterised by abnormal biogenesis of lysosome-related organelles, manifests with oculocutaneous albinism and excessive bleeding of variable severity. Pulmonary fibrosis is highly prevalent in three out of 10 genetic types of HPS (HPS-1, HPS-2 and HPS-4). Thus, genotyping of individuals with HPS is clinically relevant. HPS-1 tends to affect Puerto Rican individuals due to a genetic founder effect. HPS pulmonary fibrosis shares some clinical features with idiopathic pulmonary fibrosis (IPF), including dyspnoea, cough, restrictive lung physiology and computed tomography (CT) findings of fibrosis. In contrast to IPF, HPS pulmonary fibrosis generally affects children (HPS-2) or middle-aged adults (HPS-1 or HPS-4) and may be associated with ground-glass opacification in CT scans. Histopathology of HPS pulmonary fibrosis, and not IPF, shows vacuolated hyperplastic type II cells with enlarged lamellar bodies and alveolar macrophages with lipofuscin-like deposits. Antifibrotic drugs approved as treatment for IPF are not approved for HPS pulmonary fibrosis. However, lung transplantation has been performed in patients with severe HPS pulmonary fibrosis. HPS pulmonary fibrosis serves as a model for studying fibrotic lung disease and fibrosis in general.

Hermansky-Pudlak syndrome-2 alters mitochondrial homeostasis in the alveolar epithelium of the lung

BACKGROUND

Mitochondrial dysfunction has emerged as an important player in the pathogenesis of idiopathic pulmonary fibrosis (IPF), a common cause of idiopathic interstitial lung disease in adults. Hermansky-Pudlak syndrome (HPS) is a rare autosomal recessive disorder that causes a similar type of pulmonary fibrosis in younger adults, although the role of mitochondrial dysfunction in this condition is not understood.

METHODS

We performed a detailed characterization of mitochondrial structure and function in lung tissues and alveolar epithelial cells deficient in the adaptor protein complex 3 beta 1 (Ap3b1) subunit, the gene responsible for causing subtype 2 of HPS (HPS-2).

RESULTS

We observed widespread changes in mitochondrial homeostasis in HPS-2 cells, including the acquisition of abnormally shaped mitochondria, with reduced number of cristae, and markedly reduced activity of the electron transport chain and the tricarboxylic acid cycle. We also found that mitochondrial redox imbalance and activity of the mitochondrial unfolded protein response were dysregulated in HPS-2 cells and this associated with various other changes that appeared to be compensatory to mitochondrial dysfunction. This included an increase in glycolytic activity, an upregulation in the expression of mitochondrial biogenesis factors and enhanced activation of the energy-conserving enzyme AMP-activated protein kinase.

CONCLUSION

In summary, our findings indicate that mitochondrial function is dramatically altered in HPS-2 lung tissues, suggesting dysfunction of this organelle might be a driver of HPS lung disease.

Higher Incidence of B Cell Malignancies in Primary Immunodeficiencies: A Combination of Intrinsic Genomic Instability and Exocytosis Defects at the Immunological Synapse

Congenital defects of the immune system called primary immunodeficiency disorders (PID) describe a group of diseases characterized by a decrease, an absence, or a malfunction of at least one part of the immune system. As a result, PID patients are more prone to develop life-threatening complications, including cancer. PID currently include over 400 different disorders, however, the variety of PID-related cancers is narrow. We discuss here reasons for this clinical phenotype. Namely, PID can lead to cell intrinsic failure to control cell transformation, failure to activate tumor surveillance by cytotoxic cells or both. As the most frequent tumors seen among PID patients stem from faulty lymphocyte development leading to leukemia and lymphoma, we focus on the extensive genomic alterations needed to create the vast diversity of B and T lymphocytes with potential to recognize any pathogen and why defects in these processes lead to malignancies in the immunodeficient environment of PID patients. In the second part of the review, we discuss PID affecting tumor surveillance and especially membrane trafficking defects caused by altered exocytosis and regulation of the actin cytoskeleton. As an impairment of these membrane trafficking pathways often results in dysfunctional effector immune cells, tumor cell immune evasion is elevated in PID. By considering new anti-cancer treatment concepts, such as transfer of genetically engineered immune cells, restoration of anti-tumor immunity in PID patients could be an approach to complement standard therapies.

Hermansky-Pudlak syndrome-associated pneumothorax with rapid progression of respiratory failure: a case report

Background

Hermansky-Pudlak syndrome (HPS) is an extremely rare disease with pulmonary fibrosis (PF), oculocutaneous albinism, induced platelet dysfunction, and granulomatous colitis. Although patients with HPS-associated PF (HPS-PF) often receive treatment with anti-fibrotic agents, including pirfenidone, many HPS-PF cases are progressive. The development of pneumothorax is known to be rare in HPS-PF. Pneumothorax development is generally important for prognosis in patients with interstitial pneumonia. However, there are few reports regarding the development of pneumothorax in patients with HPS-PF.

Case presentation

A 50-year-old Japanese man with chestnut hair, white skin, and light brown squint eyes visited our hospital for interstitial pneumonia examination. Chest high-resolution computed tomography (HRCT) demonstrated diffuse bilateral reticular opacities along the bronchovascular bundles and traction bronchiectasis predominantly in the upper lung fields. He was definitively diagnosed with HPS because genetic analysis showed that he had a homozygous mutation, c.398 + 5G > A, in the HPS-1 gene. After diagnosis with HPS-PF, he initiated home oxygen therapy due to gradually progressive hypoxemia.

Three months after the HPS-PF diagnosis, the patient suddenly developed severe chest pain and dyspnea and was admitted to our hospital on emergency. He was diagnosed with pneumothorax by chest radiological findings. He immediately received chest drainage; however, his pneumothorax did not improve. Therefore, he underwent video-assisted surgery by thoracic surgeons. The leak point was not detected, but multiple bullae were found, mainly in the upper lung lobes. Thus, the surgeons did not perform bullectomy and only covered the apical areas. Fifteen days after the surgery, the patient developed high fever and dyspnea with a new diffuse reticular shadow found through HRCT. We first initiated the patient on broad-spectrum antibiotics; however, the symptoms and radiological findings worsened. Therefore, we started treatment with pirfenidone for inhibition of PF progression. The patient re-developed pneumothorax with severe respiratory failure. Although he re-underwent chest drainage, he died of progressive respiratory failure.

Conclusions

We herein report the case of a rare HPS patient who developed pneumothorax with progressive PF. Pneumothorax may cause rapid progressive respiratory failure and may be associated with PF progression in HPS-PF.

Combined deficiency of RAB32 and RAB38 in the mouse mimics Hermansky-Pudlak syndrome and critically impairs thrombosis

The biogenesis of lysosome related organelles is defective in Hermansky-Pudlak syndrome (HPS), a disorder characterized by oculocutaneous albinism and platelet dense granule (DG) defects. The first animal model of HPS was the fawn-hooded rat, harboring a spontaneous mutation inactivating the small guanosine triphosphatase Rab38 This leads to coat color dilution associated with the absence of DGs and lung morphological defects. Another RAB38 mutant, the cht mouse, has normal DGs, which has raised controversy about the role of RAB38 in DG biogenesis. We show here that murine and human, but not rat, platelets also express the closely related RAB32. To elucidate the parts played by RAB32 and RAB38 in the biogenesis of DGs in vivo and their effects on platelet functions, we generated mice inactivated for Rab32, Rab38, and both genes. Single Rab38 inactivation mimicked cht mice, whereas single Rab32 inactivation had no effect in DGs, coat color, or lung morphology. By contrast, Rab32/38 double inactivation mimicked severe HPS, with strong coat and eye pigment dilution, some enlarged lung multilamellar bodies associated with a decrease in the number of DGs. These organelles were morphologically abnormal, decreased in number, and devoid of 5-hydroxytryptamine content. In line with the storage pool defect, platelet activation was affected, resulting in severely impaired thrombus growth and prolongation of the bleeding time. Overall, our study demonstrates the absence of impact of RAB38 or RAB32 single deficiency in platelet biogenesis and function resulting from full redundancy, and characterized a new mouse model mimicking HPS devoid of DG content.

The future is here: Integrating genetics into the pediatric pulmonary clinic

Recognition of underlying genetic etiologies of disease is increasing at an exponential rate, likely due to greater access to and lower cost of genetic testing. Monogenic causes of disease, or conditions resulting from a mutation or mutations in a single gene, are now well recognized in every subspecialty, including pediatric pulmonary medicine; thus, it is important to consider genetic conditions when evaluating children with respiratory disease. In the pediatric pulmonary clinic, genetic testing should be considered when multiple family members present with similar or related clinical features and when individuals have unusual clinical presentations, such as early-onset disease or complex, syndromic features. This review provides a practical guide for genetic diagnosis in the pediatric pulmonary setting, including a review of genetic concepts, considerations for test selection and results in interpretation, as well as an overview of genetic differential diagnoses for common pediatric pulmonary phenotypes. Genetic conditions that commonly present to the pediatric pulmonary clinic are reviewed in a companion article by Yonker et al.

Recognizing genetic disease: A key aspect of pediatric pulmonary care

Advancement in technology has improved recognition of genetic etiologies of disease, which has impacted diagnosis and management of rare disease patients in the pediatric pulmonary clinic. This review provides an overview of genetic conditions that are likely to present with pulmonary features and require extensive care by the pediatric pulmonologist. Increased familiarity with these conditions allows for improved care of these patients by reducing time to diagnosis, tailoring management, and prompting further investigation into these disorders.

Platelet Disorders

After vascular injury and exposure of subendothelial matrix proteins to the intravascular space, mediators of hemostasis are triggered and allow for clot formation and restoration of vascular integrity. Platelets are the mediators of primary hemostasis, creating a platelet plug and allowing for initial cessation of bleeding. Platelet disorders, qualitative and quantitative, may result in bleeding signs and symptoms, particularly mucocutaneous bleeding such as epistaxis, bruising, petechiae, and heavy menstrual bleeding. Increasing evidence suggests that platelets have functional capabilities beyond hemostasis, but this review focuses solely on platelet hemostatic properties. Herein, normal platelet function as well as the effects of abnormal function and thrombocytopenia are reviewed.

Familial Interstitial Lung Disease

The interstitial lung diseases (ILDs) are a group of progressive disorders characterized by chronic inflammation and/or fibrosis in the lung. While some ILDs can be linked to specific environmental causes (i.e., asbestosis, silicosis), in many individuals, no culprit exposure can be identified; these patients are deemed to have "idiopathic interstitial pneumonia" (IIP). Family history is now recognized as the strongest risk factor for IIP, and IIP cases that run in families comprise a syndrome termed "familial interstitial pneumonia" (FIP). Mutations in more than 10 different genes have been implicated as responsible for disease in FIP families. Diverse ILD clinical phenotypes can be seen within a family, and available evidence suggests underlying genetic risk is the primary determinant of disease outcomes. Together, these FIP studies have provided unique insights into the pathobiology of ILDs, and brought focus on the unique issues that arise in the care of patients with FIP.

Different functions of biogenesis of lysosomal organelles complex 3 subunit 1 (Hps1) and adaptor-related protein complex 3, beta 1 subunit (Ap3b1) genes on spermatogenesis and male fertility

Hermansky-Pudlak syndrome (HPS) is an autosomal recessive disorder in humans and mice. Pale ear (ep) and pearl (pe) mice, bearing mutations in the biogenesis of lysosomal organelles complex 3 subunit 1 (Hps1) and adaptor-related protein complex 3, beta 1 subunit (Ap3b1) genes respectively, are mouse models of human HPS Type 1 (HPS1) and Type 2 (HPS2) respectively. In the present study we investigated and compared the reduced fertilities of ep and pe male mice. Both ep and pe males exhibited lower abilities to impregnate C57BL/6J (B6) females, and B6 females mated with ep males produced smaller litters than those mated with pe males. Delayed testis development, reduced sperm count and lower testosterone concentrations were observed in the pe but not ep male mice. However, the reduction in sperm motility was greater in ep than pe males, likely due to the mitochondrial and fibrous sheath abnormalities observed by electron microscopy in the sperm tails of ep males. Together, the results indicate that the Hps1 and Ap3b1 genes play distinct roles in male reproductive system development and spermatogenesis in mice, even though ep and pe males share common phenotypes, including reduced lysosomes in Sertoli cells and dislocated Zn2+ in sperm heads.

Treatment of Hermansky-Pudlak syndrome Associated granulomatous colitis with anti-TNF agents: case series and review of literature

Hermansky-Pudlak syndrome is a rare syndrome characterized by bleeding diathesis due to platelet dysfunction, oculocutaneous albinism and other systemic involvements. Granulomatous colitis may occur in the disease course and have similarities with Crohn's disease. Herein, we present four cases with Hermansky-Pudlak syndrome associated colitis with the longest follow-up period having various responses to different anti-TNF agents. Four patients with Hermansky-Pudlak syndrome colitis were started on anti-TNF agents between 2008 and 2013. After a mean follow-up period of 7.5 years, two of four patients exhibited a significant improvement in symptoms, whereas the other two experienced undesirable disease course. Although having many similarities with Crohn's disease; Hermansky-Pudlak syndrome colitis appears to have lower anti-TNF response rates. Pathophysiological differences need to be enlightened to find more appropriate therapeutic targets for Hermansky-Pudlak syndrome colitis.

The genetics of interstitial lung diseases

Interstitial lung diseases (ILDs) are a set of heterogeneous lung diseases characterised by inflammation and, in some cases, fibrosis. These lung conditions lead to dyspnoea, cough, abnormalities in gas exchange, restrictive physiology (characterised by decreased lung volumes), hypoxaemia and, if progressive, respiratory failure. In some cases, ILDs can be caused by systemic diseases or environmental exposures. The ability to treat or cure these ILDs varies based on the subtype and in many cases lung transplantation remains the only curative therapy. There is a growing body of evidence that both common and rare genetic variants contribute to the development and clinical manifestation of many of the ILDs. Here, we review the current understanding of genetic risk and ILD.

Common and rare genetic variants contribute to the development and clinical manifestation of many interstitial lung diseaseshttp://bit.ly/31loHLh