A further case of chondrodysplasia with growth failure occurring after hematopoietic stem cell transplantation (HSCT)

There is an emerging body of evidence showing that young patients, post haematopoietic stem cell transplantation (HSCT), can develop skeletal changes that mimic an osteochondrodysplasia process. The key discriminator is that these children have had otherwise normal growth and skeletal development before the therapeutic intervention (HSCT), typically for a haematological malignancy. Herein we present that case of a boy who underwent HSCT for Haemophagocytic Lymphohistiocytosis (HLH) aged 2 years. Following Intervention with HSCT this boy's growth has severely decelerated (stature less than 1st centile matched for age) and he has developed a spondyloepiphyseal dysplasia.

Phenocopy behavioral variant frontotemporal dementia: A case study

Objective: Behavioral variant frontotemporal dementia (bvFTD) is a neurodegenerative condition characterized by progressive changes in behavior, cognition, and day-to-day functioning. Progression of the disease usually leads to death 3-5 years after diagnosis. However, there are reports of individuals who are initially diagnosed with bvFTD but fail to progress. These individuals are thought to have what is becoming known as phenocopy bvFTD (phFTD). Methods: This manuscript reviews a single case study of a 68-year-old male Veteran who was diagnosed with bvFTD in 2010, which has not progressed over time. Results: Review of serial neuropsychological evaluations was broadly normal with mild evidence of executive dysfunction with minimal reliable change in his performances from 2015, 2017, and 2022 evaluations. He also has not developed neuroimaging evidence of FTD. Conclusions: This case illustrates the importance of monitoring individuals over time and incorporating neuroimaging data into the diagnosis. We believe this Veteran's presentation is most consistent with what has been described as phFTD.

X-Linked Retinoschisis Masquerading Uveitis

X-linked retinoschisis (XLRS) shows features also seen in patients with uveitis and is recognized as an uveitis masquerade syndrome. This retrospective study aimed to describe characteristics of XLRS patients with an initial uveitis diagnosis and to contrast these to patients with an initial XLRS diagnosis. Patients referred to a uveitis clinic, which turned out to have XLRS (n = 4), and patients referred to a clinic for inherited retinal diseases (n = 18) were included. All patients underwent comprehensive ophthalmic examinations, including retinal imaging with fundus photography, ultra-widefield fundus imaging, and optical coherence tomography (OCT). In patients with an initial diagnosis of uveitis, a macular cystoid schisis was always interpreted as an inflammatory macular edema; vitreous hemorrhages were commonly interpreted as intraocular inflammation. Patients with an initial diagnosis of XLRS rarely (2/18; p = 0.02) showed vitreous hemorrhages. No additional demographic, anamnestic, and anatomical differences were found. An increased awareness of XLRS as a uveitis masquerade syndrome may facilitate early diagnosis and may prevent unnecessary therapies.

Stargardt-like Clinical Characteristics and Disease Course Associated with Variants in the WDR19 Gene

Variants in WDR19 (IFT144) have been implicated as another possible cause of Stargardt disease. The purpose of this study was to compare longitudinal multimodal imaging of a WDR19-Stargardt patient, harboring p.(Ser485Ile) and a novel c.(3183+1_3184-1)_(3261+1_3262-1)del variant, with 43 ABCA4-Stargardt patients. Age at onset, visual acuity, Ishihara color vision, color fundus, fundus autofluorescence (FAF), spectral-domain optical coherence tomography (OCT) images, microperimetry and electroretinography (ERG) were evaluated. First symptom of WDR19 patient was nyctalopia at the age of 5 years. After the age of 18 years, OCT showed hyper-reflectivity at the level of the external limiting membrane/outer nuclear layer. There was abnormal cone and rod photoreceptor function on ERG. Widespread fundus flecks appeared, followed by perifoveal photoreceptor atrophy. Fovea and peripapillary retina remained preserved until the latest exam at 25 years of age. ABCA4 patients had median age of onset at 16 (range 5-60) years and mostly displayed typical Stargardt triad. A total of 19% had foveal sparing. In comparison to ABCA4 patients, the WDR19 patient had a relatively large foveal preservation and severe rod photoreceptor impairment; however, it was still within the ABCA4 disease spectrum. Addition of WDR19 in the group of genes producing phenocopies of Stargardt disease underlines the importance of genetic testing and may help to understand its pathogenesis.

Inborn Errors of Immunity and Their Phenocopies: CTLA4 and PD-1

Elucidating links between genotype and phenotype in patients with rare inborn errors of immunity (IEIs) provides insights into mechanisms of immune regulation. In many autosomal dominant IEIs, however, variation in expressivity and penetrance result in complex genotype-phenotype relations, while some autosomal recessive IEIs are so rare that it is difficult to draw firm conclusions. Phenocopies arise when an environmental or non-genetic factor replicates a phenotype conferred by a specific genotype. Phenocopies can result from therapeutic antibodies or autoantibodies that target a protein to replicate aspects of the phenotype conferred by mutations in the gene encoding the same protein. Here, we consider IEIs arising from rare genetic variants in CTLA4 and PDCD1 and compare clinical and laboratory manifestations arising as drug-induced phenocopies (immune related adverse events, IRAEs) in cancer patients treated with immune checkpoint inhibitors (ICI) and identify outstanding questions regarding mechanism of disease.

Best Vitelliform Macular Dystrophy (BVMD) is a phenocopy of North Carolina Macular Dystrophy (NCMD/MCDR1)

PURPOSE

North Carolina Macular Dystrophy (NCMD) and Best Vitelliform Macular Dystrophy (BVMD) are rare autosomal dominant macular dystrophies. Both BVMD and NCMD have markedly variable expressivity. In some individuals, it can be difficult to differentiate between the two disease entities.

METHODS

Clinical findings including fundus photography, fundus autofluorescence (FAF), and spectral domain optical coherence tomography (SD-OCT) were evaluated in 5 individuals with NCMD and 3 with BMD. Electrooculography (EOG) was performed in 2 NCMD subjects. Molecular diagnosis was performed using Sanger DNA sequencing. IRB approval was obtained.

RESULTS

Five NCMD subjects had clinical findings indistinguishable from three of our BVMD subjects. Molecular diagnosis was confirmed in all but one BVMD subject who had an abnormal EOG prior to discovery of the BEST1 gene. Two NCMD subjects had an abnormal EOG with a normal ERG, which has been considered a unique feature of BVMD. SD-OCT in one BVMD subject demonstrated a small lucency/excavation into the choroid similar to that in grade 3 lesions of NCMD. Two NCMD subjects had elevated sub-macular lesions giving a pseudo-vitelliform appearance on OCT similar to BVMD.

CONCLUSION

Best Vitelliform Macular Dystrophy can be a phenocopy of NCMD. There is considerable clinical overlap between NCMD and BVMD, which can cause diagnostic inaccuracies. Our new findings demonstrate that like BVMD, NCMD can also have an abnormal EOG with a normal ERG. The overlapping phenotypes of BVMD with NCMD may provide insights into the mechanisms of the macular changes.

Hypothyroid cardiomyopathy: A reversible phenocopy of hypertrophic cardiomyopathy

We present the case of a 46-year-old patient with hypothyroidism secondary to Hashimoto's thyroiditis who was admitted with decompensation in the form of myxedema. A 2-D echocardiogram shows a septal asymmetric hypertrophy, with low-voltage QRS complex in the ECG and a bull's-eye map of longitudinal strain with preserved apical strain with reduction of mid and basal strain that results in "cherry on the top" pattern, similar to the most frequent phenocopy of hypertrophic cardiomyopathy, as is the cardiac amyloidosis, and that, unlike this pathology, reverted after the patient reached the euthyroid state.

Brugada Pattern Phenocopy Induced by Diabetic Ketoacidosis

Brugada syndrome is a congenital cardiac channelopathy characterized by ST-segment elevation (≥2 mm) and subsequent inverted T wave in a minimum of two right precordial leads (Brugada type 1 ECG [electrocardiogram] pattern) on ECG. Brugada syndrome is estimated to be responsible for 4%-12% of all sudden cardiac deaths and up to 20% in patients with structurally normal hearts. Development of a temporary Brugada pattern, known as Brugada phenocopy, has been observed in individuals presenting with reversible underlying conditions such as hyperkalemia, hyponatremia, acidosis, ischemia, and pulmonary embolism, among others. Herein we present a case of Brugada phenocopy seen in a patient in diabetic ketoacidosis, which resolved after the electrolyte abnormalities were corrected.

Characteristics of Li-Fraumeni Syndrome in Japan; A Review Study by the Special Committee of JSHT

Li-Fraumeni syndrome (LFS) is a hereditary cancer predisposition syndrome, and the majority of patients with LFS have been identified with germline variants in the p53 tumor suppressor (TP53) gene. In the past three decades, considerable case reports of TP53 germline variants have been published in Japan. To the best of our knowledge, there have been no large-scale studies of Japanese patients with LFS. In this study, we aimed to identify Japanese patients with TP53 germline variants and to reveal the characteristics of LFS in Japan. We collected reported cases by reviewing the medical literature and cases diagnosed at the institutions of the authors. We identified 68 individuals from 48 families with TP53 germline pathogenic or likely pathogenic variants. Of the 48 families, 35 (72.9%) had missense variants, most of which were located within the DNA-binding loop. A total of 128 tumors were identified in the 68 affected individuals. The 128 tumor sites were as follows: breast, 25; bones, 16; brain, 12; hematological, 11; soft tissues, 10; stomach, 10; lung, 10; colorectum, 10; adrenal gland, 9; liver, 4; and others, 11. Unique phenotype patterns of LFS were shown in Japan in comparison to those in a large national LFS cohort study in France. Above all, a higher frequency of patients with stomach cancer was observed in Japanese TP53 germline variant carriers. These results may provide useful information for the clinical management of LFS in Japan.

Underlying pathology identified after 20 years of disease course in two cases of slowly progressive frontotemporal dementia syndromes

We report two cases from the frontotemporal lobar degeneration (FTLD) spectrum with remarkably slow progression. The first case demonstrated insidious-onset behavioral symptoms and personality changes resembling behavioral variant of frontotemporal dementia, followed a benign course over 26 years, his brain autopsy revealed the diffuse form of argyrophilic grain disease. The second case presented with slowly progressive cognitive and motor deficits, reminiscent of the corticobasal syndrome, deteriorated slowly over 22 years, his brain autopsy revealed FTLD-TDP with C9ORF72 pathology. These two cases confirm the notion of slowly progressive frontotemporal lobar degeneration caused by an underlying FTLD pathology, rather than a phenocopy.

Multiple Endocrine Neoplasia Type 1: Latest Insights

Multiple endocrine neoplasia type 1 (MEN1), a rare tumor syndrome that is inherited in an autosomal dominant pattern, is continuing to raise great interest for endocrinology, gastroenterology, surgery, radiology, genetics, and molecular biology specialists. There have been 2 major clinical practice guidance papers published in the past 2 decades, with the most recent published 8 years ago. Since then, several new insights on the basic biology and clinical features of MEN1 have appeared in the literature, and those data are discussed in this review. The genetic and molecular interactions of the MEN1-encoded protein menin with transcription factors and chromatin-modifying proteins in cell signaling pathways mediated by transforming growth factor β/bone morphogenetic protein, a few nuclear receptors, Wnt/β-catenin, and Hedgehog, and preclinical studies in mouse models have facilitated the understanding of the pathogenesis of MEN1-associated tumors and potential pharmacological interventions. The advancements in genetic diagnosis have offered a chance to recognize MEN1-related conditions in germline MEN1 mutation-negative patients. There is rapidly accumulating knowledge about clinical presentation in children, adolescents, and pregnancy that is translatable into the management of these very fragile patients. The discoveries about the genetic and molecular signatures of sporadic neuroendocrine tumors support the development of clinical trials with novel targeted therapies, along with advancements in diagnostic tools and surgical approaches. Finally, quality of life studies in patients affected by MEN1 and related conditions represent an effort necessary to develop a pharmacoeconomic interpretation of the problem. Because advances are being made both broadly and in focused areas, this timely review presents and discusses those studies collectively.

Increased insulin-like growth factor 1 concentrations in a retrospective population of non-diabetic cats diagnosed with hypertrophic cardiomyopathy

OBJECTIVES

The aim of the study was to document whether a proportion of non-diabetic cats with left ventricular hypertrophy (LVH) previously diagnosed with hypertrophic cardiomyopathy (HCM) have elevated circulating insulin-like growth factor 1 (IGF-1) concentrations.

METHODS

A retrospective analysis of residual blood samples obtained at the time of echocardiographic diagnosis of HCM from a population of 60 non-diabetic cats were analysed for circulating IGF-1 concentrations using a validated radioimmunoassay and compared with a control group of 16 apparently healthy cats without LVH. Clinical and echocardiographic data for cats with an IGF-1 level >1000 ng/ml were compared with those with an IGF-1 level <800 ng/ml.

RESULTS

In total, 6.7% (95% confidence interval 1.8-16.2%) of cats with HCM had an IGF-1 level >1000 ng/ml. The prevalence of an IGF-1 level >1000 ng/ml in the control group was zero.

CONCLUSIONS AND RELEVANCE

A small proportion of non-diabetic cats previously diagnosed with HCM had an IGF-1 concentration at a level that has been associated with feline hypersomatotropism (fHS) in the diabetic cat population. Further prospective research is required to confirm or refute the presence of fHS in non-diabetic cats with LVH and increased IGF-1.

Chondrodysplasia and growth failure in children after early hematopoietic stem cell transplantation for non-oncologic disorders

Bone dysplasias (osteochondrodysplasias) are a large group of conditions associated with short stature, skeletal disproportion, and radiographic abnormalities of skeletal elements. Nearly all are genetic in origin. We report a series of seven children with similar findings of chondrodysplasia and growth failure following early hematopoietic stem cell transplantation (HSCT) for pediatric non-oncologic disease: hemophagocytic lymphohistiocytosis or HLH (five children, three with biallelic HLH-associated variants [in PRF1 and UNC13D] and one with HLH secondary to visceral Leishmaniasis), one child with severe combined immunodeficiency and one with Omenn syndrome (both children had biallelic RAG1 pathogenic variants). All children had normal growth and no sign of chondrodysplasia at birth and prior to their primary disease. After HSCT, all children developed growth failure, with standard deviation scores for height at or below -3. Radiographically, all children had changes in the spine, metaphyses and epiphyses, compatible with a spondyloepimetaphyseal dysplasia. Genomic sequencing failed to detect pathogenic variants in genes associated with osteochondrodysplasias. We propose that such chondrodysplasia with growth failure is a novel, rare, but clinically important complication following early HSCT for non-oncologic pediatric diseases. The pathogenesis is unknown but could possibly involve loss or perturbation of the cartilage-bone stem cell population.

Intricacies of aetiology in intrafamilial degenerative disease

The genetic underpinnings of late-onset degenerative disease have typically been determined by screening families for the segregation of genetic variants with the disease trait in affected, but not unaffected, individuals. However, instances of intrafamilial etiological heterogeneity, where pathogenic variants in a culprit gene are not shared among all affected family members, continue to emerge and confound gene-discovery and genetic counselling efforts. Discordant intrafamilial cases lacking a mutation shared by other affected family members are described as disease phenocopies. This description often results in an over-simplified acceptance of an environmental cause of disease in the phenocopy cases, while the role of intrafamilial genetic heterogeneity, shared de novo mutations or epigenetic aberrations in such families is often ignored. On a related note, it is now evident that the same disease-associated variant can be present in individuals exhibiting clinically distinct phenotypes, thereby genetically uniting seemingly unrelated syndromes to form a spectrum of disease. Herein, we discuss the intricacies of determining complex degenerative disease aetiology and suggest alternative mechanisms of disease transmission that may account for the apparent missing heritability of disease.

Exome Sequencing and Identification of Phenocopies in Patients With Clinically Presumed Hereditary Nephropathies

RATIONALE & OBJECTIVE

Hereditary nephropathies are clinically and genetically heterogeneous disorders. For some patients, the clinical phenotype corresponds to a specific hereditary disease but genetic testing reveals that the expected genotype is not present (phenocopy). The aim of this study was to evaluate the spectrum and frequency of phenocopies identified by using exome sequencing in a cohort of patients who were clinically suspected to have hereditary kidney disorders.

STUDY DESIGN

Cross-sectional cohort study.

SETTING & PARTICIPANTS

174 unrelated patients were recruited for exome sequencing and categorized into 7 disease groups according to their clinical presentation. They included autosomal dominant tubulointerstitial kidney disease, Alport syndrome, congenital anomalies of the kidney and urinary tract, ciliopathy, focal segmental glomerulosclerosis/steroid-resistant nephrotic syndrome, VACTERL association, and "other."

RESULTS

A genetic diagnosis (either likely pathogenic or pathogenic variant according to the guidelines of the American College of Medical Genetics) was established using exome sequencing in 52 of 174 (30%) cases. A phenocopy was identified for 10 of the 52 exome sequencing-solved cases (19%), representing 6% of the total cohort. The most frequent phenocopies (n=5) were associated with genetic Alport syndrome presenting clinically as focal segmental glomerulosclerosis/steroid-resistant nephrotic syndrome. Strictly targeted gene panels (<25 kilobases) did not identify any of the phenocopy cases.

LIMITATIONS

The spectrum of described phenocopies is small. Selection bias may have altered the diagnostic yield within disease groups in our study population. The study cohort was predominantly of non-Finnish European descent, limiting generalizability. Certain hereditary kidney diseases cannot be diagnosed by using exome sequencing (eg, MUC1-autosomal dominant tubulointerstitial kidney disease).

CONCLUSIONS

Phenocopies led to the recategorization of disease and altered clinical management. This study highlights that exome sequencing can detect otherwise occult genetic heterogeneity of kidney diseases.

Wolff-Parkinson-White, Brugada phenocopy, and flecainide toxicity: All in one patient

Accessory pathway Wolff-Parkinson-white is sometimes not manifested till later in life, as the conduction properties of AV node become slower, other mechanisms are also possible. Brugada pattern on EKG can be associated with various underlying clinical conditions, such as mechanical compression of RVOT by tumors. It is essential to have high index of suspicion for flecainide toxicity when encountering arrhythmias in patients taking the drug.

Genetics of Nephrotic Syndrome Presenting in Childhood: Core Curriculum 2019

Nephrotic syndrome (NS) is one of the most challenging conditions to manage and treat, partly because we lack a specific molecular understanding of its pathogenesis and progression. This limits our ability to provide targeted therapy or precise prognostications. Fortunately, genomic discovery in NS and its translation to genomic-informed medicine is allowing us to improve our understanding of the molecular anatomy of NS and our ability to care for patients with NS. In this Core Curriculum, we review the specific genes and loci discovered in childhood NS, specifically NS of Mendelian origin, APOL1-associated NS in black patients, HLA region variants associated with steroid-sensitive NS, their biological impacts, prevalence across populations, and clinical correlates. We also review the fundamentals of genetic architecture of human disease, technologies, and analytic strategies that currently exist to discover disease-related genetic variations. A facility with the concepts and vocabulary of modern genomics and ability to interpret results of genetic studies are essential skills for nephrologists caring for children with NS. As such, we hope to empower them to understand the literature in this area, appropriately order genetic tests and accurately interpret the results, and consider how they may participate in or drive the next wave of genomic discoveries in NS.

Transthyretin amyloidosis: a phenocopy of hypertrophic cardiomyopathy

OBJECTIVES

Hypertrophic cardiomyopathy (HCM) is an inherited cardiac disorder that affects over one in 500 persons worldwide. The autosomal dominant transmission of HCM implies that many relatives are at risk for HCM associated morbidity and mortality, therefore genetic testing and counselling is of great importance. However, in only 50-60% of the patients a mutation is found, which hampers predictive genetic testing in relatives. In HCM patients in whom the causal mutation has not been identified (yet), phenocopies of HCM - i.e. diseases that mimic HCM - could be responsible for the HCM phenotype. One of the HCM phenocopies is transthyretin amyloidosis (ATTR), caused by mutations in the transthyretin (TTR) gene.

METHODS

From 697 HCM index patients referred to our cardiogenetics outpatient clinic and tested for HCM associated genes between January 1997 and December 2012, we selected the ones without a detected causal mutation (n = 345). In these patients, additional DNA analysis of the TTR gene was performed.

RESULTS

In four patients (1.2%), a TTR mutation was detected (E7G, V30M, T119M, V122I). The E7G mutation is probably a non-pathogenic mutation. The T119M mutation is a known TTR mutation, but does not cause a cardiac phenotype. So in two (0.6%) patients, TTR analysis identified the cause of their HCM.

CONCLUSIONS

ATTR should always be considered in patients with unexplained HCM, especially because of the great benefit of an early diagnosis regarding treatment and prognosis.

Laser-Induced Photic Injury Phenocopies Macular Dystrophy

OBJECTIVE

To describe the phenotypes associated with laser-induced retinal damage in children.

METHODS

Five patients with maculopathy and reduced visual acuity associated with laser pointer use were evaluated. Best-corrected visual acuity, retinal structure, and function were monitored with color fundus, infrared (IR), and red-free images, fundus autofluorescence (AF), spectral domain-optical coherence tomography (SD-OCT), and full-field electroretinography (ERG).

RESULTS

All five laser pointer injury patients had retinal lesions resembling a macular dystrophy (one bilateral and four unilateral). These lesions were irregular in shape but all had a characteristic dendritic appearance with linear streaks radiating from the lesion. Photoreceptor damage was present in all patients, but serial OCT monitoring showed that subsequent photoreceptor recovery occurred over time in the eyes of at least four patients. One patient also had bilateral pigment epithelial detachments (PED). Both hyper- and hypoautofluorecence were observed in the laser damage area.

CONCLUSIONS

In general, OCT and IR images are quite useful to diagnose laser damage, but AF is not as sensitive. Laser pointer damage in children can occasionally be misdiagnosed as a macular dystrophy disease, but the distinctive lesions and OCT features are helpful for differentiating laser damage from other conditions.

Brugada Phenocopy as a Dynamic Electrocardiographic Pattern during Acute Anterior Myocardial Infarction

Brugada phenocopies represent some unusual clinical cases with identical characteristics to Brugada syndrome (BrS) elicited by various clinical circumstances. We report the case of a woman exhibiting "Brugada Phenocopy" during an acute anterior myocardial infarction, highlighting differential diagnosis with true BrS and discussing possible mechanisms underlying its dynamic ECG pattern.

Pathway to a phenocopy: Heat stress effects in early embryogenesis

BACKGROUND

Heat shocks applied at the onset of gastrulation in early Drosophila embryos frequently lead to phenocopies of U-shaped mutants-having characteristic failures in the late morphogenetic processes of germband retraction and dorsal closure. The pathway from nonspecific heat stress to phenocopied abnormalities is unknown.

RESULTS

Drosophila embryos subjected to 30-min, 38 °C heat shocks at gastrulation appear to recover and restart morphogenesis. Post-heat-shock development appears normal, albeit slower, until a large fraction of embryos develop amnioserosa holes (diameters > 100 µm). These holes are positively correlated with terminal U-shaped phenocopies. They initiate between amnioserosa cells and open over tens of minutes by evading normal wound healing responses. They are not caused by tissue-wide increases in mechanical stress or decreases in cell-cell adhesion, but instead appear to initiate from isolated apoptosis of amnioserosa cells.

CONCLUSIONS

The pathway from heat shock to U-shaped phenocopies involves the opening of one or more large holes in the amnioserosa that compromise its structural integrity and lead to failures in morphogenetic processes that rely on amnioserosa-generated tensile forces. The proposed mechanism by which heat shock leads to hole initiation and expansion is heterochonicity, i.e., disruption of morphogenetic coordination between embryonic and extra-embryonic cell types.

Ancient association between cation leak channels and Mid1 proteins is conserved in fungi and animals

Neuronal resting potential can tune the excitability of neural networks, affecting downstream behavior. Sodium leak channels (NALCN) play a key role in rhythmic behaviors by helping set, or subtly changing neuronal resting potential. The full complexity of these newly described channels is just beginning to be appreciated, however. NALCN channels can associate with numerous subunits in different tissues and can be activated by several different peptides and second messengers. We recently showed that NALCN channels are closely related to fungal calcium channels, which they functionally resemble. Here, we use this relationship to predict a family of NALCN-associated proteins in animals on the basis of homology with the yeast protein Mid1, the subunit of the yeast calcium channel. These proteins all share a cysteine-rich region that is necessary for Mid1 function in yeast. We validate this predicted association by showing that the Mid1 homolog in Drosophila, encoded by the CG33988 gene, is coordinately expressed with NALCN, and that knockdown of either protein creates identical phenotypes in several behaviors associated with NALCN function. The relationship between Mid1 and leak channels has therefore persisted over a billion years of evolution, despite drastic changes to both proteins and the organisms in which they exist.