A patient with a novel pathogenic variant in COL5A1 exhibiting prominent vascular and cardiac features.

The Ehlers-Danlos Syndromes (EDS) are a group of inherited connective tissue disorders with a worldwide prevalence of 1 in 2500 to 1 in 5000 births irrespective of sex or ethnicity. Fourteen subtypes of Ehlers-Danlos Syndrome (EDS) have been described, each with characteristic phenotypes and associated genes. Pathogenic variants in COL5A1 and COL5A2 cause the classical EDS subtypes. Pathogenic variants in COL3A1 cause vascular EDS. In this case report, we describe a patient with a phenotype resembling that of vascular EDS, caused by a novel pathogenic variant in COL5A1.

Importance of Family History in the Era of Exome Analysis: A Report of a Family with Multiple Concurrent Genetic Diseases.

Multiple familial diseases in a single patient often present with overlapping symptomatology that confers difficulty in delineating a clinical diagnosis. Pedigree analysis has been a long-standing practice in the field of medical genetics to discover familial diseases. In recent years, whole exome sequencing (WES) has proven to be a useful tool for aiding physicians in diagnosing and understanding disease etiology. This report shows that pedigree analysis and WES are co-dependent processes in establishing diagnoses in a family with 4 different genetic disorders: Birt-Hogg-Dubé Syndrome, RRM2B-related mitochondrial disease, CDC73-related primary hyperparathyroidism, and familial prostate cancer.

Bi-allelic Alterations in AEBP1 Lead to Defective Collagen Assembly and Connective Tissue Structure Resulting in a Variant of Ehlers-Danlos Syndrome.

AEBP1 encodes the aortic carboxypeptidase-like protein (ACLP) that associates with collagens in the extracellular matrix (ECM) and has several roles in development, tissue repair, and fibrosis. ACLP is expressed in bone, the vasculature, and dermal tissues and is involved in fibroblast proliferation and mesenchymal stem cell differentiation into collagen-producing cells. Aebp1-/- mice have abnormal, delayed wound repair correlating with defects in fibroblast proliferation. In this study, we describe four individuals from three unrelated families that presented with a unique constellation of clinical findings including joint laxity, redundant and hyperextensible skin, poor wound healing with abnormal scarring, osteoporosis, and other features reminiscent of Ehlers-Danlos syndrome (EDS). Analysis of skin biopsies revealed decreased dermal collagen with abnormal collagen fibrils that were ragged in appearance. Exome sequencing revealed compound heterozygous variants in AEBP1 (c.1470delC [p.Asn490_Met495delins(40)] and c.1743C>A [p.Cys581∗]) in the first individual, a homozygous variant (c.1320_1326del [p.Arg440Serfs∗3]) in the second individual, and a homozygous splice site variant (c.1630+1G>A) in two siblings from the third family. We show that ACLP enhances collagen polymerization and binds to several fibrillar collagens via its discoidin domain. These studies support the conclusion that bi-allelic pathogenic variants in AEBP1 are the cause of this autosomal-recessive EDS subtype.

Physician-directed genetic screening to evaluate personal risk for medically actionable disorders: a large multi-center cohort study.

BACKGROUND: The use of proactive genetic screening for disease prevention and early detection is not yet widespread. Professional practice guidelines from the American College of Medical Genetics and Genomics (ACMG) have encouraged reporting pathogenic variants that confer personal risk for actionable monogenic hereditary disorders, but only as secondary findings from exome or genome sequencing. The Centers for Disease Control and Prevention (CDC) recognizes the potential public health impact of three Tier 1 actionable disorders. Here, we report results of a large multi-center cohort study to determine the yield and potential value of screening healthy individuals for variants associated with a broad range of actionable monogenic disorders, outside the context of secondary findings. METHODS: Eligible adults were offered a proactive genetic screening test by health care providers in a variety of clinical settings. The screening panel based on next-generation sequencing contained up to 147 genes associated with monogenic disorders within cancer, cardiovascular, and other important clinical areas. Sequence and intragenic copy number variants classified as pathogenic, likely pathogenic, pathogenic (low penetrance), or increased risk allele were considered clinically significant and reported. Results were analyzed by clinical area and severity/burden of disease using chi-square tests without Yates' correction. RESULTS: Among 10,478 unrelated adults screened, 1619 (15.5%) had results indicating personal risk for an actionable monogenic disorder. In contrast, only 3.1 to 5.2% had clinically reportable variants in genes suggested by the ACMG version 2 secondary findings list to be examined during exome or genome sequencing, and 2% had reportable variants related to CDC Tier 1 conditions. Among patients, 649 (6.2%) were positive for a genotype associated with a disease of high severity/burden, including hereditary cancer syndromes, cardiovascular disorders, or malignant hyperthermia susceptibility. CONCLUSIONS: This is one of the first real-world examples of specialists and primary care providers using genetic screening with a multi-gene panel to identify health risks in their patients. Nearly one in six individuals screened for variants associated with actionable monogenic disorders had clinically significant results. These findings provide a foundation for further studies to assess the role of genetic screening as part of regular medical care.

Impact of integrated translational research on clinical exome sequencing.

PURPOSE: Exome sequencing often identifies pathogenic genetic variants in patients with undiagnosed diseases. Nevertheless, frequent findings of variants of uncertain significance necessitate additional efforts to establish causality before reaching a conclusive diagnosis. To provide comprehensive genomic testing to patients with undiagnosed disease, we established an Individualized Medicine Clinic, which offered clinical exome testing and included a Translational Omics Program (TOP) that provided variant curation, research activities, or research exome sequencing. METHODS: From 2012 to 2018, 1101 unselected patients with undiagnosed diseases received exome testing. Outcomes were reviewed to assess impact of the TOP and patient characteristics on diagnostic rates through descriptive and multivariate analyses. RESULTS: The overall diagnostic yield was 24.9% (274 of 1101 patients), with 174 (15.8% of 1101) diagnosed on the basis of clinical exome sequencing alone. Four hundred twenty-three patients with nondiagnostic or without access to clinical exome sequencing were evaluated by the TOP, with 100 (9% of 1101) patients receiving a diagnosis, accounting for 36.5% of the diagnostic yield. The identification of a genetic diagnosis was influenced by the age at time of testing and the disease phenotype of the patient. CONCLUSION: Integration of translational research activities into clinical practice of a tertiary medical center can significantly increase the diagnostic yield of patients with undiagnosed disease.

Poirier-Bienvenu neurodevelopmental syndrome: A report of a patient with a pathogenic variant in CSNK2B with abnormal linear growth.

Casein kinase 2-related disorders have been linked to pathogenic variants in CSNK2A1 and CSNK2B. CSNK2B-related disease is predominantly associated with neurodevelopmental abnormalities affecting cognition; however, the extent of the phenotype associated with CSNK2B pathogenic variants is yet to be fully explored. Here, we describe a patient with features suggestive of Poirier-Bienvenu neurodevelopmental syndrome, harboring a novel CSNK2B pathogenic variant. We also report that the linear growth abnormalities could be a recurrent presentation in patients with this syndrome and suggest the effect of growth hormone therapy in our patient's stature.

Chimerism involving a RB1 pathogenic variant in monochorionic dizygotic twins with twin-twin transfusion syndrome.

We report the first case of blood chimerism involving a pathogenic RB1 variant in naturally conceived monochorionic-dizygotic twins (MC/DZ) with the twin-twin-transfusion syndrome (TTTS), presumably caused by the exchange of stem-cells. Twin A developed bilateral retinoblastoma at 7 months of age. Initial genetic testing identified a de novo RB1 pathogenic variant, with a 20% allelic ratio in both twins' blood. Subsequent genotyping of blood and skin confirmed dizygosity, with the affected twin harboring the RB1 pathogenic variant in skin and blood, and the unaffected twin carrying the variant only in blood.

Biparental Inheritance of Mitochondrial DNA in Humans.

Although there has been considerable debate about whether paternal mitochondrial DNA (mtDNA) transmission may coexist with maternal transmission of mtDNA, it is generally believed that mitochondria and mtDNA are exclusively maternally inherited in humans. Here, we identified three unrelated multigeneration families with a high level of mtDNA heteroplasmy (ranging from 24 to 76%) in a total of 17 individuals. Heteroplasmy of mtDNA was independently examined by high-depth whole mtDNA sequencing analysis in our research laboratory and in two Clinical Laboratory Improvement Amendments and College of American Pathologists-accredited laboratories using multiple approaches. A comprehensive exploration of mtDNA segregation in these families shows biparental mtDNA transmission with an autosomal dominantlike inheritance mode. Our results suggest that, although the central dogma of maternal inheritance of mtDNA remains valid, there are some exceptional cases where paternal mtDNA could be passed to the offspring. Elucidating the molecular mechanism for this unusual mode of inheritance will provide new insights into how mtDNA is passed on from parent to offspring and may even lead to the development of new avenues for the therapeutic treatment for pathogenic mtDNA transmission.

A practical approach to adult-onset white matter diseases, with illustrative cases.

AIM: To evaluate five illustrative cases and perform a literature review to identify and describe a working approach to adult-onset white matter diseases (WMD). STATE OF THE ART: Inherited WMD are a group of disorders often seen in childhood. In adulthood, progressive WMDs are rare, apart from the common nonspecific causes of hypertension and other cerebrovascular diseases. The pattern of WMDs on neuroimaging can be an important clue to the final diagnosis. Due to the adoption of a combined clinical-imaging-laboratory approach, WMD is becoming better recognised, in addition to the rapidly evolving field of genomics in this area. CLINICAL IMPLICATIONS: While paediatric WMDs have a well-defined and literature-based clinical-laboratory approach to diagnosis, adult-onset WMDs remain an important, pathologically diverse, radiographic phenotype, with different and distinct neuropathologies among the various subtypes of WMD. Adult-onset WMDs comprise a wide collection of both acquired and inherited aetiologies. While severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) neurological complications are emerging, we are as yet unaware of it causing WMD outside of post-anoxic changes. It is important to recognise WMD as a potentially undefined acquired or genetic syndrome, even when extensive full genome testing reveals variants of unknown significance. FUTURE DIRECTIONS: We propose a combined clinical-imaging-laboratory approach to WMD and continued exploration of acquired and genetic factors. Adult-onset WMD, even given this approach, can be challenging because hypertension is often comorbid. Therefore, we propose that undiagnosed patients with WMD be entered into multicentre National Organisation for Rare Diseases registries to help researchers worldwide make new discoveries that will hopefully translate into future cures.

Expansion of the clinical spectrum associated with AARS2-related disorders.

Biallelic pathogenic variants in AARS2, a gene encoding the mitochondrial alanyl-tRNA synthetase, result in a spectrum of findings ranging from infantile cardiomyopathy to adult-onset progressive leukoencephalopathy. In this article, we present three unrelated individuals with novel compound heterozygous pathogenic AARS2 variants underlying diverse clinical presentations. Patient 1 is a 51-year-old man with adult-onset progressive cognitive, psychiatric, and motor decline and leukodystrophy. Patient 2 is a 34-year-old man with childhood-onset progressive tremor followed by the development of polyneuropathy, ataxia, and mild cognitive and psychiatric decline without leukodystrophy on imaging. Patient 3 is a 57-year-old woman with childhood-onset tremor and nystagmus which preceded dystonia, chorea, ataxia, depression, and cognitive decline marked by cerebellar atrophy and white matter disease. These cases expand the clinical heterogeneity of AARS2-related disorders, given that the first and third case represent some of the oldest known survivors of this disease, the second is adult-onset AARS2-related neurological decline without leukodystrophy, and the third is biallelic AARS2-related disorder involving a partial gene deletion.

Molecular characterization of known and novel ACVR1 variants in phenotypes of aberrant ossification.

Diffuse idiopathic skeletal hyperostosis (DISH) is a disorder principally characterized by calcification and ossification of spinal ligaments and entheses. Fibrodysplasia ossificans progressiva (FOP) is a rare autosomal dominant disabling disorder characterized by progressive ossification of skeletal muscle, fascia, tendons, and ligaments. These conditions manifest phenotypic overlap in the ossification of tendons and ligaments. We describe herein a patient with DISH, exhibiting heterotopic ossification of the posterior longitudinal ligament where clinical whole exome sequencing identified a variant within ACVR1, a gene implicated in FOP. This variant, p.K400E, is a novel variant, not identified previously, and occurs in a highly conserved region across orthologs. We used sequence-based predicative algorithms, molecular modeling, and molecular dynamics simulations, to test the potential for p.K400E to alter the structure and dynamics of ACVR1. We applied the same modeling and simulation methods to established FOP variants, to identify the detailed effects that they have on the ACVR1 protein, as well as to act as positive controls against which the effects of p.K400E could be evaluated. Our in silico molecular analyses support p.K400E as altering the behavior of ACVR1. In addition, functional testing to measure the effect of this variant on BMP-pSMAD 1/5/8 target genes was carried out which revealed this variant to cause increased ID1 and Msx2 expression compared with the wild-type receptor. This analysis supports the potential for the variant of uncertain significance to contribute to the patient's phenotype.

A sleep modulated Channelopathy: a novel CACNA1A pathogenic variant identified in episodic Ataxia type 2 and a potential link to sleep alleviated migraine.

BACKGROUND: To describe a patient with sleep alleviated episodic ataxia type 2 with a novel CACNA1A pathogenic variant and provide a possible link to sleep responsive migraine. CASE PRESENTATION: A 26-year-old woman with recurrent attacks of dizziness, nausea, vomiting, ataxia and dysarthria presented for a possible diagnosis of vestibular migraine. Unique to her attacks was if she could fall asleep for as little as 15 min the spells would subside. If however she remained awake the attacks would continue unabated. A presumed diagnosis of episodic ataxia type 2 was made and she became attack free on acetazolamide without recurrence. Genetic testing demonstrated a novel pathogenic variant in CACNA1A on chromosome 19. This pathogenic variant has not been previously reported in the literature and is suggested to truncate the CACNA1A polypeptide by introducing a premature stop codon. CONCLUSION: A case of episodic ataxia type 2 with a novel pathogenic variant in CACNA1A is described. Interestingly, the patient's symptoms would completely alleviate with sleep which suggests a sleep modulated channelopathy. The mechanisms by which sleep could potentially alter this pathogenic variant are hypothesized. A potential link to sleep alleviated migraine is suggested. Further study of this novel pathogenic variant may help us understand not only how sleep can modulate episodic ataxia type 2, but also migraine.

Glycine Amidinotransferase (GATM), Renal Fanconi Syndrome, and Kidney Failure.

Background For many patients with kidney failure, the cause and underlying defect remain unknown. Here, we describe a novel mechanism of a genetic order characterized by renal Fanconi syndrome and kidney failure.Methods We clinically and genetically characterized members of five families with autosomal dominant renal Fanconi syndrome and kidney failure. We performed genome-wide linkage analysis, sequencing, and expression studies in kidney biopsy specimens and renal cells along with knockout mouse studies and evaluations of mitochondrial morphology and function. Structural studies examined the effects of recognized mutations.Results The renal disease in these patients resulted from monoallelic mutations in the gene encoding glycine amidinotransferase (GATM), a renal proximal tubular enzyme in the creatine biosynthetic pathway that is otherwise associated with a recessive disorder of creatine deficiency. In silico analysis showed that the particular GATM mutations, identified in 28 members of the five families, create an additional interaction interface within the GATM protein and likely cause the linear aggregation of GATM observed in patient biopsy specimens and cultured proximal tubule cells. GATM aggregates-containing mitochondria were elongated and associated with increased ROS production, activation of the NLRP3 inflammasome, enhanced expression of the profibrotic cytokine IL-18, and increased cell death.Conclusions In this novel genetic disorder, fully penetrant heterozygous missense mutations in GATM trigger intramitochondrial fibrillary deposition of GATM and lead to elongated and abnormal mitochondria. We speculate that this renal proximal tubular mitochondrial pathology initiates a response from the inflammasome, with subsequent development of kidney fibrosis.

Genomic Observations of a Rare/Pathogenic SMAD3 Variant in Loeys⁻Dietz Syndrome 3 Confirmed by Protein Informatics and Structural Investigations.

Background and objectives: Loeys-Dietz syndrome 3, also known as aneurysms--osteoarthritis syndrome, is an autosomal dominant genetic connective tissue disease caused by pathogenic variants in SMAD3, a transcription factor involved in TGF-ß signaling. This disorder is characterized by early-onset osteoarthritis and arterial aneurysms. Common features include scoliosis, uvula abnormalities, striae, and velvety skin. Materials and Methods: The pathogenicity of a variant of uncertain significance in the SMAD3 gene was evaluated (variant c.220C > T) through personalized protein informatics and molecular studies. Results: The case of a 44-year-old male, who was originally presumed to have Marfan syndrome, is presented. An expanded gene panel determined the probable cause to be a variant in SMAD3, c.220C > T (p.R74W). His case was complicated by a history of stroke, but his phenotype was otherwise characteristic for Loeys-Dietz syndrome 3. Conclusion: This case emphasizes the importance of comprehensive genetic testing to evaluate patients for connective tissue disorders, as well as the potential benefit of utilizing a protein informatics platform for the assessment of variant pathogenicity.

Anticipation in a family with primary familial brain calcification caused by an SLC20A2 variant.

AIM OF THE STUDY: To describe a family with primary familial brain calcification (PFBC) due to SLC20A2 variant showing possible genetic anticipation. MATERIALS AND METHODS: We conducted historical, genealogical, clinical, and radiologic studies of a family with PFBC. Clinical evaluations including neurological examination and head computed tomography (CT) scans of a proband and her father were performed. They provided additional information regarding other family members. To identify a causative gene variant, we performed whole-exome sequencing for the proband followed by segregation analysis in other affected members using direct sequencing. RESULTS: In this family, nine affected members were identified over four generations. The proband suffered from chronic daily headache including thunderclap headache. We identified an SLC20A2 (c.509delT, p.(Leu170*)) variant in three affected members over three generations. Interestingly, the age of onset became younger as the disease passed through successive generations, suggestive of genetic anticipation. CONCLUSIONS AND CLINICAL IMPLICATIONS: For clinical purpose, it is important to consider thunderclap headache and genetic anticipation in PFBC caused by SLC20A2 variants. Further investigation is required to validate our observation.

Late onset asymptomatic pancreatic neuroendocrine tumor - A case report on the phenotypic expansion for MEN1.

BACKGROUND: Multiple endocrine neoplasia type 1 (MEN1) is a hereditary cancer syndrome associated with several endocrine as well as non-endocrine tumors and is caused by mutations in the MEN1 gene. Primary hyperparathyroidism affects the majority of MEN1 individuals by age 50 years. Additionally, MEN1 mutations trigger familial isolated hyperparathyroidism. We describe a seemingly unaffected 76-year-old female who presented to our Genetics Clinic with a family history of primary hyperparathyroidism and the identification of a pathogenic MEN1 variant. CASE PRESENTATION: The patient was a 76 year-old woman who appeared to be unaffected. She had a family history of a known MEN1 pathogenic variant. Molecular testing for the known MEN1 mutation c.1A > G, as well as, biochemical testing, MRI of the brain and abdomen were all performed using standard methods. Molecular testing revealed our patient possessed the MEN1 pathogenic variant previously identified in her two offspring. Physical exam revealed red facial papules with onset in her seventies, involving her cheeks, nose and upper lip. Formerly, she was diagnosed with rosacea by a dermatologist and noted no improvement with treatment. Clinically, these lesions appeared to be facial angiofibromas. Brain MRI was normal. However, an MRI of her abdomen revealed a 1.5 cm lesion at the tail of the pancreas with normal adrenal glands. Glucagon was mildly elevated and pancreatic polypeptide was nearly seven times the upper limit of the normal range. The patient underwent spleen sparing distal pancreatectomy and subsequent pathology was consistent with a well-differentiated pancreatic neuroendocrine tumor (pNET). CONCLUSIONS: Age-related penetrance and variable expressivity are well documented in families with MEN1. It is thought that nearly all individuals with MEN1 manifest disease by age 40. We present a case of late-onset MEN1 in the absence of the most common feature, primary hyperparathyroidism, but with the presence of a pNET and cutaneous findings. This family expands the phenotype associated with the c.1A > G pathogenic variant and highlights the importance of providing comprehensive assessment of MEN1 mutation carriers in families that at first blush may appear to have isolated hyperparathyroidism.

Silent Tyrosinemia Type I Without Elevated Tyrosine or Succinylacetone Associated with Liver Cirrhosis and Hepatocellular Carcinoma.

Tyrosinemia type I (TYRSN1, TYR I) is caused by fumarylacetoacetate hydrolase (FAH) deficiency and affects approximately one in 100,000 individuals worldwide. Pathogenic variants in FAH cause TYRSN1, which induces cirrhosis and can progress to hepatocellular carcinoma (HCC). TYRSN1 is characterized by the production of a pathognomonic metabolite, succinylacetone (SUAC) and is included in the Recommended Uniform Screening Panel for newborns. Treatment intervention is effective if initiated within the first month of life. Here, we describe a family with three affected children who developed HCC secondary to idiopathic hepatosplenomegaly and cirrhosis during infancy. Whole exome sequencing revealed a novel homozygous missense variant in FAH (Chr15(GRCh38):g.80162305A>G; NM_000137.2:c.424A > G; NP_000128.1:p.R142G). This novel variant involves the catalytic pocket of the enzyme, but does not result in increased SUAC or tyrosine, making the diagnosis of TYRSN1 problematic. Testing this novel variant using a rapid, in vivo somatic mouse model showed that this variant could not rescue FAH deficiency. In this case of atypical TYRSN1, we show how reliance on SUAC as a primary diagnostic test can be misleading in some patients with this disease. Augmentation of current screening for TYRSN1 with targeted sequencing of FAH is warranted in cases suggestive of the disorder.