A Deep Intronic Splice Variant in COL1A1 Causing Osteogenesis Imperfecta Type II.

Osteogenesis imperfecta (OI) is a rare disease, hallmarked by bone fragility, multiple fractures, and deformities, and is commonly caused by pathogenic variants in the genes encoding type I collagen. Type II OI is the most severe form and is lethal in the perinatal period. Here, we report recurrence of perinatal lethal OI in two fetuses due to parental mosaicism for a deep intronic pathogenic variant at c.

Heterozygous Beta-Thalassaemia in Pregnancy: Two Rare Causes of Severe Fetal Anemia Requiring Intrauterine Blood Transfusions.

Aim: In this article, we present two cases of severe fetal hemolytic anemia based on a beta-thalassaemia trait inherited from a single parent.

Results: These cases, presented at 20 and 28 weeks' gestation, necessitated intra-uterine blood transfusions. This occurrence is remarkable because it challenges the common assumption that beta-thalassaemia typically has no prenatal implications regarding fetal anemia.

Loss-of-Function Variants in as Modifying Factors in Beta-Thalassemia.

It is well known that modifiers play a role in ameliorating or exacerbating disease phenotypes in patients and carriers of recessively inherited disorders such as sickle cell disease and thalassemia. Here, we give an overview of the literature concerning a recently described association in carriers of Loss-of-Function variants with a beta-thalassemia-like phenotype including the characteristic elevated levels of HbA. That acts as modifier in beta-thalassemia carriers became evident from three reported cases in whom combined heterozygosity of and gene variants was observed to resemble a mild beta-thalassemia intermedia phenotype.

Machine Learning-Based Prediction of Hemoglobinopathies Using Complete Blood Count Data.

Background: Hemoglobinopathies, the most common inherited blood disorder, are frequently underdiagnosed. Early identification of carriers is important for genetic counseling of couples at risk. The aim of this study was to develop and validate a novel machine learning model on a multicenter data set, covering a wide spectrum of hemoglobinopathies based on routine complete blood count (CBC) testing.

Atypical Progeria Primarily Manifesting as Premature Cardiac Valvular Disease Segregates with -Gene Variants.

Mutations in the -gene can cause a variety of 'laminopathies'. These laminopathies are associated with a range of phenotypes, including disorders affecting the adipose tissue, peripheral nerves, the heart, such as dilated cardiomyopathy and conduction system abnormalities, and less commonly, progeroid disorders. This case series describes two families in which two novel LMNA-gene variants were identified, and who presented with an atypical progeroid phenotype with primarily premature aortic and mitral valve stenosis.

Reduced kinase function in two ultra-rare TNNI3K variants in families with congenital junctional ectopic tachycardia.

Genetic missense variants in TNNI3K, encoding troponin-I interacting kinase, have been associated with dilated cardiomyopathy (DCM) and observed in families with supraventricular tachycardias (SVT). Previously, a family harboring the TNNI3K-c.1615A > G (p.

The arrhythmogenic cardiomyopathy phenotype associated with PKP2 c.1211dup variant.

Background: The arrhythmogenic cardiomyopathy (ACM) phenotype, with life-threatening ventricular arrhythmias and heart failure, varies according to genetic aetiology. We aimed to characterise the phenotype associated with the variant c.1211dup (p.

Reclassification of a likely pathogenic Dutch founder variant in KCNH2; implications of reduced penetrance.

Background: Variants in KCNH2, encoding the human ether a-go-go (hERG) channel that is responsible for the rapid component of the cardiac delayed rectifier K+ current (IKr), are causal to long QT syndrome type 2 (LQTS2). We identified eight index patients with a new variant of unknown significance (VUS), KCNH2:c.2717C > T:p.

Biallelic loss of LDB3 leads to a lethal pediatric dilated cardiomyopathy.

Autosomal dominant variants in LDB3 (also known as ZASP), encoding the PDZ-LIM domain-binding factor, have been linked to a late onset phenotype of cardiomyopathy and myofibrillar myopathy in humans. However, despite knockout mice displaying a much more severe phenotype with premature death, bi-allelic variants in LDB3 have not yet been reported. Here we identify biallelic loss-of-function variants in five unrelated cardiomyopathy families by next-generation sequencing.

The Phenotypic Continuum of -Related Disorders.

Background And Objectives: is associated with a broad spectrum of predominantly neurologic disorders, which continues to expand beyond the initially defined phenotypes of alternating hemiplegia of childhood, rapid-onset dystonia parkinsonism, and cerebellar ataxia, areflexia, pes cavus, optic atrophy, sensorineural hearing loss syndrome. This phenotypic variability makes it challenging to assess the pathogenicity of an variant found in an undiagnosed patient. We describe the phenotypic features of individuals carrying a pathogenic/likely pathogenic variant and perform a literature review of all variants published thus far in association with human neurologic disease.

The hemoglobinopathies, molecular disease mechanisms and diagnostics.

Hemoglobinopathies are the most common monogenic disorders in the world with an ever increasing global disease burden each year. As most hemoglobinopathies show recessive inheritance carriers are usually clinically silent. Programmes for preconception and antenatal carrier screening, with the option of prenatal diagnosis are considered beneficial in many endemic countries.

Biallelic variants in CENPF causing a phenotype distinct from Strømme syndrome.

Biallelic loss-of-function (LoF) variants in CENPF gene are responsible for Strømme syndrome, a condition presenting with intestinal atresia, anterior ocular chamber anomalies, and microcephaly. Through an international collaboration, four individuals (three males and one female) carrying CENPF biallelic variants, including two missense variants in homozygous state and four LoF variants, were identified by exome sequencing. All individuals had variable degree of developmental delay/intellectual disability and microcephaly (ranging from -2.

Adapting the ACMG/AMP variant classification framework: A perspective from the ClinGen Hemoglobinopathy Variant Curation Expert Panel.

Accurate and consistent interpretation of sequence variants is integral to the delivery of safe and reliable diagnostic genetic services. To standardize the interpretation process, in 2015, the American College of Medical Genetics and Genomics (ACMG) and the Association for Molecular Pathology (AMP) published a joint guideline based on a set of shared standards for the classification of variants in Mendelian diseases. The generality of these standards and their subjective interpretation between laboratories has prompted efforts to reduce discordance of variant classifications, with a focus on the expert specification of the ACMG/AMP guidelines for individual genes or diseases.

PPA2-associated sudden cardiac death: extending the clinical and allelic spectrum in 20 new families.

Purpose: Biallelic hypomorphic variants in PPA2, encoding the mitochondrial inorganic pyrophosphatase 2 protein, have been recently identified in individuals presenting with sudden cardiac death, occasionally triggered by alcohol intake or a viral infection. Here we report 20 new families harboring PPA2 variants.

Methods: Synthesis of clinical and molecular data concerning 34 individuals harboring five previously reported PPA2 variants and 12 novel variants, 11 of which were functionally characterized.

The Evolving Role of Next-Generation Sequencing in Screening and Diagnosis of Hemoglobinopathies.

During the last few years, next-generation sequencing (NGS) has undergone a rapid transition from a research setting to a clinical application, becoming the method of choice in many clinical genetics laboratories for the detection of disease-causing variants in a variety of genetic diseases involving multiple genes. The hemoglobinopathies are the most frequently found Mendelian inherited monogenic disease worldwide and are composed of a complex group of disorders frequently involving the inheritance of more than one abnormal gene. This review aims to present the role of NGS in both screening and pre- and post-natal diagnostics of the hemoglobinopathies, and the added value of NGS is discussed based on the results described in the literature.

Usefulness of NGS for Diagnosis of Dominant Beta-Thalassemia and Unstable Hemoglobinopathies in Five Clinical Cases.

Unstable hemoglobinopathies (UHs) are rare anemia disorders (RADs) characterized by abnormal hemoglobin (Hb) variants with decreased stability. UHs are therefore easily precipitating, causing hemolysis and, in some cases, leading to dominant beta-thalassemia (dBTHAL). The clinical picture of UHs is highly heterogeneous, inheritance pattern is dominant, instead of recessive as in more prevalent major Hb syndromes, and may occur .

Identification of known and unknown genes associated with mitral valve prolapse using an exome slice methodology.

Purpose: Although a familial distribution has been documented, the genetic aetiology of mitral valve prolapse (MVP) is largely unknown, with only four genes identified so far: , , and . The aim of this study was to evaluate the genetic yield in known causative genes and to identify possible novel genes associated with MVP using a heart gene panel based on exome sequencing.

Methods: Patients with MVP were referred for genetic counselling when a positive family history for MVP was reported and/or Barlow's disease was diagnosed.

Ankyrin-B dysfunction predisposes to arrhythmogenic cardiomyopathy and is amenable to therapy.

Arrhythmogenic cardiomyopathy (ACM) is an inherited arrhythmia syndrome characterized by severe structural and electrical cardiac phenotypes, including myocardial fibrofatty replacement and sudden cardiac death. Clinical management of ACM is largely palliative, owing to an absence of therapies that target its underlying pathophysiology, which stems partially from our limited insight into the condition. Following identification of deceased ACM probands possessing ANK2 rare variants and evidence of ankyrin-B loss of function on cardiac tissue analysis, an ANK2 mouse model was found to develop dramatic structural abnormalities reflective of human ACM, including biventricular dilation, reduced ejection fraction, cardiac fibrosis, and premature death.

From diagnostic yield to clinical impact: a pilot study on the implementation of prenatal exome sequencing in routine care.

Purpose: Exome sequencing (ES) is an efficient tool to diagnose genetic disorders postnatally. Recent studies show that it may have a considerable diagnostic yield in fetuses with structural anomalies on ultrasound. We report on the clinical impact of the implementation of prenatal ES (pES) for ongoing pregnancies in routine care.