An Adolescent Boy With Hypoxia, Microscopic Hematuria, and Hypertension.

A 13-year-old boy presented with hypoxia, microscopic hematuria, and elevated blood pressures. Persistent microscopic hematuria and hypertension led to investigation of glomerular and non-glomerular causes of hematuria. After reviewing his clinical course, family history, and laboratory testing, an additional test was sent, revealing the diagnosis.

De novo variants in RNF213 are associated with a clinical spectrum ranging from Leigh syndrome to early-onset stroke.

PURPOSE: RNF213, encoding a giant E3 ubiquitin ligase, has been recognized for its role as a key susceptibility gene for moyamoya disease. Case reports have also implicated specific variants in RNF213 with an early-onset form of moyamoya disease with full penetrance. We aimed to expand the phenotypic spectrum of monogenic RNF213-related disease and to evaluate genotype-phenotype correlations. METHODS: Patients were identified through reanalysis of exome sequencing data of an unselected cohort of unsolved pediatric cases and through GeneMatcher or ClinVar. Functional characterization was done by proteomics analysis and oxidative phosphorylation enzyme activities using patient-derived fibroblasts. RESULTS: We identified 14 individuals from 13 unrelated families with (de novo) missense variants in RNF213 clustering within or around the Really Interesting New Gene (RING) domain. Individuals presented either with early-onset stroke (n = 11) or with Leigh syndrome (n = 3). No genotype-phenotype correlation could be established. Proteomics using patient-derived fibroblasts revealed no significant differences between clinical subgroups. 3D modeling revealed a clustering of missense variants in the tertiary structure of RNF213 potentially affecting zinc-binding suggesting a gain-of-function or dominant negative effect. CONCLUSION: De novo missense variants in RNF213 clustering in the E3 RING or other regions affecting zinc-binding lead to an early-onset syndrome characterized by stroke or Leigh syndrome.

Patent ductus arteriosus and coarctation of the aorta in association with PRDM6 variants.

Patent ductus arteriosus (PDA) and coarctation of the aorta (CoA) are relatively common congenital heart defects. Pathogenic variants in PRDM6, which encodes a smooth-muscle-cell-specific transcription factor, have now been etiologically associated with non-syndromic PDA. We present three patients with PDA and CoA found to harbor PRDM6 variants, including a novel, likely-pathogenic variant.

Phenotypes of undiagnosed adults with actionable OTC and GLA variants.

Inherited metabolic disorders (IMDs) are variably expressive, complicating identification of affected individuals. A genotype-first approach can identify individuals at risk for morbidity and mortality from undiagnosed IMDs and can lead to protocols that improve clinical detection, counseling, and management. Using data from 57,340 participants in two hospital biobanks, we assessed the frequency and phenotypes of individuals with pathogenic/likely pathogenic variants (PLPVs) in two IMD genes: GLA, associated with Fabry disease, and OTC, associated with ornithine transcarbamylase deficiency. Approximately 1 in 19,100 participants harbored an undiagnosed PLPV in GLA or OTC. We identified three individuals (2 male, 1 female) with PLPVs in GLA, all of whom were undiagnosed, and three individuals (3 female) with PLPVs in OTC, two of whom were undiagnosed. All three individuals with PLPVs in GLA (100%) had symptoms suggestive of mild Fabry disease, and one individual (14.2%) had an ischemic stroke at age 33, likely indicating the presence of classic disease. No individuals with PLPVs in OTC had documented hyperammonemia despite exposure to catabolic states, but all (100%) had chronic symptoms suggestive of attenuated disease, including mood disorders and migraines. Our findings suggest that GLA and OTC variants identified via a genotype-first approach are of high penetrance and that population screening of these genes can be used to facilitate stepwise phenotyping and appropriate care.

Combined PMM2-CDG and hereditary fructose intolerance in a patient with mild clinical presentation.

We report a patient with an extremely rare, combined diagnosis of PMM2-CDG and hereditary fructose intolerance (HFI). By comparing with other patients, under-galactosylation was identified as a feature of HFI. Fructose/sorbitol/sucrose restriction was initiated right afterwards. The patient is at the mild end of the PMM2-CDG spectrum, raising the question of sorbitol's role in the pathogenesis of PMM2-CDG and whether fructose/sorbitol/sucrose restriction could benefit other PMM2-CDG patients. Additionally, epalrestat, an emerging potential PMM2-CDG therapy, may benefit HFI patients.

Cryptophthalmos: associated syndromes and genetic disorders.

PURPOSE: Cryptophthalmos is a rare congenital condition caused by anomalous eyelid development where the eyelid folds do not develop or fail to separate. Cryptophthalmos can be unilateral or bilateral and can occur in isolation or as part of an underlying syndrome. We aim to identify genetic syndromes associated with cryptophthalmos to facilitate genetic diagnosis. METHODS: We performed a retrospective medical record review of all patients diagnosed with cryptophthalmos followed at a single center between 2000 and 2020. The analysis included medical history, clinical examination findings, and genetic testing results. RESULTS: Thirteen patients were included, 10 (77%) males, mean age of 2.4 years. Eight (61%) had bilateral cryptophthalmos, and 4 (31%) had complete cryptophthalmos. Associated ocular abnormalities included corneal opacities (13/13, 100%), upper eyelid colobomas (12/13, 92%), and microphthalmia/clinical anophthalmia (3/13, 23%). All cases of complete cryptophthalmos had bilateral disease. An underlying clinical or molecular diagnosis was identified in 10/13 (77%) cases, including Fraser syndrome (n = 5), amniotic band syndrome (n = 1), FREM1-related disease (n = 1), Goldenhar versus Schimmelpenning syndrome (n = 1), MOTA syndrome (n = 1), and CELSR2-related disease (n = 1). CONCLUSION: This is the first report of a possible association between cryptophthalmos and biallelic CELSR2 variants. Children with cryptophthalmos, especially those with extra-ocular involvement, should be referred for comprehensive genetic evaluation.

Perspectives of Rare Disease Experts on Newborn Genome Sequencing.

Importance: Newborn genome sequencing (NBSeq) can detect infants at risk for treatable disorders currently undetected by conventional newborn screening. Despite broad stakeholder support for NBSeq, the perspectives of rare disease experts regarding which diseases should be screened have not been ascertained. Objective: To query rare disease experts about their perspectives on NBSeq and which gene-disease pairs they consider appropriate to evaluate in apparently healthy newborns. Design, Setting, and Participants: This survey study, designed between November 2, 2021, and February 11, 2022, assessed experts' perspectives on 6 statements related to NBSeq. Experts were also asked to indicate whether they would recommend including each of 649 gene-disease pairs associated with potentially treatable conditions in NBSeq. The survey was administered between February 11 and September 23, 2022, to 386 experts, including all 144 directors of accredited medical and laboratory genetics training programs in the US. Exposures: Expert perspectives on newborn screening using genome sequencing. Main Outcomes and Measures: The proportion of experts indicating agreement or disagreement with each survey statement and those who selected inclusion of each gene-disease pair were tabulated. Exploratory analyses of responses by gender and age were conducted using t and χ2 tests. Results: Of 386 experts invited, 238 (61.7%) responded (mean [SD] age, 52.6 [12.8] years [range 27-93 years]; 126 [52.9%] women and 112 [47.1%] men). Among the experts who responded, 161 (87.9%) agreed that NBSeq for monogenic treatable disorders should be made available to all newborns; 107 (58.5%) agreed that NBSeq should include genes associated with treatable disorders, even if those conditions were low penetrance; 68 (37.2%) agreed that actionable adult-onset conditions should be sequenced in newborns to facilitate cascade testing in parents, and 51 (27.9%) agreed that NBSeq should include screening for conditions with no established therapies or management guidelines. The following 25 genes were recommended by 85% or more of the experts: OTC, G6PC, SLC37A4, CYP11B1, ARSB, F8, F9, SLC2A1, CYP17A1, RB1, IDS, GUSB, DMD, GLUD1, CYP11A1, GALNS, CPS1, PLPBP, ALDH7A1, SLC26A3, SLC25A15, SMPD1, GATM, SLC7A7, and NAGS. Including these, 42 gene-disease pairs were endorsed by at least 80% of experts, and 432 genes were endorsed by at least 50% of experts. Conclusions and Relevance: In this survey study, rare disease experts broadly supported NBSeq for treatable conditions and demonstrated substantial concordance regarding the inclusion of a specific subset of genes in NBSeq.

TOPORS as a novel causal gene for Joubert syndrome.

Joubert syndrome (JBTS) is a Mendelian disorder of the primary cilium defined by the clinical triad of hypotonia, developmental delay, and a distinct cerebellar malformation called the molar tooth sign. JBTS is inherited in an autosomal recessive, autosomal dominant, or X-linked recessive manner. Though over 40 genes have been identified as causal for JBTS, molecular diagnosis is not made in 30%-40% of individuals who meet clinical criteria. TOPORS encodes topoisomerase I-binding arginine/serine-rich protein, and homozygosity for a TOPORS missense variant (c.29C > A; p.(Pro10Gln)) was identified in individuals with the ciliopathy oral-facial-digital syndrome in two families of Dominican descent. Here, we report an additional proband of Dominican ancestry with JBTS found by exome sequencing to be homozygous for the identical p.(Pro10Gln) TOPORS missense variant. Query of the Mount Sinai BioMe biobank, which includes 1880 individuals of Dominican ancestry, supports a high carrier frequency of the TOPORS p.(Pro10Gln) variant in individuals of Dominican descent. Our data nominates TOPORS as a novel causal gene for JBTS and suggests that TOPORS variants should be considered in the differential of ciliopathy-spectrum disease in individuals of Dominican ancestry.

A mutational hotspot in AMOTL1 defines a new syndrome of orofacial clefting, cardiac anomalies, and tall stature.

AMOTL1 encodes angiomotin-like protein 1, an actin-binding protein that regulates cell polarity, adhesion, and migration. The role of AMOTL1 in human disease is equivocal. We report a large cohort of individuals harboring heterozygous AMOTL1 variants and define a core phenotype of orofacial clefting, congenital heart disease, tall stature, auricular anomalies, and gastrointestinal manifestations in individuals with variants in AMOTL1 affecting amino acids 157-161, a functionally undefined but highly conserved region. Three individuals with AMOTL1 variants outside this region are also described who had variable presentations with orofacial clefting and multi-organ disease. Our case cohort suggests that heterozygous missense variants in AMOTL1, most commonly affecting amino acid residues 157-161, define a new orofacial clefting syndrome, and indicates an important functional role for this undefined region.

Molecular diagnosis and novel genes and phenotypes in a pediatric thoracic insufficiency cohort.

Thoracic insufficiency syndromes are a genetically and phenotypically heterogeneous group of disorders characterized by congenital abnormalities or progressive deformation of the chest wall and/or vertebrae that result in restrictive lung disease and compromised respiratory capacity. We performed whole exome sequencing on a cohort of 42 children with thoracic insufficiency to elucidate the underlying molecular etiologies of syndromic and non-syndromic thoracic insufficiency and predict extra-skeletal manifestations and disease progression. Molecular diagnosis was established in 24/42 probands (57%), with 18/24 (75%) probands having definitive diagnoses as defined by laboratory and clinical criteria and 6/24 (25%) probands having strong candidate genes. Gene identified in cohort patients most commonly encoded components of the primary cilium, connective tissue, and extracellular matrix. A novel association between KIF7 and USP9X variants and thoracic insufficiency was identified. We report and expand the genetic and phenotypic spectrum of a cohort of children with thoracic insufficiency, reinforce the prevalence of extra-skeletal manifestations in thoracic insufficiency syndromes, and expand the phenotype of KIF7 and USP9X-related disease to include thoracic insufficiency.

TBX6 as a cause of a combined skeletal-kidney dysplasia syndrome.

TBX6 encodes transcription-factor box 6, a transcription factor critical to paraxial mesoderm segmentation and somitogenesis during embryonic development. TBX6 haploinsufficiency is believed to drive the skeletal and kidney phenotypes associated with the 16p11.2 deletion syndrome. Heterozygous and biallelic variants in TBX6 are associated with vertebral and rib malformations (TBX6-associated congenital scoliosis) and spondylocostal dysostosis, and heterozygous TBX6 variants are associated with increased risk of genitourinary tract malformations. Combined skeletal and kidney phenotypes in individuals harboring heterozygous or biallelic TBX6 variants are rare. Here, we present seven individuals with vertebral and rib malformations and structural kidney differences associated with heterozygous TBX6 gene deletion in trans with a hypomorphic TBX6 allele or biallelic TBX6 variants. Our case series highlights the association between TBX6 and both skeletal and kidney disease.

Interstitial deletion 4p15.32p16.1 and complex chromoplexy in a female proband with severe neurodevelopmental delay, growth failure and dysmorphism.

Complex chromosomal rearrangements involve the restructuring of genetic material within a single chromosome or across multiple chromosomes. These events can cause serious human disease by disrupting coding DNA and gene regulatory elements via deletions, duplications, and structural rearrangements. Here we describe a 5-year-old female with severe developmental delay, dysmorphic features, multi-suture craniosynostosis, and growth failure found to have a complex series of balanced intra- and inter-chromosomal rearrangements involving chromosomes 4, 11, 13, and X. Initial clinical studies were performed by karyotype, chromosomal microarray, and FISH with research-based short-read genome sequencing coupled with sanger sequencing to precisely map her breakpoints to the base pair resolution to understand the molecular basis of her phenotype. Genome analysis revealed two pathogenic deletions at 4p16.1-p15.32 and 4q31.1, accounting for her developmental delay and dysmorphism. We identified over 60 breakpoints, many with blunt ends and limited homology, supporting a role for non-homologous end joining in restructuring and resolution of the seminal chromoplexy event. We propose that the complexity of our patient's genomic rearrangements with a high number of breakpoints causes dysregulation of gene expression by three-dimensional chromatin interactions or topologically associating domains leading to growth failure and craniosynostosis. Our work supports an important role for genome sequencing in understanding the molecular basis of complex chromosomal rearrangements in human disease.

The current state of adult metabolic medicine in the United States: Results of a nationwide survey.

PURPOSE: Patients with inherited metabolic disorders (IMDs) now have improved health outcomes and increased survival into adulthood. There is scant evidence on managing adults with IMDs. We present an analysis of current care practices for adults with IMDs in the United States. METHODS: We created and distributed an online survey to US members of the Society of Inherited Metabolic Disorders. The survey addressed ambulatory care, acute management, and health care transition (HCT) practices of adults with IMDs. RESULTS: The survey was completed by 91 providers from 73 institutions. Most adult patients with IMDs receive lifelong care from a single metabolic clinician, predominantly in pediatric clinic settings. Adults receive comprehensive ambulatory metabolic care, but fewer trainees participate compared with pediatric visits. Most acute IMD management occurs in pediatric hospitals. Clinician comfort with HCT increased the frequency of HCT planning. Overall, all respondents felt that providing specialized care to adults with IMDs is high value. CONCLUSION: Our survey demonstrates the paucity of clinical resources dedicated to adult metabolic medicine. Care is fragmented and varies by medical system. Interest in HCT is robust but would benefit from standardized practices. Our findings reinforce the need for greater focus on adult metabolic medicine in the United States.

Delayed diagnosis and racial bias in children with genetic conditions.

As more therapeutics for genetic conditions become available, the need for timely and equitable genetic diagnosis has become urgent. Using clinical cases, we consider the health system-, provider-, and patient-level factors that contribute to the delayed diagnosis of genetic conditions in pediatric patients from minority populations, leading to health disparities between racial groups. We then provide suggestions to address these factors, with the aim of improving minority health and access to genetic care for all children.

Stankiewicz-Isidor syndrome: expanding the clinical and molecular phenotype.

PURPOSE: Haploinsufficiency of PSMD12 has been reported in individuals with neurodevelopmental phenotypes, including developmental delay/intellectual disability (DD/ID), facial dysmorphism, and congenital malformations, defined as Stankiewicz-Isidor syndrome (STISS). Investigations showed that pathogenic variants in PSMD12 perturb intracellular protein homeostasis. Our objective was to further explore the clinical and molecular phenotypic spectrum of STISS. METHODS: We report 24 additional unrelated patients with STISS with various truncating single nucleotide variants or copy-number variant deletions involving PSMD12. We explore disease etiology by assessing patient cells and CRISPR/Cas9-engineered cell clones for various cellular pathways and inflammatory status. RESULTS: The expressivity of most clinical features in STISS is highly variable. In addition to previously reported DD/ID, speech delay, cardiac and renal anomalies, we also confirmed preaxial hand abnormalities as a feature of this syndrome. Of note, 2 patients also showed chilblains resembling signs observed in interferonopathy. Remarkably, our data show that STISS patient cells exhibit a profound remodeling of the mTORC1 and mitophagy pathways with an induction of type I interferon-stimulated genes. CONCLUSION: We refine the phenotype of STISS and show that it can be clinically recognizable and biochemically diagnosed by a type I interferon gene signature.

A novel MBTPS2 variant associated with BRESHECK syndrome impairs sterol-regulated transcription and the endoplasmic reticulum stress response.

Ichthyosis follicularis, atrichia, and photophobia syndrome (IFAP syndrome) is a rare, X-linked disorder caused by pathogenic variants in membrane-bound transcription factor protease, site 2 (MBTPS2). Pathogenic MBTPS2 variants also cause BRESHECK syndrome, characterized by the IFAP triad plus intellectual disability and multiple congenital anomalies. Here we present a patient with ichthyosis, sparse hair, pulmonic stenosis, kidney dysplasia, hypospadias, growth failure, thrombocytopenia, anemia, bone marrow fibrosis, and chronic diarrhea found by research-based exome sequencing to harbor a novel, maternally inherited MBTPS2 missense variant (c.766 G>A; (p.Val256Leu)). In vitro modeling supports variant pathogenicity, with impaired cell growth in cholesterol-depleted media, attenuated activation of the sterol regulatory element-binding protein pathway, and failure to activate the endoplasmic reticulum stress response pathway. Our case expands both the genetic and phenotypic spectrum of BRESHECK syndrome to include a novel MBTPS2 variant and cytopenias, bone marrow fibrosis, and chronic diarrhea.

Hepatic Manifestations of Urea Cycle Disorders.

Content available: Author Interview and Audio Recording.