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.

The MAP3K7 gene: Further delineation of clinical characteristics and genotype/phenotype correlations.

Mitogen-activated protein 3 kinase 7 (MAP3K7) encodes the ubiquitously expressed transforming growth factor ß-activated kinase 1, which plays a crucial role in many cellular processes. Mutationsin the MAP3K7 gene have been linked to two distinct disorders: frontometaphyseal dysplasia type 2 (FMD2) and cardiospondylocarpofacial syndrome (CSCF). The fact that different mutations can induce two distinct phenotypes suggests a phenotype/genotype correlation, but no side-by-side comparison has been done thus far to confirm this. Here, we significantly expand the cohort and the description of clinical phenotypes for patients with CSCF and FMD2 who carry mutations in MAP3K7. Our findings support that in contrast to FMD2-causing mutations, CSCF-causing mutations in MAP3K7 have a loss-of-function effect. Additionally, patients with pathogenic mutations in MAP3K7 are at risk for (severe) cardiac disease, have symptoms associated with connective tissue disease, and we show overlap in clinical phenotypes of CSCF with Noonan syndrome (NS). Together, we confirm a molecular fingerprint of FMD2- versus CSCF-causing MAP3K7 mutations and conclude that mutations in MAP3K7 should be considered in the differential diagnosis of patients with syndromic congenital cardiac defects and/or cardiomyopathy, syndromic connective tissue disorders, and in the differential diagnosis of NS.

Near complete deletion of KMT2D in a college student.

Pathogenic variants in KMT2D are typically associated with Kabuki syndrome (KS), a rare multisystem disorder. KS is characterized by facial dysmorphisms, intellectual disability, skeletal and dermatoglyphic differences, and poor growth. Seventy percent of individuals with clinically diagnosed KS have a confirmed pathogenic variant in KMT2D or less commonly KDM6A. The majority of mutations found in KMT2D are de novo nonsense or frameshift, with deletions and duplications rarely reported in the literature. Here, we present the case of near complete deletion of KMT2D in a college student with normal intelligence discovered via exome sequencing and EpiSign methylation testing. This case provides evidence that large deletions in KMT2D are compatible with normal intelligence and presents EpiSign as a method for discovering molecular causes of KS not identified by traditional molecular testing.

Pitfalls and challenges in genetic test interpretation: An exploration of genetic professionals experience with interpretation of results.

The interpretation of genetic testing results is subject to error. This observational study illustrates examples of pitfalls and challenges in interpretation of genetic testing results as reported by genetics professionals. We surveyed genetics professionals to describe interpretation challenges, the types of variants that were involved, and the reported clinical impact of misconception of a test result. Case studies were then collected from a select group to further explore potential causes of misunderstanding. A total of 83% of survey respondents were aware of at least one instance of genetic test misinterpretation. Both professionals with and without formal training in genetics were challenged by test reports, and variants of unknown significance were most frequently involved. Case submissions revealed that interpretation pitfalls extend beyond variant classification analyses. Inferred challenges in case submissions include lack of genetic counseling, unclear wording of reports, and suboptimal communication among providers. Respondents and case submitters noted that incorrect interpretation can trigger unnecessary follow-up tests and improperly alter clinical management. Further research is needed to validate and quantify large-scale data regarding challenges of genetic results interpretation.

Neonatal hydrocephalus: an atypical presentation of malignant infantile osteopetrosis.

PURPOSE: Autosomal recessive osteopetrosis has a variable presentation, most commonly including failure to thrive, hypocalcemia, seizures, hepatosplenomegaly, hydrocephalus, vision or hearing loss, and cytopenias. Multiple symptoms are usually seen at presentation. The variability of presentation often delays diagnosis and subsequent treatment. Here, we present a case of an infant with this condition who initially presented with triventricular hydrocephalus with Chiari I malformation. This alone is not a common presentation of this disease, and we present this case to highlight autosomal recessive osteopetrosis as a potential diagnosis in infants presenting with hydrocephalus and discuss the other associated symptoms, management, and prognosis of this condition. CASE REPORT: The patient was a full-term infant with a routine newborn period. At 6 months, the infant had macrocephaly and frontal bossing with a bulging fontanelle. She was found to have hydrocephalus with moderate ventriculomegaly involving the third and lateral ventricles with an associated Chiari 1 malformation. The infant was asymptomatic at the time. The infant was promptly referred to neurosurgery and underwent an uncomplicated ventriculoperitoneal shunt placement. Post-operative X-rays showed increased density of the skull with other bone changes suggestive of autosomal recessive osteopetrosis. Subsequent lab work and imaging studies were consistent with this condition. The diagnosis was confirmed by genetic testing, and the patient has undergone treatment with hematopoietic stem cell transplant. CONCLUSION: Hydrocephalus is a common feature of this condition, typically seen in conjunction with other systemic symptoms and laboratory findings. Our patient had a limited initial presentation of triventricular hydrocephalus with Chiari I malformation and was otherwise clinically asymptomatic. There is limited literature of such a presentation, and we highlight this case to increase awareness, as timely diagnosis of these patients is critical for treatment and future outcomes.

Repeatedly in Rhabdomyolysis.

ABSTRACT: Repeated presentations of a rare symptom in a patient should make a physician stop and evaluate for rare conditions. This is a report of a teenager with multiple episodes of rhabdomyolysis and weakness. He was eventually diagnosed as having McArdle muscular dystrophy, or glycogen storage disease type V. His rhabdomyolysis has been severe, with a creatinine kinase level of >320,000 U/L, myoglobinuria, transaminitis, and elevated bilirubin. He has a low threshold for triggering rhabdomyolysis, such as doing an hour of aerobic exercise 2 days in a row. McArdle disease is a glycogen storage disorder in which the skeletal muscle cannot convert glycogen to glucose. Unlike other glycogen storage disorders, McArdle muscular dystrophy only affects the skeletal muscle, sparing the brain and visceral organs, leading to a vague phenotype. These patients have exercise intolerance, muscle cramps, and rhabdomyolysis. Many patients report loading with simple carbohydrates before exercise, as they have learned that this can increase their stamina. The vague symptoms can lead to decades of delay in diagnosis and significant mismanagement. Rhabdomyolysis is the most dangerous sign of McArdle disease, and it can lead to acute kidney injury, resulting in renal failure requiring dialysis in the severest cases.Rhabdomyolysis has numerous causes, but when it is recurrent, especially with seemingly insignificant triggers, one needs to develop a broader differential and pursue advanced testing. This testing can include specific exercise tests, genetic sequencing, and muscle biopsy. This case report will guide the clinician through the process of evaluating recurrent rhabdomyolysis, working through the differential diagnosis and testing options.1.

Novel SGCE Mutation in a Patient With Myoclonus-Dystonia: A Case Report.

Objectives: Characterize the presentation, workup, and management of SGCE myoclonus-dystonia, a rare genetic condition, in a patient with atypical presenting symptoms and no family history of movement abnormalities. Methods: A woman with myoclonus and dystonia was identified based on clinical history and physical examination. Workup was conducted to determine the cause of her symptoms, including whole-exome sequencing. Myoclonus-dystonia is associated with more than 100 distinct mutations in MYC/DYT-SGCE that account for only half of the total myoclonus-dystonia patients. As such, this case required intensive genetic analyses rather than screening only for a small subset of well-characterized mutations. Results: Childhood onset myoclonus and worsening dystonia with age were identified in a young woman. She underwent screening for common causes of twitching movements, followed by whole-exome sequencing which identified a de novo novel variant in the SGCE gene, resulting in a diagnosis of SGCE myoclonus-dystonia. Discussion: Myoclonus-dystonia should be considered in patients with symptoms of head and upper extremity myoclonus early in life, especially with co-occurring dystonia, even in the absence of a family history of similar symptoms. Diagnosis of this condition should take place using sequencing, as new mutations continue to be discovered.

MFSD7c functions as a transporter of choline at the blood-brain barrier.

Mutations in the orphan transporter MFSD7c (also known as Flvcr2), are linked to Fowler syndrome. Here, we used Mfsd7c knockout (Mfsd7c-/-) mice and cell-based assays to reveal that MFSD7c is a choline transporter at the blood-brain barrier (BBB). We performed comprehensive metabolomics analysis and detected differential changes of metabolites in the brains and livers of Mfsd7c-/-embryos. Particularly, we found that choline-related metabolites were altered in the brains but not in the livers of Mfsd7c-/- embryos. Thus, we hypothesized that MFSD7c regulates the level of choline in the brain. Indeed, expression of human MFSD7c in cells significantly increased choline uptake. Interestingly, we showed that choline uptake by MFSD7c is greatly increased by choline-metabolizing enzymes, leading us to demonstrate that MFSD7c is a facilitative transporter of choline. Furthermore, single-cell patch clamp analysis showed that the import of choline by MFSD7c is electrogenic. Choline transport function of MFSD7c was shown to be conserved in vertebrates, but not in yeasts. We demonstrated that human MFSD7c is a functional ortholog of HNM1, the yeast choline importer. We also showed that several missense mutations identified in patients exhibiting Fowler syndrome had abolished or reduced choline transport activity. Mice lacking Mfsd7c in endothelial cells of the central nervous system suppressed the import of exogenous choline from blood but unexpectedly had increased choline levels in the brain. Stable-isotope tracing study revealed that MFSD7c was required for exporting choline derived from lysophosphatidylcholine in the brain. Collectively, our work identifies MFSD7c as a choline exporter at the BBB and provides a foundation for future work to reveal the disease mechanisms of Fowler syndrome.

Midterm Outcomes of Heart Transplantation in Children With Genetic Disorders.

BACKGROUND: Many congenital heart diseases (CHD) are associated with genetic defects. Children with complex CHD often have heart failure requiring heart transplant. Given the broad spectrum of genetic pathologies and dearth of transplants performed in these children, little is known regarding their outcomes. METHODS: We conducted a retrospective review of heart transplants performed at a high-volume center from 2007 to 2021. Patients were separated into pathogenic molecular and copy number variants, aneuploidies, and variants of uncertain significance, and compared with patients without known genetic diagnoses. Variables included genetic diagnoses, bridge-to-transplant approach, preoperative comorbidities, operative characteristics, and postoperative complications. Outcomes included intensive care unit-free days to 28 days, hospital mortality, survival, rejection, retransplantation, and educational status at latest follow-up. RESULTS: In all, 223 patients received transplants over the study period: 9.9% (22 of 223) had pathogenic molecular variants; 4.5% (10 of 223) had copy number variants; 1.8% (4 of 223) had aneuploidies; and 9% (20 of 223) had variants of uncertain significance. The most common anomalies were Turner syndrome (n = 3) and 22q11.2 deletion syndrome (n = 2). Children with aneuploidies had higher rates of hepatic dysfunction and hypothyroidism, whereas children with pathogenic copy number variants had higher rates of preoperative gastrostomy and stroke. Children with aneuploidies were intubated longer after transplant, with greater need for reintubation, and had the fewest intensive care unit-free days. Mortality and mean survival did not differ. At median follow-up of 4.4 years (range, 1.9 to 8.8), 89.7% of survivors (26 of 29) with pathogenic anomalies were attending or had graduated school. CONCLUSIONS: Despite more preoperative comorbidities, midterm outcomes after heart transplant in children with genetic syndromes and disorders are promising.

Genetic testing hearing loss: The challenge of non syndromic mimics.

Congenital hearing loss is a common cause of morbidity in early childhood. There are multiple reasons for congenital hearing impairment, with genetic contribution becoming increasingly recognized. Sensorineural hearing loss has classically been viewed as either syndromic or non-syndromic. With the advent of DNA sequencing technology such as NextGen sequencing, a subcategory has arisen, that of non-syndromic mimics (NSM)s. NSMs present initially as isolated hearing loss but as the patient ages other phenotypes become evident. Early diagnosis of these conditions is imperative as patients may suffer significant morbidity and mortality from complications from their hearing loss syndrome. An example is QT prolongation in Jervell and Lange-Nielsen Syndrome. The need for genetic testing and proper genetic counseling is necessary for patients with hearing loss and testing should be done as early in life as possible.

Novel variants in KAT6B spectrum of disorders expand our knowledge of clinical manifestations and molecular mechanisms.

The phenotypic variability associated with pathogenic variants in Lysine Acetyltransferase 6B (KAT6B, a.k.a. MORF, MYST4) results in several interrelated syndromes including Say-Barber-Biesecker-Young-Simpson Syndrome and Genitopatellar Syndrome. Here we present 20 new cases representing 10 novel KAT6B variants. These patients exhibit a range of clinical phenotypes including intellectual disability, mobility and language difficulties, craniofacial dysmorphology, and skeletal anomalies. Given the range of features previously described for KAT6B-related syndromes, we have identified additional phenotypes including concern for keratoconus, sensitivity to light or noise, recurring infections, and fractures in greater numbers than previously reported. We surveyed clinicians to qualitatively assess the ways families engage with genetic counselors upon diagnosis. We found that 56% (10/18) of individuals receive diagnoses before the age of 2 years (median age = 1.96 years), making it challenging to address future complications with limited accessible information and vast phenotypic severity. We used CRISPR to introduce truncating variants into the KAT6B gene in model cell lines and performed chromatin accessibility and transcriptome sequencing to identify key dysregulated pathways. This study expands the clinical spectrum and addresses the challenges to management and genetic counseling for patients with KAT6B-related disorders.

Inherited cause of in utero digital malformations.

Amniotic band sequence (ABS) is common birth defect of incompletely understood origin. Here we describe a case of ABS in a child with paternally inherited Ehlers-Danlos syndrome, vascular type (vEDS). This is the third reported instance of ABS associated with paternally inherited vEDS in the medical literature. The two main theories of ABS formation are the extrinsic and intrinsic. The extrinsic theory states that placental tears form fibrous cords that wrap around the fetus; the intrinsic states that poor vascularisation in the fetus leads to necrosis of distal extremities. We believe this case supports extrinsic theory as it shows that as an amnion weakened by vEDS in fetal components is associated with ABS.