American Journal of Medical Genetics Part A最新文献

We report an 87-year-old female with a history of intellectual disability, severe speech impairment and behavioral issues. She was globally delayed in childhood. In adolescence, she had hallucinations, behavioral issues and was institutionalized. Her behavioral issues were treated, and her medical and behavioral course was stable until her 80's when she began to decline cognitively. She died at age 87. Exome sequencing revealed a novel predicted damaging missense variant (c.1913T>G; p.Met638Arg; NM_001136196.2) in the gene encoding Transportin-2 (TNPO2). Heterozygous variants in TNPO2 have been recently associated with an intellectual developmental disorder with hypotonia, impaired speech, and dysmorphic facies (IDDHISD; MIM:619556). Postmortem pathological examination of her brain revealed focal neuronal depletion in the dentate gyrus, CA1, and hilar regions of the hippocampus. These findings are consistent with human gene expression data showing normal to increased expression of TNPO2 in the dentate gyrus and CA1 region of the hippocampus. We suggest that the p.(Met638Arg) variant in TNPO2 is potentially disease-causing and associated with IDDHISD.

The objective of this study was to evaluate the EHR user experience and satisfaction of clinicians in the medical genetics and genomics field. An anonymous survey was sent through genetic related listservs and LinkedIn to a broad range of genetics clinicians including physicians, advanced practice providers, and genetic counselors. Results showed a wide range of satisfaction levels among all types of genetic clinicians, reflecting the need for improved genetic EHR functionalities. Despite available EHR training being reported as helpful by most individuals who had completed some, the utilization was low. There was a striking difference between internally and externally sent test results regarding how difficult they are to find and import into clinical documentation. Despite available EHR tools, a high manual labor burden occurs for most during the documentation process. There is demand for more genetic functionalities, some which exist but institutions may not have implemented these features. Genomics EHR modules can improve EHR user experiences. Key themes for EHR usability include institutional support, interoperability and integration, ease of data access, streamlined documentation, centralized workflows, and clinical decision support. Future evaluation is needed to determine how to improve the interoperability of genetic testing with EHRs and increase accessibility to genetic related EHR functionalities.

Whilst biallelic variants in RTEL1 are an established cause of telomere biology disorder (TBD), the significance of heterozygous variants has been more challenging to establish. In this nationwide analysis, we describe 18 individuals with heterozygous pathogenic RTEL1 variants from seven families. All were identified during routine clinical genetic investigation for a variety of indications. Each family carried a different variant in RTEL1. Eight individuals had been diagnosed with a TBD-related disease (five with a hematological disorder, four with pulmonary fibrosis, overlap of one). No cases of clinically significant liver fibrosis had been detected. Cutaneous features of dyskeratosis congenita (abnormal skin pigmentation, oral leukoplakia, nail dysplasia and/or prematurely gray hair) were observed in four individuals. Telomere length (lymphocyte) was measured in nine individuals from six families and was below the 1st percentile in eight individuals. These cases illustrate the wide spectrum of disease and reduced penetrance associated with pathogenic RTEL1 variants, providing a real-world perspective on previous findings from research cohorts. We discuss the challenges surrounding incidental findings, clinical surveillance, and reproductive counseling in this context.

SLC30A9 mutations are linked to Birk-Landau-Perez syndrome, which is characterized by neurodevelopmental and renal disease, thought to result from impaired zinc homeostasis. In this report, we describe a patient with a homozygous likely pathogenic SLC30A9 variant with atypical chorio-retinal degeneration, suggesting retinal involvement in SLC30A9-associated diseases. The patient has bilateral sensorineural hearing loss, developmental delay, intellectual disability, abnormal balance, and Tourette syndrome. Ophthalmic manifestations include vascular attenuation, optic disc pallor, and pigmentation. In addition, the patient is noted to have high myopia. Our case highlights the importance of broad genetic testing in diagnosing rare multi-systemic disorders. Further research into the molecular mechanisms by which SLC30A9 results in photoreceptor disease is essential to understand its role in retinal degeneration and to develop potential therapeutic strategies.

A molecular diagnosis is currently achievable in approximately 50% of patients assessed by clinical geneticists at tertiary care centres. Next-Generation Sequencing Panels contain a defined group of genes associated with a clinically defined set of phenotypes. Most clinical sequencing providers streamline their wet-bench workflows by sequencing the entire exome or genome, followed by targeted bioinformatic extraction of variant data from a pre-specified gene set. Thus, additional data on these patients remain available but are only reviewed by special request. We interrogated clinical-grade sequencing data on two out of three affected members of a family with childhood-onset adrenal insufficiency in whom an autosomal recessive condition was suspected. Review of clinome data identified heterozygosity for CYP11A1 variants c.644T>C; p.(Phe215Ser) and c.1187G>A; p.(Arg396Lys) in both affected sibs. Long-read whole genome sequencing of the proband showed these variants were in trans, confirming compound heterozygosity and resolving the molecular etiology of the clinical diagnosis.

Translocation of newly synthesized proteins into the lumen of the endoplasmic reticulum (ER) is mediated by signal peptide recognition and cleavage. Here we report an individual with Simpson-Golabi-Behmel syndrome (SGBS) bearing a GPC3 missense variant at the signal peptide cleavage site of the glypican-3 protein. The c.71C>T; p.(Ala24Val) alteration in the key -1 position of the cleavage greatly reduces cleavage of the signal peptide, resulting in failure of the protein to efficiently exit the ER, and impaired glycosylation. Functional characterization of two other engineered variants at this position-one predicted to permit cleavage and the other to prevent it-corroborates our findings. This case highlights the potential for missense variants within the signal peptide cleavage site to underlie genetic disorders, and reinforces the idea that many of the missense variants in GPC3 that cause SGBS reside in motifs with high functional relevance to the processing and maturation of glypican-3.

Smith-Kingsmore syndrome (SKS) is a rare autosomal dominant condition characterized by neurodevelopmental differences, macrocephaly/megalencephaly, describable facial features, sleep-wake abnormalities, hyperphagia, and overgrowth. SKS is caused by pathogenic gain-of-function variants in MTOR which lead to hyperactivation of the mTOR pathway. In this review, we discuss the history, epidemiology, molecular basis, clinical features, and management considerations for Smith-Kingsmore syndrome. In addition, we provide insight on early developmental milestones through a report on 14 individuals with a confirmed diagnosis of SKS. Among these individuals, 8/12 (67%) achieved crawling at an average age of 23 months, 9/14 (64%) achieved walking with an average age of 32 months, 5/9 (56%) achieved a pincer grasp at an average age of 23 months, 8/12 (67%) achieved the ability to use a device or utensil with an average age of 3.4 years, 10/13 (77%) achieved babbling at an average age of 20 months, 8/14 (57%) achieved their first word at an average age of 34 months, and 4/14 (29%) achieved the use of short phrases at an average age of 4.6 years. This review highlights advances in characterizing the natural history of SKS since it was first described 12 years ago and the need for additional research to inform genotype-phenotype correlations and targeted therapies to support individuals with SKS.

Biallelic pathogenic variants in AKR1D1 cause Δ4-3-oxosteroid 5β-reductase deficiency, disrupt bile acid synthesis, and result in Congenital Bile Acid Synthesis defect type 2 (CBAS2). CBAS2 presents in infancy with cholestasis, coagulopathy, and failure to thrive. We report an infant who unexpectedly died at age 8 weeks with hepatic dysfunction and intracerebral hemorrhage. Characteristic of CBAS2, postmortem biochemical findings showed near-absent primary bile acids and accumulation of atypical bile acid intermediates. Subsequent genetic testing found compound heterozygous AKR1D1 variants: NM_005989.3:c.[593C>T];[782G>A], p.(Pro198Leu);(Arg261His). This highlights the diagnostic challenge posed by bile acid synthesis disorders, the need for early diagnosis, and the potential for fatal outcomes without early intervention. Given the treatable nature of CBAS2, we advocate for expanded newborn screening or for rapid targeted bile acid or genetic screening in infants presenting with cholestasis, prolonged jaundice, or hyperbilirubinemia.

Rahman syndrome (HIST1H1E-related neurodevelopmental syndrome, OMIM #617537) is a rare autosomal-dominant condition caused by truncating variants in the C-terminal domain of the HIST1H1E gene. It is characterized by macrocephaly, hypotonia, craniofacial anomalies, and multisystem anomalies. Although multisystem involvement has been increasingly described, respiratory manifestations remain sparsely documented. We report a female infant with mosaic HIST1H1E truncation (c.435dupC; p.Thr146Hisfs*50) who presented with severe mixed sleep apnea secondary to laryngomalacia, requiring two airway surgeries and multidisciplinary management. Despite surgical intervention, polysomnography demonstrated persistent mixed apneas, suggesting both structural and central components. Brain MRI revealed nonspecific ischemic changes that could contribute to the neurological phenotype. To contextualize this observation, we reviewed 70 published cases of Rahman syndrome. Respiratory involvement was reported in only 13.5% (neonatal respiratory distress), 2.8% (upper-airway anomalies), and 1.4% (sleep-disordered breathing), frequencies comparable to those in the general population, although most reports lacked systematic respiratory evaluation. These findings suggest that respiratory morbidity may be under-evaluated rather than absent in Rahman syndrome. The combination of hypotonia, craniofacial restriction, and possible brain-stem dysregulation provides a plausible pathophysiologic substrate for both central and obstructive apnea. We recommend considering airway assessment and polysomnography in affected individuals presenting with stridor, desaturations, or sleep-related breathing difficulties. This case further expands the phenotypic spectrum of HIST1H1E-related disorders and represents the first documented example of mosaicism associated with this condition.