Molecular Genetics & Genomic Medicine最新文献

Background: MECP2 variants cause X-chromosome-linked rare developmental syndromes. Typically, the mutation is sporadic, occurs in females and is fatal in men. Accurate genetic and clinical diagnostics are considered essential for the management of symptoms and the development of new treatments. These aims may be difficult to reach before more is known about factors resulting in highly variable clinical pictures among patients carrying the same MECP2 variant. We describe the clinical picture of two brothers carrying the same MECP2 variant and compare them with cases published in the literature.

Methods: Most of the MECP2 mutations are known to be de novo mutations, which is why the recurrence of the mutation in the couple's other children is unlikely. Unexpectedly, our routine genetic testing revealed a 23-year-old man (P1) and his younger brother (P2) to carry the same hemizygous pathogenic missense variant c.419C>T, p.(Ala140Val) (transcript NM_004992.3) of MECP2, which was found to be inherited from their presumably asymptomatic mother. Thus, further clinical evaluation and comparison with literature cases was considered necessary.

Results: The P1 has a severe syndromic intellectual disorder (ID), whereas his brother has a substantially milder ID predominantly limited to problems in verbal skills. Neither P1 nor his younger brother has been diagnosed with Rett syndrome. The P1 (unlike his younger brother) has several lingual, social and motor difficulties; disruptive behavior was the most difficult symptom to treat. P1's response to several medical and non-medical treatment trials has remained inadequate, thus requiring the patient to be hospitalised for a long time. The literature review revealed that apart from our family, there are five other families with more than one male carrying the same MECP2 p.Ala140Val mutation, such as P1 and P2. The phenotypes of all 24 men from us (n = 2) and others (n = 22) carrying the same, presumably non-lethal mutation show great variability.

Conclusions: The p.Ala140Val mutation of MECP2 in males is associated with a rare X-chromosomal developmental disorder with highly variable phenotypes. Further studies are needed to better understand all those influencing factors that can explain phenotypic differences within the same genotype to find optimal medicinal therapies.

Background: Sensorineural hearing loss (SNHL) is a frequent manifestation of syndromic inherited retinal diseases (IRDs), exemplified by the very rare form of autosomal-dominant Leber congenital amaurosis with early onset deafness (LCAEOD; OMIM #617879). LCAEOD was first described in 2017 in four families segregating heterozygous missense mutations in TUBB4B, a gene encoding a β-tubulin isotype. To date, only eight more families with similar TUBB4B-associated sensorineural disease (SND) have been reported. Most cases harbored missense variants affecting the same amino acid (Arg391) and only three families segregated variants involving different residues (Tyr310, Arg390).

Methods: We performed whole-exome sequencing and a full ophthalmological and audiological examination of the affected members in an Italian family segregating syndromic IRD with early onset deafness.

Results: We identified a novel, ultra-rare, disease-causing variant in TUBB4B (NM_006088.6:c.1049A>C) that replaces a highly conserved lysine with threonine at amino acid position 350. The functional impact of the Lys350Thr substitution was supported by protein structure modeling studies. The variant segregates in the family members presenting retinal disease with early onset SNHL. Detailed ophthalmological assessment of the affected subjects diagnosed a progressive cone-rod dystrophy.

Conclusion: These findings expand the limited number of disease-causing TUBB4B variants, corroborating their association with SND forms, and suggest Lys350 is an important residue for β-tubulin function. Interestingly, our results demonstrate that TUBB4B mutations can cause cone-dominated retinal phenotypes.

Background: Rapid Whole Genome Sequencing (rWGS) is increasingly being used in neonatal intensive care units, as there is growing evidence that rare singe gene disorders present in the neonatal period and early identification can change management. While the diagnostic utility is increased with this broad testing, the possibility of unexpected findings also increases significantly. Here, we present a patient found to have three distinct genetic conditions through rWGS testing, with significant psychosocial and health consequences.

Methods and results: This case report describes a patient who was identified with a form of chondrodysplasia punctata, as well as incidental findings of MECP2-related disorder and Jacobs' syndrome. To our knowledge, this is one of the first documented cases of triple genetic diagnoses in the literature, underscoring the expanding clinical utility of rWGS.

Conclusion: Our patient represents a unique example of the utility of rWGS in the NICU setting. As two of the three conditions were unexpected results, his case is an important reminder of the possibility of unexpected findings for both providers and families. His case demonstrates the importance of pretest counseling and consenting processes, particularly in an acute setting. It also will add to our understanding of MECP2 variant presentations in males in the future.

Background: The activin A receptor type 2A gene (ACVR2A) plays an important role in normal gestation, particularly in decidualization, trophoblastic invasion, and placentation. Although several studies have investigated the association between ACVR2A maternal variants and preeclampsia (PE) susceptibility; however, controversial results were obtained. Moreover, in none of the previous studies, the role of ACVR2A fetal variants was explored. The aim of the present study was to investigate the role of ACVR2A rs1424954 and rs1424941 polymorphisms in PE susceptibility considering the impact of both fetal and maternal genotypes.

Methods: For genotyping of ACVR2A rs1424954 and rs1424941, we performed TP-ARMS-PCR on 600 samples, including 400 peripheral blood samples from preeclamptic and normal women and 200 umbilical cord blood samples from each group of pregnant women.

Results: Regarding rs1424954, only the fetal genotypes were associated with an increased risk of PE in both dominant and recessive inheritance models (OR = 2.88, 95% CI: 1.58-5.25, p = 0.0005; and OR = 2.43, 95% CI: 1.21-4.87, p = 0.012; respectively). For ACVR2A rs1424941variant, both maternal and fetal heterozygote genotypes were associated with PE susceptibility (OR = 1.57, 95% CI: 1.02-2.04, p = 0.04; and OR = 1.90, 95% CI: 1.02-3.54, p = 0.04; respectively).

Conclusion: The present study confirmed the role of fetal ACVR2A polymorphisms in PE pathogenesis for the first time. However, replicated studies in diverse ethnicities are necessary to confirm the role of fetal genotype on susceptibility to PE.

Background: Cerebellar ataxia, mental retardation, and dysequilibrium (CAMRQ) syndrome is a rare neurodevelopmental disorder characterized by non-progressive cerebellar ataxia, intellectual disability, and cerebellar atrophy. Despite its rarity, CAMRQ syndrome poses significant challenges due to its heterogeneous genetic etiology and complex clinical presentation. This study details the evolving clinical phenotype over 7 years in a male with CAMRQ4 syndrome caused by an in-frame deletion variant in ATP8A2 gene.

Methods: A detailed clinical evaluation was performed, accompanied by tests and imaging studies. Clinical and genetic investigations, including segregation analysis, were carried out to confirm the pathogenicity of the identified variant. The evolving clinical phenotype of the patient, including developmental delay, cerebellar ataxia, and hand-foot crawling, was thoroughly investigated.

Results: A 10-year-old male patient with CAMRQ syndrome exhibited typical clinical manifestations including impaired motor coordination, cognitive impairment, and balance disturbances. Genetic analysis revealed a homozygous in-frame deletion variant (c.1286_1288delAGA) in the ATP8A2 gene, implicating ATP8A2 in the pathogenesis of CAMRQ syndrome. This variant was predicted to be likely pathogenic and deleterious, in accordance with its segregation in affected family members. Our findings expand the mutational spectrum of ATP8A2-associated CAMRQ syndrome and underscore the importance of comprehensive genetic testing in diagnosing rare neurological disorders.

Conclusion: The identification of an in-frame deletion variant in the ATP8A2 gene enhances our understanding of CAMRQ syndrome and highlights the phenotypic variability of the disorder. Our study contributes to the elucidation of CAMRQ syndrome by identifying a novel genetic variant and elucidating its clinical and genetic implications. Further research is warranted to advance our understanding of CAMRQ syndrome and to improve patient care and management strategies.

Background: PHARC syndrome, a rare autosomal recessive neurodegenerative disorder caused by mutations in the ABHD12 gene, is characterized by demyelinating polyneuropathy, hearing loss, ataxia, retinitis pigmentosa (RP), and early-onset cataracts. If patients are first diagnosed in the ophthalmology department, they are easily misdiagnosed as having RP or Usher syndrome. This study aimed to identify the genetic etiology and determine the clinical diagnosis of a Chinese family with suspected PHARC syndrome.

Method: Comprehensive ophthalmic examinations and systemic evaluations were conducted to confirm the phenotype. The genotype was identified through Whole Exome Sequencing (WES), and the current literature was reviewed understand better manifestations of PHARC syndrome related to pathogenic variants.

Results: The principal symptoms of the proband comprised profound sensorineural hearing loss since childhood, severe visual impairment, congenital cataracts, cone-rod dystrophy, and ataxia. WES revealed that the proband carried a compound heterozygous variant in the ABHD12 gene: M1, a known nonsense variation c.477G > A (p.Trp159Ter); and M2, a novel copy number variant with a deletion of approximately 18.10 Kbp in chromosome 20p11.21 (seq[GRCh38]del(20) (p11.21)chr20:g. 25302218_25320318del), covering exons 4-12 of the ABHD12 gene. The literature review indicated that there were 65 patients with PHARC from 30 different families. All clinical information of the described patients with PHARC syndrome and all known mutations associated with the disease to date were compiled.

Conclusion: This study expands the spectrum of pathogenic variants and phenotype for PHARC syndrome and suggests genetic testing is necessary for a definitive diagnosis of PHARC syndrome.

Background: Individuals with a germline CDKN2A pathogenic variant (PV) have an increased lifetime risk of melanoma and pancreatic cancer. It is unknown whether the CDKN2A PV impacts quality of life (QoL). Therefore we aimed to assess QoL and psychological distress in families affected by the PV.

Methods: This cross-sectional study included confirmed carriers and those with a 50% likelihood of carrying the PV (at-risk carriers) under cancer surveillance who were invited to complete a one-time questionnaire. Both confirmed and at-risk carriers are offered skin surveillance, whereas only confirmed carriers aged 40 years or older can participate in pancreatic surveillance.

Results: In total, 59/247 (24%) individuals under skin surveillance only (skin surveillance group) and 188/290 (65%) individuals under both skin and pancreatic cancer surveillance (pancreatic surveillance group) responded. In both surveillance groups, health-related QoL and general distress levels were within the general population norms. However, more than 40% of all study participants reported melanoma-related distress. Pancreatic cancer-related distress was experienced by 45% of the pancreatic surveillance group. Determinants of cancer-related distress were a first-degree relative with melanoma or pancreatic cancer, increased cancer risk perception, and poor general health perception. Over 80% of the participants felt that the benefits of cancer surveillance outweigh the disadvantages.

Conclusion: In conclusion, confirmed and at-risk carriers of the CDKN2A PV under cancer surveillance experienced similar levels of QoL and general distress compared to the general population. However, cancer-related worry was substantial in this population. These findings can help identify individuals who may benefit from psychological support.

Background: Alport syndrome involves chronic progressive kidney failure and extrarenal organ damage caused by COL4A3, COL4A4, and COL4A5 mutations.

Methods: We initially discerned a COL4A3 splicing mutation via next-generation sequencing. Next, we used bioinformatics, renal biopsy pathology, and an in vitro minigene experiment. Complementary analysis of clinical data was carried out, and we explored the expression and function of the variants to verify their pathogenicity.

Results: A splicing mutation (c.687 + 1G > T) in COL4A3 was found in a Chinese family. Bioinformatics analysis revealed its impact on splicing, causing a translational frameshift, which was confirmed by an in vitro minigene assay. The proband's glomerular basement membrane displayed reduced type IV collagen α3, α4, and α5 chains, with some absent, suggesting disruption of collagen IV trimers in the glomerular basement membrane, potentially damaging the glomerular filtration barrier.

Conclusion: We present a novel finding of a previously unreported c.687 + 1G > T mutation in COL4A3 that disrupts transcription and translation, impairing α3α4α5 (IV) chain formation, altering the integrity of the glomerular basement membrane, causing hereditary Alport syndrome. This discovery enriches the genetic map of Alport syndrome, aiding in clinical genetic guidance, and enhancing the efficacy of prenatal testing.

Background: Biallelic pathogenic variants in the FUCA1 gene are associated with fucosidosis. This report describes a 4-year-old boy presenting with psychomotor regression, spasticity, and dystonic postures.

Methods and results: Trio-based whole exome sequencing revealed two previously unreported loss-of-function variants in the FUCA1 gene. Brain magnetic resonance imaging (MRI) findings included corpus callosum hypoplasia, white matter hypomyelination, and alterations in the globus pallidi, alongside markedly reduced cortical thickness.

Conclusions: These findings suggest that cortical atrophy may occur in the early stages of fucosidosis. Early diagnosis is imperative for genetic counseling, timely investigations, and initiating early therapeutic interventions to potentially mitigate more extensive brain involvement.