Objective
Congenital hydrocephalus is an important birth defect, the genetics of which remains incompletely understood. To date, only 4 genes are known to cause Mendelian diseases in which congenital ...hydrocephalus is the main or sole clinical feature, 2 X‐linked (L1CAM and AP1S2) and 2 autosomal recessive (CCDC88C and MPDZ). In this study, we aimed to determine the genetic etiology of familial congenital hydrocephalus with the assumption that these cases represent Mendelian forms of the disease.
Methods
Exome sequencing combined, where applicable, with positional mapping.
Results
We identified a likely causal mutation in the majority of these families (21 of 27, 78%), spanning 16 genes, none of which is X‐linked. Ciliopathies and dystroglycanopathies were the most common etiologies of congenital hydrocephalus in our cohort (19% and 26%, respectively). In 1 family with 4 affected members, we identified a homozygous truncating variant in EML1, which we propose as a novel cause of congenital hydrocephalus in addition to its suggested role in cortical malformation. Similarly, we show that recessive mutations in WDR81, previously linked to cerebellar ataxia, mental retardation, and disequilibrium syndrome 2, cause severe congenital hydrocephalus. Furthermore, we confirm the previously reported candidacy of MPDZ by presenting a phenotypic spectrum of congenital hydrocephalus associated with 5 recessive alleles.
Interpretation
Our study highlights the importance of recessive mutations in familial congenital hydrocephalus and expands the locus heterogeneity of this condition. Ann Neurol 2017;81:890–897
Intravascular intrauterine transfusion (IUT) is considered a safe procedure, but complications still occur, including fatalities.
Review the outcomes of Rh alloimmunization, including indications and ...possible complications.
Retrospective cohort (medical record review).
Tertiary care center.
We retrieved the records for all mothers who had an IUT for Rh alloimmunization between January 2009 and August 2019. We collected data on complications, post-transfusion hemoglobin and antibody combinations.
Complications of IUT.
119 mothers with 154 fetuses (154 different pregnancies).
The 154 fetuses had 560 intrauterine transfusions. The median pre-IUT hemoglobin was a median of 8.0 g/dL while the median post-IUT hemoglobin 16 g/dL. Immediate procedure-related complications included fetal bradycardia in 2.7%, significant bleeding from the cord puncture site (for more than 2 minutes in 0.9%), and contractions in 0.9%. Eight (5.2%) were delivered by cesarean delivery due to IUT-specific complications such as post-procedure fetal bradycardia. Intrauterine fetal death complicated 8.4% of the pregnancies (13 fetuses). Phototherapy was required in 76 (49.4%), postnatal blood transfusions in 17 (11%), and exchange transfusion in 11 (7.1%). Neonatal death occurred 8 (5.2%). Data were insufficient to assess associations of complications with antibody combinations.
Intrauterine transfusion is an effective treatment with high survival rates (around 90% for cases of Rh alloimmunization).
Case series.
None.
Establishing links between Mendelian phenotypes and genes enables the proper interpretation of variants therein. Autozygome, a rich source of homozygous variants, has been successfully utilized for ...the high throughput identification of novel autosomal recessive disease genes. Here, we highlight the utility of the autozygome for the high throughput confirmation of previously published tentative links to diseases.
Autozygome and exome analysis of patients with suspected Mendelian phenotypes. All variants were classified according to the American College of Medical Genetics and Genomics guidelines.
We highlight 30 published candidate genes (ACTL6B, ADAM22, AGTPBP1, APC, C12orf4, C3orf17 (NEPRO), CENPF, CNPY3, COL27A1, DMBX1, FUT8, GOLGA2, KIAA0556, LENG8, MCIDAS, MTMR9, MYH11, QRSL1, RUBCN, SLC25A42, SLC9A1, TBXT, TFG, THUMPD1, TRAF3IP2, UFC1, UFM1, WDR81, XRCC2, ZAK) in which we identified homozygous likely deleterious variants in patients with compatible phenotypes. We also identified homozygous likely deleterious variants in 18 published candidate genes (ABCA2, ARL6IP1, ATP8A2, CDK9, CNKSR1, DGAT1, DMXL2, GEMIN4, HCN2, HCRT, MYO9A, PARS2, PLOD3, PREPL, SCLT1, STX3, TXNRD2, WIPI2) although the associated phenotypes are sufficiently different from the original reports that they represent phenotypic expansion or potentially distinct allelic disorders.
Our results should facilitate the timely relabeling of these candidate disease genes in relevant databases to improve the yield of clinical genomic sequencing.
The purpose of this study is to describe recessive alleles in strictly dominant genes. Identifying recessive mutations in genes for which only dominant disease or risk alleles have been reported can ...expand our understanding of the medical relevance of these genes both phenotypically and mechanistically. The Saudi population is enriched for autozygosity, which enhances the homozygous occurrence of alleles, including pathogenic alleles in genes that have been associated only with a dominant inheritance pattern.
Exome sequencing of patients from consanguineous families with likely recessive phenotypes was performed. In one family, the genotype of the deceased children was inferred from their parents due to lack of available samples.
We describe the identification of 11 recessive variants (5 of which are reported here for the first time) in 11 genes for which only dominant disease or risk alleles have been reported. The observed phenotypes for these recessive variants were novel (e.g., FBN2-related myopathy and CSF1R-related brain malformation and osteopetrosis), typical (e.g., ACTG2-related visceral myopathy), or an apparently healthy state (e.g., PDE11A), consistent with the corresponding mouse knockout phenotypes.
Our results show that, in the era of genomic sequencing and "reverse phenotyping," recessive variants in dominant genes should not be dismissed based on perceived "incompatibility" with the patient's phenotype before careful consideration.Genet Med advance online publication 06 April 2017.
Leukodystrophies, genetic neurodevelopmental and/or neurodegenerative disorders of cerebral white matter, result from impaired myelin homeostasis and metabolism. Numerous genes have been implicated ...in these heterogeneous disorders; however, many individuals remain without a molecular diagnosis. Using whole-exome sequencing, biallelic variants in LSM7 were uncovered in two unrelated individuals, one with a leukodystrophy and the other who died in utero. LSM7 is part of the two principle LSM protein complexes in eukaryotes, namely LSM1-7 and LSM2-8. Here, we investigate the molecular and functional outcomes of these LSM7 biallelic variants in vitro and in vivo. Affinity purification-mass spectrometry of the LSM7 variants showed defects in the assembly of both LSM complexes. Lsm7 knockdown in zebrafish led to central nervous system defects, including impaired oligodendrocyte development and motor behavior. Our findings demonstrate that variants in LSM7 cause misassembly of the LSM complexes, impair neurodevelopment of the zebrafish, and may be implicated in human disease. The identification of more affected individuals is needed before the molecular mechanisms of mRNA decay and splicing regulation are added to the categories of biological dysfunctions implicated in leukodystrophies, neurodevelopmental and/or neurodegenerative diseases.
Derksen et al. use molecular and functional studies to demonstrate that variants in LSM7 lead to defects in the assembly of LSM complexes, impair neurodevelopment in zebrafish, and might be implicated in human disease.
Fetal abnormalities are detected in 3% of all pregnancies and are responsible for approximately 20% of all perinatal deaths. Chromosomal microarray analysis (CMA) and exome sequencing (ES) are widely ...used in prenatal settings for molecular genetic diagnostics with variable diagnostic yields. In this study, we aimed to determine the diagnostic yield of trio-ES in detecting the cause of fetal abnormalities within a highly consanguineous population. In families with a history of congenital anomalies, a total of 119 fetuses with structural anomalies were recruited and DNA from invasive samples were used together with parental DNA samples for trio-ES and CMA. Data were analysed to determine possible underlying genetic disorders associated with observed fetal phenotypes. The cohort had a known consanguinity of 81%. Trio-ES led to diagnostic molecular genetic findings in 59 fetuses (with pathogenic/likely pathogenic variants) most with multisystem or renal abnormalities. CMA detected chromosomal abnormalities compatible with the fetal phenotype in another 7 cases. Monogenic ciliopathy disorders with an autosomal recessive inheritance were the predominant cause of multisystem fetal anomalies (24/59 cases, 40.7%) with loss of function variants representing the vast majority of molecular genetic abnormalities. Heterozygous de novo pathogenic variants were found in four fetuses. A total of 23 novel variants predicted to be associated with the phenotype were detected. Prenatal trio-ES and CMA detected likely causative molecular genetic defects in a total of 55% of families with fetal anomalies confirming the diagnostic utility of trio-ES and CMA as first-line genetic test in the prenatal diagnosis of multisystem fetal anomalies including ciliopathy syndromes.
BACKGROUND:
Twin reversed arterial perfusion (TRAP) sequence is a rare condition that affects primarily monozygotic monochorionic twin pregnancies in which a normal twin acts as a pump (donor) for an ...acardiac recipient (perfuse) twin.
OBJECTIVE:
We report our experience over the last 13 years at a tertiary health care center.
DESIGN:
Descriptive, retrospective case series
SETTING:
Tertiary health care center
PATIENTS AND METHODS:
All TRAP cases managed between the years 2009 and 2022 at our Fetal Diagnosis and Therapy Center were included. Data recorded included demographic and clinical information which was used to generate descriptive data. Patients were managed by a multidisciplinary team with variable interventions.
MAIN OUTCOME MEASURE:
Survival of normal twin
SAMPLE SIZE:
Eight
RESULTS:
Eight pregnant women with TRAP syndrome were managed at our center during that period. One was monozygotic monochorionic and the others were monochorionic diamniotic. Median maternal age at presentation was 27 years and median gestational age at diagnosis was 23 weeks. All were diagnosed with ultrasound (US) imaging. Three were managed with bipolar ligation of the cord of the acardiac twin under general anesthesia, one US-guided (single port) and 2 fetoscopic (2 ports) with a median operative time of 39 minutes. The last five cases were managed with US-guided radiofrequency ablation (RFA) under local anesthesia, one needed 2 sessions, 1 week apart. The median duration of the RFA procedure was 23 minutes. There were no complications and all had viable normal babies born at a median of 32 weeks of gestation (6 C-section, 2 spontaneous membrane rupture).
CONCLUSIONS:
Acardiac twin cord ligation and RFA are feasible and safe options with excellent outcome for TRAP syndrome. RFA may be preferable owing to its less invasiveness under local anesthesia.
LIMITATIONS:
None, given the rarity of the disease and the study design.
CONFLICT OF INTEREST:
None.
Molecular autopsy refers to DNA-based identification of the cause of death. Despite recent attempts to broaden its scope, the term remains typically reserved to sudden unexplained death in young ...adults. In this study, we aim to showcase the utility of molecular autopsy in defining lethal variants in humans.
We describe our experience with a cohort of 481 cases in whom the cause of premature death was investigated using DNA from the index or relatives (molecular autopsy by proxy). Molecular autopsy tool was typically exome sequencing although some were investigated using targeted approaches in the earlier stages of the study; these include positional mapping, targeted gene sequencing, chromosomal microarray, and gene panels.
The study includes 449 cases from consanguineous families and 141 lacked family history (simplex). The age range was embryos to 18 years. A likely causal variant (pathogenic/likely pathogenic) was identified in 63.8% (307/481), a much higher yield compared to the general diagnostic yield (43%) from the same population. The predominance of recessive lethal alleles allowed us to implement molecular autopsy by proxy in 55 couples, and the yield was similarly high (63.6%). We also note the occurrence of biallelic lethal forms of typically non-lethal dominant disorders, sometimes representing a novel bona fide biallelic recessive disease trait. Forty-six disease genes with no OMIM phenotype were identified in the course of this study. The presented data support the candidacy of two other previously reported novel disease genes (FAAH2 and MSN). The focus on lethal phenotypes revealed many examples of interesting phenotypic expansion as well as remarkable variability in clinical presentation. Furthermore, important insights into population genetics and variant interpretation are highlighted based on the results.
Molecular autopsy, broadly defined, proved to be a helpful clinical approach that provides unique insights into lethal variants and the clinical annotation of the human genome.
Meckel-Gruber syndrome (MKS, OMIM #249000) is a multiple congenital malformation syndrome that represents the severe end of the ciliopathy phenotypic spectrum. Despite the relatively common ...occurrence of this syndrome among Arabs, little is known about its genetic architecture in this population. This is a series of 18 Arab families with MKS, who were evaluated clinically and studied using autozygome-guided mutation analysis and exome sequencing. We show that autozygome-guided candidate gene analysis identified the underlying mutation in the majority (n=12, 71%). Exome sequencing revealed a likely pathogenic mutation in three novel candidate MKS disease genes. These include C5orf42, Ellis-van-Creveld disease gene EVC2 and SEC8 (also known as EXOC4), which encodes an exocyst protein with an established role in ciliogenesis. This is the largest and most comprehensive genomic study on MKS in Arabs and the results, in addition to revealing genetic and allelic heterogeneity, suggest that previously reported disease genes and the novel candidates uncovered by this study account for the overwhelming majority of MKS patients in our population.
Understanding the impact of SARS-CoV-2 infection on pregnancy outcomes and of pregnancy on COVID-19 outcomes is critical for ensuring proper prenatal and antenatal care. No similar studies have been ...published in Saudi Arabia.
We performed a prospective cohort study of pregnant women with confirmed SARS-CoV-2 infection who presented at King Faisal Specialist Hospital and Research Center (KFSHRC) in Riyadh, Kingdom of Saudi Arabia. COVID-19 staging was performed, pregnancy-related complications were assessed, and neonatal infection was evaluated.
We enrolled 81 patients (mean age 31.75 years, SD 5.25) of which there were 17 cases in the first trimester, 20 in the second trimester, and 34 in the third trimester. The distribution of COVID-19 severity was 40 patients with Stage A, 36 with Stage B, 4 with Stage C, and 1 with Stage D. Complications were pregnancy loss in 2 patients (one in each first and second trimester) and 1 fetal death after 20 weeks of pregnancy, 7 patients with fetal growth restriction, and 8 with pre-term delivery.
We did not observe an unusual frequency of pregnancy-related complications due to SARS-CoV-2 infection in this high-risk obstetric population and there was no evidence of vertical transmission in newborns from women who delivered while positive for the virus.
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