Auditory Neuropathy Spectrum Disorder Progressing with Motor and Sensory Neuropathy Caused by an ATP1A1 Variant

We encountered a 27-year-old Japanese woman with sensorineural deafness progressing to motor and sensory neuropathy. At 16 years old, she had developed weakness in her lower extremities and hearing impairment, which gradually deteriorated. At 22 years old, combined audiological, electrophysiological, and radiological examination results were consistent with auditory neuropathy spectrum disorder (ANSD). Genetic analyses identified a previously reported missense variant in the ATP1A1 gene (NM_000701.8:c.1799C>G, p.Pro600Arg). Although sensorineural deafness has been reported as a clinical manifestation of ATP1A1-related disorders, our case suggested that ANSD may underlie the pathogenesis of deafness in ATP1A1-related disorders. This case report broadens the genotype-phenotype spectrum of ATP1A1-related disorders.

Spliceosome malfunction causes neurodevelopmental disorders with overlapping features

Pre-mRNA splicing is a highly coordinated process. While its dysregulation has been linked to neurological deficits, our understanding of the underlying molecular and cellular mechanisms remains limited. We implicated pathogenic variants in U2AF2 and PRPF19, encoding spliceosome subunits in neurodevelopmental disorders (NDDs), by identifying 46 unrelated individuals with 23 de novo U2AF2 missense variants (including 7 recurrent variants in 30 individuals) and 6 individuals with de novo PRPF19 variants. Eight U2AF2 variants dysregulated splicing of a model substrate. Neuritogenesis was reduced in human neurons differentiated from human pluripotent stem cells carrying two U2AF2 hyper-recurrent variants. Neural loss of function (LoF) of the Drosophila orthologs U2af50 and Prp19 led to lethality, abnormal mushroom body (MB) patterning, and social deficits, which were differentially rescued by wild-type and mutant U2AF2 or PRPF19. Transcriptome profiling revealed splicing substrates or effectors (including Rbfox1, a third splicing factor), which rescued MB defects in U2af50-deficient flies. Upon reanalysis of negative clinical exomes followed by data sharing, we further identified 6 patients with NDD who carried RBFOX1 missense variants which, by in vitro testing, showed LoF. Our study implicates 3 splicing factors as NDD-causative genes and establishes a genetic network with hierarchy underlying human brain development and function.

Biallelic structural variations within FGF12 detected by long-read sequencing in epilepsy

We discovered biallelic intragenic structural variations (SVs) in FGF12 by applying long-read whole genome sequencing to an exome-negative patient with developmental and epileptic encephalopathy (DEE). We also found another DEE patient carrying a biallelic (homozygous) single-nucleotide variant (SNV) in FGF12 that was detected by exome sequencing. FGF12 heterozygous recurrent missense variants with gain-of-function or heterozygous entire duplication of FGF12 are known causes of epilepsy, but biallelic SNVs/SVs have never been described. FGF12 encodes intracellular proteins interacting with the C-terminal domain of the alpha subunit of voltage-gated sodium channels 1.2, 1.5, and 1.6, promoting excitability by delaying fast inactivation of the channels. To validate the molecular pathomechanisms of these biallelic FGF12 SVs/SNV, highly sensitive gene expression analyses using lymphoblastoid cells from the patient with biallelic SVs, structural considerations, and Drosophila in vivo functional analysis of the SNV were performed, confirming loss-of-function. Our study highlights the importance of small SVs in Mendelian disorders, which may be overlooked by exome sequencing but can be detected efficiently by long-read whole genome sequencing, providing new insights into the pathomechanisms of human diseases.

A missense variant at the RAC1-PAK1 binding site of RAC1 inactivates downstream signaling in VACTERL association

RAC1 at 7p22.1 encodes a RAC family small GTPase that regulates actin cytoskeleton organization and intracellular signaling pathways. Pathogenic RAC1 variants result in developmental delay and multiple anomalies. Here, exome sequencing identified a rare de novo RAC1 variant [NM_018890.4:c.118T > C p.(Tyr40His)] in a male patient. Fetal ultrasonography indicated the patient to have multiple anomalies, including persistent left superior vena cava, total anomalous pulmonary venous return, esophageal atresia, scoliosis, and right-hand polydactyly. After birth, craniofacial dysmorphism and esophagobronchial fistula were confirmed and VACTERL association was suspected. One day after birth, the patient died of respiratory failure caused by tracheal aplasia type III. The molecular mechanisms of pathogenic RAC1 variants remain largely unclear; therefore, we biochemically examined the pathophysiological significance of RAC1-p.Tyr40His by focusing on the best characterized downstream effector of RAC1, PAK1, which activates Hedgehog signaling. RAC1-p.Tyr40His interacted minimally with PAK1, and did not enable PAK1 activation. Variants in the RAC1 Switch II region consistently activate downstream signals, whereas the p.Tyr40His variant at the RAC1-PAK1 binding site and adjacent to the Switch I region may deactivate the signals. It is important to accumulate data from individuals with different RAC1 variants to gain a full understanding of their varied clinical presentations.

Imagawa-Matsumoto syndrome: SUZ12-related overgrowth disorder

The SUZ12 gene encodes a subunit of polycomb repressive complex 2 (PRC2) that is essential for development by silencing the expression of multiple genes. Germline heterozygous variants in SUZ12 have been found in Imagawa-Matsumoto syndrome (IMMAS) characterized by overgrowth and multiple dysmorphic features. Similarly, both EZH2 and EED also encode a subunit of PRC2 each and their pathogenic variants cause Weaver syndrome and Cohen-Gibson syndrome, respectively. Clinical manifestations of these syndromes significantly overlap, although their different prevalence rates have recently been noted: generalized overgrowth, intellectual disability, scoliosis, and excessive loose skin appear to be less prevalent in IMMAS than in the other two syndromes. We could not determine any apparent genotype-phenotype correlation in IMMAS. The phenotype of neurofibromatosis type 1 arising from NF1 deletion was also shown to be modified by the deletion of SUZ12, 560 kb away. This review deepens our understanding of the clinical and genetic characteristics of IMMAS together with other overgrowth syndromes related to PRC2. We also report on a novel IMMAS patient carrying a splicing variant (c.1023+1G>C) in SUZ12. This patient had a milder phenotype than other previously reported IMMAS cases, with no macrocephaly or overgrowth phenotypes, highlighting the clinical variation in IMMAS.

Cervical Cerclage to Prevent Intrauterine Balloon Prolapse

Intrauterine balloon prolapse sometimes occurs, and the intrauterine balloon must be reinserted. Furthermore, intrauterine balloon tamponade (IBT) failure can necessitate additional invasive procedures. We report a case of cervical cerclage with IBT for placenta previa with a cervical dilation. In our case, emergency cesarean section was performed at 35 + 4 weeks of gestation because of persistent hemorrhage. During the operation, we performed IBT to prevent further postpartum hemorrhage. However, immediately after the operation, uterine cervical dilatation was 6 cm, which resulted in cervical dilation and prolapse of the intrauterine balloon. Therefore, we performed cervical cerclage using absorbable sutures with IBT and blood transfusion. We speculated that the intrauterine balloon might have induced cervical canal ripening during the operation. Our case suggested that cervical cerclage with IBT is a useful method to prevent intrauterine balloon prolapse in cases with cervical dilation.

Distal 2q duplication in a patient with intellectual disability

We report on a patient with a distal 16.4-Mb duplication at 2q36.3-qter, who presented with severe intellectual disability, microcephaly, brachycephaly, prominent forehead, hypertelorism, prominent eyes, thin upper lip, and progenia. Copy number analysis using whole exome data detected a distal 2q duplication. This is the first report describing a distal 2q duplication at the molecular level.

Two families with TET3-related disorder showing neurodevelopmental delay with craniofacial dysmorphisms

TET3 at 2p13.1 encodes tet methylcytosine dioxygenase 3, a demethylation enzyme that converts 5-methylcytosine to 5-hydroxymethylcytosine. Beck et al. reported that patients with TET3 abnormalities in either an autosomal dominant or recessive inheritance fashion clinically showed global developmental delay, intellectual disability, and dysmorphisms. In this study, exome sequencing identified both mono- and biallelic TET3 variants in two families: a de novo variant NM_001287491.1:c.3028 A > G:p.(Asn1010Asp), and compound heterozygous variants NM_001287491.1:c.[2077 C > T];[2896 T > G],p.[Gln693*];[Cys966Gly]. Despite the different inheritance modes, the affected individuals showed similar phenotypic features. Including these three patients, only 14 affected individuals have been reported to date. The accumulation of data regarding individuals with TET3-related disorder is necessary to describe their clinical spectrum.

Laparoscopic Removal of Modified Vertical Uterine Compression Sutures due to Postoperative Focal Pain

Previously we reported laparoscopic removal of compression sutures due to uterine ischemia and related pain, which has two of the difficult aspects: (1) maneuvering the curved needle to perform compression suturing in the narrow surgical field, and (2) distinguishing between the threads of the cesarean section wound sutures versus the vertical compression sutures during removal, as the threads are the same white color. We performed vertical compression sutures for intrapartum hemorrhage with total placental previa, and modified both the needle type and the color of the thread used for uterine compression sutures during cesarean section. After the operation, we performed successful laparoscopic removal of compression sutures for postoperative focal pain. Changing the needle type and color helped to perform operations. The present case supports the concept that the laparoscopic removal of uterine compression suturing is useful for controlling pain in cases where general analgesics are ineffective.

Retrospective study of the recurrence risk of preterm birth in Japan

Background: A history of preterm birth is a risk factor for preterm birth in a future pregnancy, and there are some reports of prevention methods, such as the administration of progesterone. However, the rate of recurrence of preterm birth in Japan has not been clarified, and there is no data for judging whether these preventive methods are effective.Objective: To clarify the risk of recurrence of preterm birth and preterm prelabor rupture of membranes (pPROM) in Japan.Materials and methods: A retrospective study was conducted using the perinatal registration database of the Japan Obstetrics and Gynecology Society for the Perinatal Center from 2014 to 2016. There were 704,418 subjects, of which 190,990 were excluded those with unknown maternal information, those under the age of 20 years, those with perinatal disease related to preterm birth, and first-time mothers.Results: Logistic model unavailable and multivariate analysis were performed. An analysis of the preterm birth history indicated the risk of preterm birth in the current pregnancy, and the odds ratio for preterm birth recurrence once, twice, and three times or more was 3.3, 6.6, and 7.8, respectively. As a secondary analysis, we analyzed whether the history of pPROM is a risk factor of recurrence of pPROM and found a significant association with an odds ratio of 3.4.Conclusion: Having a preterm birth history increases the risk of recurrence of preterm birth, and the risk of recurrent preterm birth increases as the number of preterm births increases. Although this report is intended for high-risk pregnancies wherein the rate of preterm birth is high, as previously reported, our data indicate that in Japan, preterm birth is a risk factor of recurrent preterm birth.