Search

Objective: Mitochondrial complex‐I deficiency, nuclear type 16, is a rare autosomal recessive disorder caused by biallelic pathogenic variants in NDUFAF5 (C20orf7) (OMIM 618238). The aim of this study was to describe a severe early prenatal manifestation of this disorder, which was previously considered to occur only postnatally. Methods: This was a multicenter retrospective case series including five fetuses from three non‐related families, which shared common sonographic abnormalities, including brain cysts, corpus callosal malformations, non‐immune hydrops fetalis and growth restriction. Genetic evaluation included chromosomal microarray analysis and exome sequencing. Two fetuses from the same family were also available for pathology examination, including electron microscopy. Results: Chromosomal microarray analysis revealed no chromosomal abnormality in any of the tested cases. Trio exome sequencing demonstrated that three affected fetuses from three unrelated families were compound heterozygous or homozygous for likely pathogenic variants in NDUFAF5. No other causative variants were detected. The association between NDUFAF5 variants and fetal malformations was further confirmed by segregation analysis. Histological evaluation of fetal tissues and electron microscopy of the skeletal muscle, liver, proximal tubules and heart demonstrated changes that resembled postmortem findings in patients with mitochondrial depletion disorders as well as previously undescribed findings. Conclusions: Mitochondrial complex‐I deficiency and specifically biallelic mutations in NDUFAF5 have a role in abnormal fetal development, presenting with severe congenital malformations. Mitochondrial complex‐I disorders should be considered in the differential diagnosis of corpus callosal malformations and brain cysts, especially when associated with extracranial abnormalities, such as fetal growth restriction and non‐immune hydrops fetalis. © 2023 International Society of Ultrasound in Obstetrics and Gynecology. Linked article: There is a comment on this article by Finsterer. Click here to view the Correspondence. [ABSTRACT FROM AUTHOR]

Objectives: To determine the incremental diagnostic yield of exome sequencing (ES) after negative chromosomal microarray analysis (CMA) in cases of prenatally diagnosed agenesis of the corpus callosum (ACC) and to identify the associated genes and variants. Methods: A systematic search was performed to identify relevant studies published up until June 2022 using four databases: PubMed, SCOPUS, Web of Science and The Cochrane Library. Studies in English reporting on the diagnostic yield of ES following negative CMA in prenatally diagnosed partial or complete ACC were included. Authors of cohort studies were contacted for individual participant data and extended cohorts were provided for two of them. The increase in diagnostic yield with ES for pathogenic/likely pathogenic (P/LP) variants was assessed in all cases of ACC, isolated ACC, ACC with other cranial anomalies and ACC with extracranial anomalies. To identify all reported genetic variants, the systematic review included all ACC cases; however, for the meta‐analysis, only studies with ≥ three ACC cases were included. Meta‐analysis of proportions was employed using a random‐effects model. Quality assessment of the included studies was performed using modified Standards for Reporting of Diagnostic Accuracy criteria. Results: A total of 28 studies, encompassing 288 prenatally diagnosed ACC cases that underwent ES following negative CMA, met the inclusion criteria of the systematic review. We classified 116 genetic variants in 83 genes associated with prenatal ACC with a full phenotypic description. There were 15 studies, encompassing 268 cases, that reported on ≥ three ACC cases and were included in the meta‐analysis. Of all the included cases, 43% had a P/LP variant on ES. The highest yield was for ACC with extracranial anomalies (55% (95% CI, 35–73%)), followed by ACC with other cranial anomalies (43% (95% CI, 30–57%)) and isolated ACC (32% (95% CI, 18–51%)). Conclusions: ES demonstrated an incremental diagnostic yield in cases of prenatally diagnosed ACC following negative CMA. While the greatest diagnostic yield was observed in ACC with extracranial anomalies and ACC with other central nervous system anomalies, ES should also be considered in cases of isolated ACC. © 2023 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology. [ABSTRACT FROM AUTHOR]