For a long time, a comprehensive postmortem examination has been the most important investigation in unexplained fetal and neonatal deaths. In recent years, the usefulness of autopsy has been questioned due to the availability of improved prenatal imaging techniques and genome-wide sequencing that allow an early prenatal diagnosis of an increasing number of disorders. While concordance rates of prenatal ultrasound and postmortem findings are high, fetal autopsy may provide additional information in many cases and allow more accurate counseling of parents regarding the recurrence risk and management in future pregnancies. In this article, we provide a brief outline of a systematic fetal and placental evaluation by pathology and clinical genetics. Based on selected cases, the advantages of a comprehensive postmortem evaluation will be illustrated with emphasis on its role in quality control of prenatal ultrasound after termination of pregnancy, comprehensive and deep phenotyping, the interpretation of genetic variants and its high educational value.

Chromosomal mosaicism is a well-known phenomenon in prenatal cytogenetics and affects approximately 2 % of chorionic villus samples (CVS). The interpretation of mosaicism is challenging, and the major question is whether the abnormal cell line also affects the fetus (true fetal mosaicism, TFM). While mosaicism detected at CVS turns out to be confined to the placenta in the majority of cases, the individual risk of TFM widely varies and needs to be assessed on a case-by-case basis. This article aims to provide an overview on the different types of mosaicism in CVS, the probability of fetal involvement, the laboratory work-up, implications for genetic counselling, and potential effects upon placental function. It is emphasized that understanding placental mosaicism is crucial for the interpretation of results from non-invasive prenatal screening technologies, like NIPT for common aneuploidies, which are based on cell free placental DNA. Finally, we will discuss recent findings of genomic studies which indicate that placental mosaicism extends far beyond classic chromosome aberrations.

Dissecting biological pathways highlighted by Mendelian gene discovery has provided critical insights into the pathogenesis of Parkinson's disease (PD) and neurodegeneration. This approach ultimately catalyzes the identification of potential biomarkers and therapeutic targets. Here we identify PSMF1 as a gene implicated in parkinsonism and childhood neurodegeneration. We find that biallelic PSMF1 missense and loss-of-function variants co-segregate with phenotypes from early-onset PD to perinatal lethality with neurological manifestations across 18 pedigrees with 25 affected subjects, showing clear genotype-phenotype correlation. PSMF1 encodes the proteasome regulator PSMF1/hPI31, a highly conserved, ubiquitously expressed partner of the 20S proteasome and neurodegeneration-associated F-box-O 7 and valosin-containing proteins. We demonstrate that PSMF1 variants may affect proteasomal abundance and assembly, and are associated with alterations of mitochondrial membrane potential, respiration, dynamics and mitophagy in patient-derived fibroblasts. Furthermore, Drosophila and mouse models of PI31 loss of function exhibit age-dependent motor impairment, as well as brain-wide mitochondrial membrane depolarization and dopaminergic neurodegeneration in aged flies, and diffuse gliosis in mice. Collectively, our findings unequivocally link defective PSMF1/hPI31 to early-onset parkinsonism and neurodegeneration, and suggest proteasomal and mitochondrial dysfunction as pathogenic contributors.

Dissecting biological pathways highlighted by Mendelian gene discovery has provided critical insights into the pathogenesis of Parkinson's disease (PD) and neurodegeneration. This approach ultimately catalyzes the identification of potential biomarkers and therapeutic targets. Here, we identify PSMF1 as a novel gene implicated in parkinsonism and childhood neurodegeneration. We find that biallelic PSMF1 missense and loss-of-function variants co-segregate with phenotypes from early-onset PD to perinatal lethality with neurological manifestations across 17 pedigrees with 24 affected subjects, showing clear genotype-phenotype correlation. PSMF1 encodes the proteasome regulator PSMF1/PI31, a highly conserved, ubiquitously expressed partner of the 20S proteasome and neurodegeneration-associated F-box-O 7 and valosin-containing proteins. We demonstrate that PSMF1 variants impair mitochondrial membrane potential, dynamics and mitophagy, and may affect proteasomal abundance and assembly in patient-derived fibroblasts. Furthermore, Drosophila and mouse models of PSMF1 loss of function exhibit age-dependent motor impairment, as well as brain-wide mitochondrial membrane depolarization and dopaminergic neurodegeneration in aged flies, and diffuse gliosis in mice. Collectively, our findings unequivocally link defective PSMF1 to early-onset parkinsonism and neurodegeneration, and suggest proteasomal and mitochondrial dysfunction as mechanistic contributors.

IntroductionThe glycosylphosphatidylinositol (GPI) anchor is a glycolipid that anchors proteins to the eukaryotic cell surface. An anchoring process is a posttranslational modification of at least 150 molecules with various functions. Biallelic causal variants in the PIGQ gene (OMIM: * 605754) are associated with a type of disorder of glycosylphosphatidylinositol biosynthesis (PIGQ-congenital disorders of glycosylation (CDGs), also called multiple congenital anomalies-hypotonia-seizures syndrome 4 (MCAHS4, OMIM: # 618548). Only 11 patients with this condition have been reported to date.MethodsWe present two novel cases of MCAHS4 with one novel and one already known variant in the PIGQ gene, detailed phenotyping, and a review of all published cases so far. We used GestaltMatcher for deep gestalt analysis and investigated its potential use in diagnosing MCAHS4 patients.ResultsIn the PIGQ gene, we found one novel frameshift variant c.1092dupC, p.(Phe365LeufsTer78) and one missense c.1370T>G, p.(Leu457Arg) already listed in the ClinVar database as a variant of uncertain significance (VUS), whose pathogenicity we proved by a functional study on Chinese hamster ovarian cells. After reviewing all 13 already diagnosed MCAHS4 patients, we found that attacks of rhabdomyolysis induced by a febrile infection were documented only in our patient. Facial dysmorphism (coarse features, anteverted nares, and open mouth) seen in all analyzed MCAHS4 patients seems to be specific. Moreover, GestaltMatcher proved that MCAHS4 patients shared a similar facial phenotype.DiscussionThe present work expands the genotype spectrum by describing a novel causal PIGQ variant and validating the pathogenicity of an already-known VUS variant. Because of their life-threatening complications, attacks of rhabdomyolysis should be considered in MCAHS4 patients. GestaltMatcher can be an effective tool in the diagnostic setting of MCAHS4.

The Mediator complex regulates protein-coding gene transcription by coordinating the interaction of upstream enhancers with the basal transcription machinery at the promoter. Pathogenic variants in Mediator subunits typically lead to neurodevelopmental or neurodegenerative disorders with variable clinical presentations, designated as MEDopathies. Here, we report the identification of 25 individuals from 18 families with bi-allelic MED16 variants who have a multiple congenital anomalies (MCAs)-intellectual disability syndrome. Intellectual disability, speech delay, and/or motor delay of variable severity were constant and associated with variable combinations of craniofacial defects (micro/retrognathia, cleft palate, and preauricular tags), anomalies of the extremities, and heart defects (predominantly tetralogy of Fallot). Visual impairment, deafness, and magnetic resonance imaging (MRI) abnormalities were also frequent. The 26 variants identified were comprised of eight predicted protein-truncating (three intragenic deletions, two frameshifts, and one nonsense and two essential splice site variants) and 18 missense or in-frame duplication variants affecting conserved residues, without clear correlation between phenotypic severity and variant type combination. Three-dimensional modeling indicated that the missense and duplication variants likely have a destabilizing effect on the structural elements of the protein. Immunofluorescence assays demonstrated protein mislocalization from the nucleus to the cytoplasm for 16 of the 17 variants studied. Homozygous mutant med16 zebrafish presented growth delay and increased mortality compared with wild-type fish, and Med16 knockout mice are preweaning lethal, highlighting the conserved requirement of MED16 for development. Overall, we describe an autosomal recessive MCAs-intellectual disability MEDopathy, emphasizing the importance of Mediator during neurodevelopment and suggesting that some tissues are particularly sensitive to the loss of certain subunits.

Dear Editors, Neurofibromatosis type I (NF1) caused by pathogenic variants (PVs) in NF1, is a progressive condition characterized by multiple cafe-au-lait macules (CALMs), skinfold freckling, Lisch nodules, cutaneous, subcutaneous or plexiform neurofibromas, optic pathway glioma and distinctive osseous lesions, developing over time.1 According to the revised diagnostic criteria either at least two of the above mentioned clinical features or at least one clinical feature and the detection of a heterozygous NF1 PV are required in order to establish a diagnosis.2 Particularly in young children with multiple CALMs with/without skinfold freckling and no family history, the identification of an NF1 PV is frequently the only way to establish an early diagnosis and to distinguish NF1 from the clinically overlapping Legius syndrome, caused by SPRED1 PVs. The birth incidence of NF1 is 1/3,000, ∼50% being de novo cases.1 In a small subset of cases the PV arises postzygotically resulting in mosaic NF1 which is estimated to be 10–20 times rarer than constitutional NF1.3 In mosaics, severity and expression of the clinical phenotype depends on the affected tissues and the proportion of mutated cells. Early postzygotic PVs which involve tissues from different germ layers result in (mild) generalized NF1 and the PV is usually present also in the gametes (gono-somatic mosaicism).4 PVs occurring later in embryogenesis may result in purely somatic mosaicism presenting for example as neurofibromas and/or CALMs with a segmental distribution in NF1.3, 5 Because mosaicism frequently goes along with a milder phenotype,3, 5 some affected individuals may remain undiagnosed.6 This applies in particular to mosaicism for a PV which is restricted to gametes (gonadal or germline mosaicism) and, hence, does not lead to any clinical symptoms.4 Parental genetic mosaicism should always be taken into account when counselling parents of a child with “apparently” de novo NF1 as we illustrate with two families in which NF1 occurred in more than one child. Informed consent for publication was obtained for all individuals tested. Family 1: The index patient, a 2-year-old girl, presented with multiple CALMs and a facial plexiform neurofibroma. Genetic testing identified the NF1 PV NM_000267.3:c.1783_2001+205delins13, p.(Glu595Argfs*6). When her younger sister was clinically diagnosed with NF1 at the age of 2 years based on multiple CALMs, juvenile xanthogranulomas on the scalp and axillary freckling, the suspicion of mosaicism in one of the parents was raised. This was substantiated by identification of subtle bilateral inguinal freckling in the 37-year-old mother (Figure 1a, b). Using the sensitive method of locked nucleic acid analysis,7 we confirmed the presence of the NF1 PV in the daughter, at low percentages in blood (1.5%), left buccal swab (2.8%), urine (3.8%) and hair roots (2.9%) (Table 1) and, thus, gonado-somatic mosaicism in the mother. The mother developed at the age of 54 years an atypical neurofibroma in the left lower leg. Identification of the PV in this tumor also indicates Schwann cell involvement. Family 2: The female index patient presented with >15 CALMs at 7 months. NF1 was confirmed by identification of the recurrent NF1 PV NM_000267.3:c.910C>T, p.(Arg304Ter). Although NF1 clinical signs were absent in both parents, analysis of DNA from blood lymphocytes of both parents was requested. In neither of the two parents, Sanger sequencing revealed evidence for the presence of this NF1 PV. Due to the rare possibility of gonadal mosaicism, prenatal testing was offered to the parents on their inquiry in the next pregnancy, which unexpectedly detected the same NF1 PV in chorionic villi (Figure 2a). Gonadal mosaicism was retrospectively confirmed by Sanger sequencing detecting the PV in the sperm cells of the father (Figure 2b). The more sensitive digital droplet PCR revealed the mutated allele in 9% of sperm cells but not in blood, urine, buccal mucosa, and hair roots (Figure 2c, Table 1). Parents having a child with “apparently” de novo NF1 frequently raise worries of a recurrence risk in siblings. Case 1 illustrates the importance of a thorough dermatological and clinical examination of both parents followed by highly sensitive techniques to confirm low-level mosaicism in cases with suspected mosaicism in a parent. This strategy is superior to genetic testing of parental blood DNA for the PV with methods like Sanger sequencing, which due to limited sensitivity would not have detected the PV in the mosaic mother. Since freckling in the mother was restricted to one body part compatible with segmental NF1, case 1 as well as cases from the literature8 illustrate also the difficulties of predicting the transmission risk of the PV from the presentation of mosaicism in the patient. Only few cases of pure gonadal mosaicism have been reported in NF1.9-11 Nonetheless, as case 2 illustrates, parents should be made aware of this rare possibility to make an informed decision. Since the majority of point mutations are located on the paternal allele, analysis of sperm cells by Sanger sequencing, a method with limited sensitivity, may be informative as illustrated in case 2. Prenatal diagnosis should also be offered at the parents' request, as this is the only way to rule out the PV in subsequent pregnancies with certainty. We wish to thank the Austrian lay association NF Kinder (https://www.nfkinder.at/) for their continuous support of patients and their families with neurofibromatosis and of our work. None.

Coffin-Siris syndrome (CSS) is a rare genetic disorder and often co-occurs with attention-deficit hyperactivity disorder (ADHD) and autism spectrum (ASD). The present case study illustrates possible therapeutic interventions of these common psychiatric comorbidities taking into account the family interaction patterns. This can contribute to improve holistic management and overall level of functionality.

Pathogenic, largely truncating variants in the ETS2 repressor factor (ERF) gene, encoding a transcriptional regulator negatively controlling RAS-MAPK signaling, have been associated with syndromic craniosynostosis involving various cranial sutures and Chitayat syndrome, an ultrarare condition with respiratory distress, skeletal anomalies, and facial dysmorphism. Recently, a single patient with craniosynostosis and a phenotype resembling Noonan syndrome (NS), the most common disorder among the RASopathies, was reported to carry a de novo loss-of-function variant in ERF. Here, we clinically profile 26 individuals from 15 unrelated families carrying different germline heterozygous variants in ERF and showing a phenotype reminiscent of NS. The majority of subjects presented with a variable degree of global developmental and/or language delay. Their shared facial features included absolute/relative macrocephaly, high forehead, hypertelorism, palpebral ptosis, wide nasal bridge, and low-set/posteriorly angulated ears. Stature was below the 3rd centile in two-third of the individuals, while no subject showed typical NS cardiac involvement. Notably, craniosynostosis was documented only in three unrelated individuals, while a dolichocephalic aspect of the skull in absence of any other evidence supporting a premature closing of sutures was observed in other 10 subjects. Unilateral Wilms tumor was diagnosed in one individual. Most cases were familial, indicating an overall low impact on fitness. Variants were nonsense and frameshift changes, supporting ERF haploinsufficiency. These findings provide evidence that heterozygous loss-of-function variants in ERF cause a "RASopathy" resembling NS with or without craniosynostosis, and allow a first dissection of the molecular circuits contributing to MAPK signaling pleiotropy.

Congenital hyperinsulinemic hypoglycemia (HH) is the most frequent cause of persistent and recurrent hypoglycemia. Peripheral mononuclear blood cells (PBMCs) from a patient diagnosed with HH, alongside autism-spectrum-disorder (ASD), carrying a heterozygous c.812 T>A (L271H) mutation in the voltage-gated calcium channel subunit Cav1.3-encoding gene CACNA1D, were reprogrammed into induced pluripotent stem cells (iPSC). The CACNA1D L271H iPSC (IBKMOLi002-A) exhibit a normal karyotype, high expression of pluripotency-associated markers and the capacity to differentiate into cells of all three germ layers. We provide a novel patient-specific iPSC line, allowing to study HH, ASD, the associated neurodevelopmental disorder as well as CACNA1D-associated channelopathies in general.

•Congenital central hypoventilation syndrome combined with Hirschsprung disease is known as Haddad syndrome.•Mutations in the PHOX2B gene are causative.•Full diagnostic work-up of Haddad syndrome in a preterm infant is provided.

The RASopathies are a group of clinically and genetically heterogeneous developmental disorders caused by dysregulation of the RAS/MAPK signalling pathway. Variants in several components and regulators of this pathway have been identified as the pathogenetic cause. In 2015, missense variants in A2ML1 were reported in three unrelated families with clinical diagnosis of Noonan syndrome (NS) and a zebrafish model was presented showing heart and craniofacial defects similar to those caused by a NS-associated Shp2 variant. However, a causal role of A2ML1 variants in NS has not been confirmed since. Herein, we report on 15 individuals who underwent screening of RASopathy-associated genes and were found to carry rare variants in A2ML1, including variants previously proposed to be causative for NS. In cases where parental DNA was available, the respective A2ML1 variant was found to be inherited from an unaffected parent. Seven index patients carrying an A2ML1 variant presented with an alternate disease-causing genetic aberration. These findings underscore that current evidence is insufficient to support a causal relation between variants in A2ML1 and NS, questioning the inclusion of A2ML1 screening in diagnostic RASopathy testing.

Clinical characteristics of patients affected by neurofibromatosis type 1 carrying missense variants affecting p.Met1149, p.Arg1276, and p.Lys1423

: CLINICAL CHARACTERISTICS: FKBP14 kyphoscoliotic Ehlers-Danlos syndrome (FKBP14-kEDS) is characterized by congenital muscle hypotonia and weakness (typically improving during child-hood), progressive scoliosis, joint hypermobility, hyperelastic skin, gross motor developmental delay, myopathy, and hearing impairment. Most affected children achieve independent walking between ages two and four years. A decline of motor function in adulthood may be seen, but affected individuals are likely to be able to participate in activities of daily living in adulthood and maintain independent walking. Occasional features underlying systemic connective tissue involvement include aortic rupture and arterial dissection, subdural hygroma, insufficiency of cardiac valves, bluish sclerae, bladder diverticula, inguinal or umbilical herniae, and premature rupture of membranes during pregnancy. Rarer findings may include bifid uvula with submucous or frank cleft palate, speech/language delay without true cognitive impairment, and rectal prolapse. DIAGNOSIS/TESTING: Clinical diagnostic criteria rely on the finding of congenital muscular hypotonia AND congenital or early-onset kyphoscoliosis in addition to generalized joint hypermobility or further gene-specific and/or supportive clinical features. The diagnosis of FKBP14-kEDS is established in a proband by the identification of biallelic pathogenic variants in FKBP14 by molecular genetic testing. MANAGEMENT: Treatment of manifestations: In those with aortic dilation or vascular dissection, use of beta blockers may be considered; physical and occupational therapy to address age-dependent decline in muscular strength; standard treatment for severe scoliosis, clubbed foot, osteopenia/osteoporosis, refractive error, hearing impairment, and cleft palate. Surveillance: Blood pressure measurement at each visit; neurodevelopmental assessment at each visit until adolescence; evaluation by an orthopedic physician as clinically indicated but typically at least annually; periodic ophthalmology and hearing evaluations (e.g., every 2-3 years); DEXA scan, echocardiogram with consideration of cardiac MRI, and vascular ultrasonography every 2-5 years. Agents/circumstances to avoid: Sports that place stress on the joints; contact sports in those with an aortic aneurysm; hyperten-sion. Pregnancy management: An increased risk for miscarriage, premature rupture of membranes, and rupture of arteries in affected pregnant women should be considered. Delivery in a medical center with a high-risk perinatologist in attendance is recommended. GENETIC COUNSELING: FKBP14-kEDS is inherited in an autosomal recessive manner. Each sib of an affected individual has a 25% chance of being affected, a 50% chance of being an asymptomatic carrier, and a 25% chance of being unaffected and not a carrier. Carrier testing for at-risk relatives and prenatal testing for a pregnancy at increased risk are possible if both FKBP14 pathogenic variants have been identified in a family.