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In this review, we explore evidence that hypoxia in the developing human fetus can lead not only to the more commonly accepted disruptive-type defects, but also patterns of anomalies that suggest that hypoxia can exert a more classic teratogenic effect, using the brain as one example. We review neuropathology in the context of intrauterine hypoxia, particularly as it relates to carbon monoxide poisoning, in utero strokes, and homozygous alpha-thalassemia. In general, the associated brain injuries resemble those seen with other causes of hypoxic-ischemic injury. Fetal strokes during development usually lead to loss of brain tissue in areas that do not follow a typical embryologic pattern, and therefore are considered disruptions. However, there is also evidence that fetal brain ischemia can cause more classically recognized patterns of abnormal embryonic neuronal migration and organization such as polymicrogyria, cortical dysplasia, or dysgenesis, including select types of focal cortical dysplasia. This study summarizes available literature and evidence to raise clinicians' awareness regarding the association between hypoxia and congenital anomalies, including brain malformations., (© 2021 Wiley Periodicals LLC.)

Several recurrent malformation associations affecting the development of the embryo have been described in which a genetic etiology has not been found, including LBWC, MURCS, OAVS, OEIS, POC, VACTERL, referred to here as "recurrent constellations of embryonic malformations" (RCEM). All are characterized by an excess of reported monozygotic discordant twins and lack of familial recurrence. We performed a comprehensive review of published twin data across all six phenotypes to allow a more robust assessment of the association with twinning and potential embryologic timing of a disruptive event. We recorded the type of twinning, any overlapping features of another RCEM, maternal characteristics, and the use of ART. Statistically significant associations included an excess of monozygotic twins and 80% discordance rate for the phenotype across all twins. There was an 18.5% rate of ART and no consistently reported maternal adverse events during pregnancy. We found 24 instances of co-occurrence of two RCEM, suggesting a shared pathogenesis across all RCEM phenotypes. We hypothesize the following timing for RCEM phenotypes from the earliest perturbation in development to the latest: LBWC, POC, OEIS, VACTERL, OAVS, then MURCS. The RCEM group of conditions should be considered a spectrum that could be studied as a group., (© 2020 Wiley Periodicals LLC.)

Background: Kabuki syndrome (KS) is a clinically recognisable syndrome in which 70% of patients have a pathogenic variant in KMT2D or KDM6A . Understanding the function of these genes opens the door to targeted therapies. The purpose of this report is to propose diagnostic criteria for KS, particularly when molecular genetic testing is equivocal., Methods: An international group of experts created consensus diagnostic criteria for KS. Systematic PubMed searches returned 70 peer-reviewed publications in which at least one individual with molecularly confirmed KS was reported. The clinical features of individuals with known mutations were reviewed., Results: The authors propose that a definitive diagnosis can be made in an individual of any age with a history of infantile hypotonia, developmental delay and/or intellectual disability, and one or both of the following major criteria: (1) a pathogenic or likely pathogenic variant in KMT2D or KDM6A ; and (2) typical dysmorphic features (defined below) at some point of life. Typical dysmorphic features include long palpebral fissures with eversion of the lateral third of the lower eyelid and two or more of the following: (1) arched and broad eyebrows with the lateral third displaying notching or sparseness; (2) short columella with depressed nasal tip; (3) large, prominent or cupped ears; and (4) persistent fingertip pads. Further criteria for a probable and possible diagnosis, including a table of suggestive clinical features, are presented., Conclusion: As targeted therapies for KS are being developed, it is important to be able to make the correct diagnosis, either with or without molecular genetic confirmation., Competing Interests: Competing interests: The clinical and molecular genetic experts on Kabuki syndrome who collaborated on this manuscript were all participants of the Kabuki Syndrome Medical Advisory Board organised and sponsored by Takeda in January 2018. Although the meeting was facilitated and organised by Takeda, Takeda did not have any influence on the content of this report., (© Author(s) (or their employer(s)) 2019. No commercial re-use. See rights and permissions. Published by BMJ.)

Baratela-Scott syndrome (BSS) is a rare, autosomal-recessive disorder characterized by short stature, facial dysmorphisms, developmental delay, and skeletal dysplasia caused by pathogenic variants in XYLT1. We report clinical and molecular investigation of 10 families (12 individuals) with BSS. Standard sequencing methods identified biallelic pathogenic variants in XYLT1 in only two families. Of the remaining cohort, two probands had no variants and six probands had only a single variant, including four with a heterozygous 3.1 Mb 16p13 deletion encompassing XYLT1 and two with a heterozygous truncating variant. Bisulfite sequencing revealed aberrant hypermethylation in exon 1 of XYLT1, always in trans with the sequence variant or deletion when present; both alleles were methylated in those with no identified variant. Expression of the methylated XYLT1 allele was severely reduced in fibroblasts from two probands. Southern blot studies combined with repeat expansion analysis of genome sequence data showed that the hypermethylation is associated with expansion of a GGC repeat in the XYLT1 promoter region that is not present in the reference genome, confirming that BSS is a trinucleotide repeat expansion disorder. The hypermethylated allele accounts for 50% of disease alleles in our cohort and is not present in 130 control subjects. Our study highlights the importance of investigating non-sequence-based alterations, including epigenetic changes, to identify the missing heritability in genetic disorders., (Copyright © 2018 American Society of Human Genetics. Published by Elsevier Inc. All rights reserved.)

Gomez-Lopez-Hernandez syndrome (GLHS) is a rare neurocutaneous disorder. We are aware of thirty previously reported cases. We present four additional patients with this condition. Previously reported patients have shown the hallmark triad of rhombocephalosynapsis, trigeminal anesthesia, and bilateral parietal or parieto-occipital alopecia. Rhombencephalosynapsis consists of agenesis of the cerebellar vermis, fusion of the cerebellar hemispheres, and the dentate nuclei. The gene or genes responsible for GLHS remain unknown. Alopecia is seen in all previously reported cases of GLHS. Additional craniofacial findings such as low-set and posteriorly rotated ears, midface retrusion, craniosynostosis, and brachyturricephaly are also very common in this syndrome. Trigeminal anesthesia, reported in the original three patients, is seen in just over half of reported patients. Most patients with GLHS have motor delays, intellectual disability, and hypotonia. Unusual stereotypic movements of the head are seen in many patients with GLHS. Neuroimaging of patients with GLHS shows rhombencephalosynapsis is universally present, with ventriculomegaly/hydrocephalus and cerebellar hypoplasia being common. We propose that rhombencephalosynapsis and scalp alopecia are necessary, but by themselves not sufficient, for a diagnosis of GLHS. Additional findings of trigeminal anesthesia or one of two major craniofacial findings (brachycephaly and/or turricephaly or midface retrusion) are sufficient to make a diagnosis of GLHS. Additional categories of probable and possible GLHS are proposed for patients whose examination may be compatible with a diagnosis of GLHS, but CNS imaging has not yet been obtained. © 2013 Wiley Periodicals, Inc., (Copyright © 2013 Wiley Periodicals, Inc.)

Rhombencephalosynapsis (RES) is an uncommon cerebellar malformation characterized by fusion of the hemispheres without an intervening vermis. Frequently described in association with Gómez-López-Hernández syndrome, RES also occurs in conjunction with VACTERL features and with holoprosencephaly (HPE). We sought to determine the full phenotypic spectrum of RES in a large cohort of patients. Information was obtained through database review, patient questionnaire, radiographic, and morphologic assessment, and statistical analysis. We assessed 53 patients. Thirty-three had alopecia, 3 had trigeminal anesthesia, 14 had VACTERL features, and 2 had HPE with aventriculy. Specific craniofacial features were seen throughout the cohort, but were more common in patients with alopecia. We noted substantial overlap between groups. We conclude that although some distinct subgroups can be delineated, the overlapping features seen in our cohort suggest an underlying spectrum of RES-associated malformations rather than a collection of discrete syndromes., (Copyright © 2012 Wiley Periodicals, Inc.)

Rhombencephalosynapsis is a midline brain malformation characterized by missing cerebellar vermis with apparent fusion of the cerebellar hemispheres. Rhombencephalosynapsis can be seen in isolation or together with other central nervous system and extra-central nervous system malformations. Gómez-López-Hernández syndrome combines rhombencephalosynapsis with parietal/temporal alopecia and sometimes trigeminal anaesthesia, towering skull shape and dysmorphic features. Rhombencephalosynapsis can also be seen in patients with features of vertebral anomalies, anal atresia, cardiovascular anomalies, trachea-oesophageal fistula, renal anomalies, limb defects (VACTERL) association. Based on a comprehensive evaluation of neuroimaging findings in 42 patients with rhombencephalosynapsis, we propose a spectrum of severity, ranging from mild (the partial absence of nodulus, anterior and posterior vermis), to moderate (the absence of posterior vermis with some anterior vermis and nodulus present), to severe (the absence of posterior and anterior vermis with some nodulus present), to complete (the absence of the entire vermis including nodulus). We demonstrate that the severity of rhombencephalosynapsis correlates with fusion of the tonsils, as well as midbrain abnormalities including aqueductal stenosis and midline fusion of the tectum. Rhombencephalosynapsis is also associated with multiple forebrain abnormalities including absent olfactory bulbs, dysgenesis of the corpus callosum, absent septum pellucidum and, in rare patients, atypical forms of holoprosencephaly. The frequent association between rhombencephalosynapsis and aqueductal stenosis prompted us to evaluate brain magnetic resonance images in other patients with aqueductal stenosis at our institution, and remarkably, we identified rhombencephalosynapsis in 9%. Strikingly, subjects with more severe rhombencephalosynapsis have more severely abnormal neurodevelopmental outcome, as do subjects with holoprosencephaly and patients with VACTERL features. In summary, our data provide improved diagnostic and prognostic information, and support disruption of dorsal-ventral patterning as a mechanism underlying rhombencephalosynapsis.

Background: The 9q subtelomeric deletion syndrome (9qSTDS) is clinically characterised by moderate to severe mental retardation, childhood hypotonia and facial dysmorphisms. In addition, congenital heart defects, urogenital defects, epilepsy and behavioural problems are frequently observed. The syndrome can be either caused by a submicroscopic 9q34.3 deletion or by intragenic EHMT1 mutations leading to haploinsufficiency of the EHMT1 gene. So far it has not been established if and to what extent other genes in the 9q34.3 region contribute to the phenotype observed in deletion cases. This study reports the largest cohort of 9qSTDS cases so far., Methods and Results: By a multiplex ligation dependent probe amplification (MLPA) approach, the authors identified and characterised 16 novel submicroscopic 9q deletions. Direct sequence analysis of the EHMT1 gene in 24 patients exhibiting the 9qSTD phenotype without such deletion identified six patients with an intragenic EHMT1 mutation. Five of these mutations predict a premature termination codon whereas one mutation gives rise to an amino acid substitution in a conserved domain of the protein., Conclusions: The data do not provide any evidence for phenotype-genotype correlations between size of the deletions or type of mutations and severity of clinical features. Therefore, the authors confirm the EHMT1 gene to be the major determinant of the 9qSTDS phenotype. Interestingly, five of six patients who had reached adulthood had developed severe psychiatric pathology, which may indicate that EHMT1 haploinsufficiency is associated with neurodegeneration in addition to neurodevelopmental defect.

Background: Diabetes is the most common endocrinologic complication during pregnancy, and poor control can lead to a variety of congenital anomalies in the fetus. However, it is often difficult to differentiate between diabetes-related anomalies and an underlying genetic syndrome. In the 1990s it was proposed that preaxial hallucal polydactyly, particularly when proximally placed, was a distinguishing feature of diabetic embryopathy., Methods: We summarize the clinical findings in 18 patients (five previously reported in abstract form) with diabetic embryopathy and preaxial hallucal polydactyly to determine which features are most suggestive of diabetic embryopathy., Results: All 18 patients had preaxial hallucal polydactyly (seven bilateral, 11 unilateral), of which 15 patients had proximal implantation of the extra hallux. Further skeletal findings included the following: segmentation anomalies of the spine, equinovarus deformity of the feet, tibial hemimelia, hip dysplasia, and femoral hypoplasia. Upper limb malformations were rare. Eleven of the 18 mothers had prepregnancy insulin-dependent diabetes, while one mother had prepregnancy type 2 diabetes that required insulin therapy in the 3(rd) trimester. Five mothers had gestational diabetes that required insulin and one mother had gestational diabetes that was controlled by diet. The majority of mothers had poorly controlled diabetes during the pregnancy., Conclusions: Proximally placed preaxial hallucal polydactyly, particularly when coupled with segmentation anomalies of the spine and tibial hemimelia, is highly suggestive of diabetic embryopathy. Varying degrees of diabetes in the mothers point to a possible genetic predisposition interacting with the teratogenic effects of poor glycemic control leading to specific limb anomalies.

Mowat-Wilson syndrome (MWS) is a relatively newly described multiple congenital anomaly/mental retardation syndrome. Haploinsufficiency of a gene termed ZFHX1B (also known as SIP1) on chromosome 2 is responsible for this condition, and clinical genetic testing for MWS recently became available. The majority of reports in the literature originate from Northern Europe and Australia. Here we report our clinical experience with 12 patients diagnosed with MWS within a 2-year period of time in the United States, with particular emphasis on clinical characteristics and management strategies. Individuals with this condition have characteristic facial features, including microcephaly, hypertelorism, medially flared and broad eyebrows, prominent columella, pointed chin, and uplifted earlobes, which typically prompt the clinician to consider the diagnosis. Medical issues in our cohort of patients included seizures (75%) with no predeliction for any particular seizure type; agenesis of the corpus callosum (60% of our patients studied); congenital heart defects (75%), particularly involving the pulmonary arteries and/or valves; hypospadias (55% of males); severely impaired or absent speech (100% of individuals over 1 year of age) with relatively spared receptive language; and Hirschsprung disease (50%) or chronic constipation (25%). The incidence of MWS is unknown, but based on the number of patients identified in a short period of time within the US, it is likely greatly under recognized. MWS should be considered in any individual with severely impaired or absent speech, especially in the presence of seizures and anomalies involving the pulmonary arteries (particularly pulmonary artery sling) or pulmonary valves., ((c) 2006 Wiley-Liss, Inc.)

The Marshall-Smith syndrome (MSS) is a distinct malformation syndrome characterized by accelerated skeletal maturation, relative failure to thrive, respiratory difficulties, mental retardation, and unusual facies, including prominent forehead, shallow orbits, blue sclerae, depressed nasal bridge, and micrognathia. At least 33 cases have been reported in the literature, mostly as single case reports or small series. The purpose of the present study is to report on the clinical findings and natural history of MSS in five children and to review the features of three others previously reported, with particular attention to the skeletal and connective tissue findings. Our study demonstrates an increased rate of nontraumatic fractures and other bony and connective tissue abnormalities that support the hypothesis that MSS should be considered an osteochondrodysplasia. In addition, long-term survival beyond infancy is possible if respiratory problems are expectantly and aggressively managed., ((c) 2005 Wiley-Liss, Inc.)

Kabuki syndrome (KS) (Kabuki make-up syndrome, Niikawa-Kuroki syndrome) is a multiple malformation/mental retardation syndrome that was described initially in Japan but is now known to occur in many other ethnic groups. It is characterized by distinctive facial features (eversion of the lower lateral eyelid, arched eyebrows with the lateral one-third dispersed or sparse, depressed nasal tip, and prominent ears), skeletal anomalies, dermatoglyphic abnormalities, short stature, and mental retardation. A number of other manifestations involving other organ systems can aid in the diagnosis and management of KS. This review will focus on the diagnostic criteria, the common and rare features of KS by organ system, and the possible etiology of this interesting condition.

Methotrexate, a methyl derivative of aminopterin, is a folic acid antagonist and a known human teratogen; misoprostol is a synthetic prostaglandin E1 analog that causes uterine contractions. Recently, there has been resurgence in the use of methotrexate in combination with misoprostol or of methotrexate alone for the treatment of unwanted or ectopic pregnancies, respectively. This report documents the findings in four infants who were exposed prenatally to methotrexate alone or in combination with misoprostol in a failed attempt at medical abortion or treatment of ectopic pregnancy. All patients demonstrated growth deficiency, with growth parameters <10th centile, and all displayed features consistent with methotrexate and/or misoprostol embryopathy. Since an increasing number of medical abortions are being performed, it is important for physicians to recognize the associated teratogenic effects of these abortifacients. Data from the patients herein described should prompt obstetricians and other health care practitioners who prescribe these medications to counsel their patients regarding these risks, especially if the treatment regimen fails to induce an abortion., (Copyright 2003 Wiley-Liss, Inc.)