Diagnosis and management in Rubinstein-Taybi syndrome: first international consensus statement.

Rubinstein-Taybi syndrome (RTS) is an archetypical genetic syndrome that is characterised by intellectual disability, well-defined facial features, distal limb anomalies and atypical growth, among numerous other signs and symptoms. It is caused by variants in either of two genes (CREBBP, EP300) which encode for the proteins CBP and p300, which both have a function in transcription regulation and histone acetylation. As a group of international experts and national support groups dedicated to the syndrome, we realised that marked heterogeneity currently exists in clinical and molecular diagnostic approaches and care practices in various parts of the world. Here, we outline a series of recommendations that document the consensus of a group of international experts on clinical diagnostic criteria for types of RTS (RTS1: CREBBP; RTS2: EP300), molecular investigations, long-term management of various particular physical and behavioural issues and care planning. The recommendations as presented here will need to be evaluated for improvements to allow for continued optimisation of diagnostics and care.

Delineation of the adult phenotype of Coffin-Siris syndrome in 35 individuals.

Coffin-Siris syndrome (CSS) is a rare multisystemic autosomal dominant disorder. Since 2012, alterations in genes of the SWI/SNF complex were identified as the molecular basis of CSS, studying largely pediatric cohorts. Therefore, there is a lack of information on the phenotype in adulthood, particularly on the clinical outcome in adulthood and associated risks. In an international collaborative effort, data from 35 individuals ≥ 18 years with a molecularly ascertained CSS diagnosis (variants in ARID1B, ARID2, SMARCA4, SMARCB1, SMARCC2, SMARCE1, SOX11, BICRA) using a comprehensive questionnaire was collected. Our results indicate that overweight and obesity are frequent in adults with CSS. Visual impairment, scoliosis, and behavioral anomalies are more prevalent than in published pediatric or mixed cohorts. Cognitive outcomes range from profound intellectual disability (ID) to low normal IQ, with most individuals having moderate ID. The present study describes the first exclusively adult cohort of CSS individuals. We were able to delineate some features of CSS that develop over time and have therefore been underrepresented in previously reported largely pediatric cohorts, and provide recommendations for follow-up.

Validation of clinical exome sequencing in the diagnostic procedure of patients with intellectual disability in clinical practice.

Intellectual disability (ID) has a prevalence of 1-3% and aproximately 30-50% of ID cases have a genetic cause. Development of next-generation sequencing has shown a high diagnostic potential. The aim of this work was to evaluate the diagnostic yield of clinical exome sequencing in 188 ID patients and the economic impact of its introduction in clinical practice. An analysis of diagnostic yield according to the different clinical variables was performed in order to establish an efficient diagnostic protocol for ID patients. Diagnostic yield of clinical exome sequencing was significant (34%) supporting its utility in diagnosis of ID patients. Wide genetic heterogeneity and predominance of autosomal dominant de novo variants in ID patients were observed. Time to diagnosis was shortened and diagnostic study costs decreased by 62% after implementation of clinical exome sequencing. No association was found between any of the variables analyzed and a higher diagnostic yield; added to the fact that many of the diagnoses weren't clinically detectable, the reduction of time to diagnosis and the economic savings with respect to classical diagnostic studies, strengthen the clinical and economical convenience of early implementation of clinical exome sequencing in the diagnostic workup of ID patients in clinical practice.

CERT1 mutations perturb human development by disrupting sphingolipid homeostasis.

Neural differentiation, synaptic transmission, and action potential propagation depend on membrane sphingolipids, whose metabolism is tightly regulated. Mutations in the ceramide transporter CERT (CERT1), which is involved in sphingolipid biosynthesis, are associated with intellectual disability, but the pathogenic mechanism remains obscure. Here, we characterize 31 individuals with de novo missense variants in CERT1. Several variants fall into a previously uncharacterized dimeric helical domain that enables CERT homeostatic inactivation, without which sphingolipid production goes unchecked. The clinical severity reflects the degree to which CERT autoregulation is disrupted, and inhibiting CERT pharmacologically corrects morphological and motor abnormalities in a Drosophila model of the disease, which we call ceramide transporter (CerTra) syndrome. These findings uncover a central role for CERT autoregulation in the control of sphingolipid biosynthetic flux, provide unexpected insight into the structural organization of CERT, and suggest a possible therapeutic approach for patients with CerTra syndrome.

The neurodevelopmental and facial phenotype in individuals with a TRIP12 variant.

Haploinsufficiency of TRIP12 causes a neurodevelopmental disorder characterized by intellectual disability associated with epilepsy, autism spectrum disorder and dysmorphic features, also named Clark-Baraitser syndrome. Only a limited number of cases have been reported to date. We aimed to further delineate the TRIP12-associated phenotype and objectify characteristic facial traits through GestaltMatcher image analysis based on deep-learning algorithms in order to establish a TRIP12 gestalt. 38 individuals between 3 and 66 years (F = 20, M = 18) - 1 previously published and 37 novel individuals - were recruited through an ERN ITHACA call for collaboration. 35 TRIP12 variants were identified, including frameshift (n = 15) and nonsense (n = 6) variants, as well as missense (n = 5) and splice (n = 3) variants, intragenic deletions (n = 4) and two multigene deletions disrupting TRIP12. Though variable in severity, global developmental delay was noted in all individuals, with language deficit most pronounced. About half showed autistic features and susceptibility to obesity seemed inherent to this disorder. A more severe expression was noted in individuals with a missense variant. Facial analysis showed a clear gestalt including deep-set eyes with narrow palpebral fissures and fullness of the upper eyelids, downturned corners of the mouth and large, often low-set ears with prominent earlobes. We report the largest cohort to date of individuals with TRIP12 variants, further delineating the associated phenotype and introducing a facial gestalt. These findings will improve future counseling and patient guidance.

PHIP-associated Chung-Jansen syndrome: Report of 23 new individuals.

In 2016 and 2018, Chung, Jansen and others described a new syndrome caused by haploinsufficiency of PHIP (pleckstrin homology domain interacting protein, OMIM *612,870) and mainly characterized by developmental delay (DD), learning difficulties/intellectual disability (ID), behavioral abnormalities, facial dysmorphism and obesity (CHUJANS, OMIM #617991). So far, PHIP alterations appear to be a rare cause of DD/ID. "Omics" technologies such as exome sequencing or array analyses have led to the identification of distinct types of alterations of PHIP, including, truncating variants, missense substitutions, splice variants and large deletions encompassing portions of the gene or the entire gene as well as adjacent genomic regions. We collected clinical and genetic data of 23 individuals with PHIP-associated Chung-Jansen syndrome (CHUJANS) from all over Europe. Follow-up investigations (e.g. Sanger sequencing, qPCR or Fluorescence-in-situ-Hybridization) and segregation analysis showed either de novo occurrence or inheritance from an also (mildly) affected parent. In accordance with previously described patients, almost all individuals reported here show developmental delay (22/23), learning disability or ID (22/23), behavioral abnormalities (20/23), weight problems (13/23) and characteristic craniofacial features (i.e. large ears/earlobes, prominent eyebrows, anteverted nares and long philtrum (23/23)). To further investigate the facial gestalt of individuals with CHUJANS, we performed facial analysis using the GestaltMatcher approach. By this, we could establish that PHIP patients are indistinguishable based on the type of PHIP alteration (e.g. missense, loss-of-function, splice site) but show a significant difference to the average face of healthy individuals as well as to individuals with Prader-Willi syndrome (PWS, OMIM #176270) or with a CUL4B-alteration (Intellectual developmental disorder, X-linked, syndromic, Cabezas type, OMIM #300354). Our findings expand the mutational and clinical spectrum of CHUJANS. We discuss the molecular and clinical features in comparison to the published individuals. The fact that some variants were inherited from a mildly affected parent further illustrates the variability of the associated phenotype and outlines the importance of a thorough clinical evaluation combined with genetic analyses for accurate diagnosis and counselling.

Risk of mayor and minor birth defects in children conceived by assisted reproductive technology (IVF/ICSI): A prospective controlled cohort study.

INTRODUCTION: About 0.2-6.1% of newborns in the developed world have been conceived by assisted reproductive techniques (ART). Higher rate of major and minor malformations have been described in this population, but the multiple possible confounders associated make it difficult to establish a direct causal relationship and the specific factors involved. MATERIAL AND METHODS: To determine the risk of these malformations in our population, a collaborative prospective controlled cohort study was designed. We collected the specific ART-data related to the clinical gestation of women treated in a period of 2 years in the Reproduction Unit from a Spanish public tertiary-level hospital. 231 out of 267 newborns of these gestation (88%) participated in the study and were assessed by a pediatrician with expertise in Clinical Genetics and Dysmorphology at 12-20 and 26-40 months of age. At the same time a controlled group of children naturally conceived (NC) was selected according to the following criteria: the next NC newborn belonging to the same group of maternal and gestational age, and type of gestation (single or multiple). 230 controls were chosen and 208 participated in the study (90%). RESULTS: Major malformations were presented in 7.8% of the ART-children and 7.2% of the controls, without founding statistically differences between groups. However, differences were found in the risk of some minor malformations such as capillary malformations and pigmentary lesions, higher in the ART-group. A recurrent pattern of craneofacial anomalies was also unexpectedly detected. CONCLUSIONS: In spite of the high rate of major congenital malformations detected, there were no differences between groups. Thus, our results suggest that ART may affect the normal embryonic development but in a milder way than other confounding factors do. The facial phenotype identified has not previously been described, either the higher risk of capillary malformations and pigmentary lesions. More studies are needed to confirm this association.

[Risk of mayor and minor birth defects in children conceived by assisted reproductive technology (IVF/ICSI): A prospective controlled cohort study]. / Riesgo de malformaciones mayores y menores en niños concebidos por técnicas de reproducción asistida (FIV/ICSI): estudio prospectivo de cohorte controlado.

INTRODUCTION: About 0.2-6.1% of newborns in the developed world have been conceived by assisted reproductive techniques (ART). Higher rate of major and minor malformations have been described in this population, but the multiple possible confounders associated, make it difficult to establish a direct causal relationship, and the specific factors involved. MATERIAL AND METHODS: To determine the risk of these malformations in our population, a collaborative prospective controlled cohort study was designed. We collected the specific ART-data related to the clinical gestation of women treated in a period of 2 years in the Reproduction Unit from a Spanish public tertiary-level hospital. 231 out of 267 newborns of these gestation (88%) were exhausted assessed by a Clinical Geneticist expertise in Dysmorphology at 12-20 and 26-40 months of age. At the same time a controlled group of children naturally conceived (NC) was selected according to the following criteria: the next NC newborn belonging to the same group of maternal and gestational age, and type of gestation (single or multiple). 230 controls were chosen and 208 participated in the study (90%). RESULTS: Major malformations were presented in 7.8% of the ART-children and 7.2% of the controls, without founding statistically differences between groups. However, differences were found in the risk of some minor malformations such as capillary malformations and pigmentary lesions, higher in the ART-group. A recurrent pattern of craneofacial anomalies was also unexpectedly detected. CONCLUSIONS: In spite of the high rate of major congenital malformations detected, there were no differences between groups. Thus, our results suggest that ART may affect the normal embryonic development but in a milder way than other confounding factors do. The facial phenotype identified has not previously, either the higher risk of capillary malformations and pigmentary lesions. More studies are needed to confirm this association.

Health impact of acute intermittent porphyria in latent and non-recurrent attacks patients.

BACKGROUND: Acute intermittent porphyria (AIP) is a genetic disease characterized by acute neurovisceral attacks. Long-term clinical conditions, chronic symptoms and impaired health related quality of life (HRQoL) have been reported during non-attack periods but mainly in patients with recurrent attacks. Our aim was to investigate these aspects in sporadic AIP (SA-AIP) and latent AIP (L-AIP) patients. Fifty-five participants, 27 SA-AIP (< 4 attacks/year) and 28 L-AIP patients with a prevalent founder mutation from Spain were included. Medical records were reviewed, and individual interviews, physical examinations, biochemical analyses, and abdominal ultrasound scans were conducted. HRQoL was assessed through an EQ-5D-5L questionnaire. A comparative study was made between SA-AIP and L-AIP patients. RESULTS: The earliest long-term clinical condition associated with SA-AIP was chronic kidney disease. Chronic symptoms were reported in 85.2 % of SA-AIP and 46.4 % of L-AIP patients. Unspecific abdominal pain, fatigue, muscle pain and insomnia were significantly more frequent in SA-AIP than in L-AIP patients. The EQ-5D-5L index was lower in SA-AIP (0.809 vs. 0.926, p = 0.0497), and the impact of "pain", "anxiety-depression" and "mobility" was more intense in the EQ-5D-5L domains in SA-AIP than in L-AIP subjects and the general Spanish population. CONCLUSIONS: AIP remains a chronically symptomatic disease that adversely affects health and quality of life, even in patients with low rate of acute attacks. We suggest a regular monitoring of patients with symptomatic AIP regardless of their attack rate or the time since their last attack, with proper pain management and careful attention to kidney function.

Expanding the phenotype of CRYAA nucleotide variants to a complex presentation of anterior segment dysgenesis.

BACKGROUND: Mutations in CRYAA, which encodes the α-crystallin protein, are associated with a spectrum of congenital cataract-microcornea syndromes. RESULTS: In this study, we performed clinical examination and subsequent genetic analysis in two unrelated sporadic cases of different geographical origins presenting with a complex phenotype of ocular malformation. Both cases manifested bilateral microphthalmia and severe anterior segment dysgenesis, primarily characterized by congenital aphakia, microcornea, and iris hypoplasia/aniridia. NGS-based analysis revealed two novel single nucleotide variants occurring de novo and affecting the translation termination codon of the CRYAA gene, c.520T > C and c.521A > C. Both variants are predicted to elongate the C-terminal protein domain by one-third of the original length. CONCLUSIONS: Our report not only expands the mutational spectrum of CRYAA but also identifies the genetic cause of the unusual ocular phenotype described in this report.

TCF12 haploinsufficiency causes autosomal dominant Kallmann syndrome and reveals network-level interactions between causal loci.

Dysfunction of the gonadotropin-releasing hormone (GnRH) axis causes a range of reproductive phenotypes resulting from defects in the specification, migration and/or function of GnRH neurons. To identify additional molecular components of this system, we initiated a systematic genetic interrogation of families with isolated GnRH deficiency (IGD). Here, we report 13 families (12 autosomal dominant and one autosomal recessive) with an anosmic form of IGD (Kallmann syndrome) with loss-of-function mutations in TCF12, a locus also known to cause syndromic and non-syndromic craniosynostosis. We show that loss of tcf12 in zebrafish larvae perturbs GnRH neuronal patterning with concomitant attenuation of the orthologous expression of tcf3a/b, encoding a binding partner of TCF12, and stub1, a gene that is both mutated in other syndromic forms of IGD and maps to a TCF12 affinity network. Finally, we report that restored STUB1 mRNA rescues loss of tcf12 in vivo. Our data extend the mutational landscape of IGD, highlight the genetic links between craniofacial patterning and GnRH dysfunction and begin to assemble the functional network that regulates the development of the GnRH axis.

Heterozygous pathogenic variants in GLI1 are a common finding in isolated postaxial polydactyly A/B.

Postaxial polydactyly (PAP) is a frequent limb malformation consisting in the duplication of the fifth digit of the hand or foot. Morphologically, this condition is divided into type A and B, with PAP-B corresponding to a more rudimentary extra-digit. Recently, biallelic truncating variants in the transcription factor GLI1 were reported to be associated with a recessive disorder, which in addition to PAP-A, may include syndromic features. Moreover, two heterozygous subjects carrying only one inactive copy of GLI1 were also identified with PAP. Herein, we aimed to determine the level of involvement of GLI1 in isolated PAP, a condition previously established to be autosomal dominantly inherited with incomplete penetrance. We analyzed the coding region of GLI1 in 95 independent probands with nonsyndromic PAP and found 11.57% of these subjects with single heterozygous pathogenic variants in this gene. The detected variants lead to premature termination codons or result in amino acid changes in the DNA-binding domain of GLI1 that diminish its transactivation activity. Family segregation analysis of these variants was consistent with dominant inheritance with incomplete penetrance. We conclude that heterozygous changes in GLI1 underlie a significant proportion of sporadic or familial cases of isolated PAP-A/B.

[Assessment of psychomotor development of Spanish children up to 3 years of age conceived by assisted reproductive techniques: Prospective matched cohort study]. / Evaluación del desarrollo psicomotor hasta los 3 años de edad de niños españoles concebidos por técnicas de reproducción asistida (FIV/ICSI): estudio prospectivo de cohorte controlado.

INTRODUCTION: More than five million children have been conceived by assisted reproductive techniques (ART) around the world. Most authors agree that there are no differences in psychomotor development in comparison to naturally conceived children. However, these results are still contradictory. OBJECTIVE: To determine whether children born from a cohort of ART-clinical gestations have a higher risk of suffering neurodevelopmental disorders in comparison to a control group. The potential associated ART-factors associated were also determined. MATERIAL AND METHODS: The study included the assessment of children up to 3 years old conceived by ART, and born from a cohort of women treated by the reproduction unit of a public hospital from May 2012 to May 2014. A simultaneous assessment was made of matched controls, by following the newborn naturally conceived after the ART-case, of the same group of maternal age, gestational age, and type of gestation. RESULTS: There were 243 clinical gestations and 267 ART-newborns, of which 231 were assessed (87%). A simultaneous assessment was carried out in 208/230 controls (90%). There were no differences in neurodevelopmental disorders (global developmental delay, autism spectrum or language delay). Multivariate analysis of potential ART factors only showed an association between transfer of frozen embryos with language delay that has not been previously described. CONCLUSIONS: There were no differences between groups after adjusting the results according to maternal age, multiple pregnancy, and other possible confounding factors, supporting that the role of these factors may be more relevant than the ART itself. The association between frozen embryo transfer and language delay has not been previously described. Thus, more studies are needed to confirm or refute this relationship.

EDA, EDAR, EDARADD and WNT10A allelic variants in patients with ectodermal derivative impairment in the Spanish population.

BACKGROUND: Ectodermal dysplasias (ED) are a group of genetic conditions affecting the development and/or homeostasis of two or more ectodermal derivatives. An attenuated phenotype is considered a non-syndromic trait when the patient is affected by only one impaired ectodermal structure, such as in non-syndromic tooth agenesis (NSTA) disorder. Hypohidrotic ectodermal dysplasia (HED) is the most highly represented ED. X-linked hypohidrotic ectodermal dysplasia (XLHED) is the most common subtype, with an incidence of 1/50,000-100,000 males, and is associated with the EDA gene (Xq12-q13.1); the dominant and recessive subtypes involve the EDAR (2q13) and EDARADD (1q42.3) genes, respectively. The WNT10A gene (2q35) is associated more frequently with NSTA. Our goal was to determine the mutational spectrum in a cohort of 72 Spanish patients affected by one or more ectodermal derivative impairments referred to as HED (63/72) or NSTA (9 /72) to establish the prevalence of the allelic variants of the four most frequently associated genes. Sanger sequencing of the EDA, EDAR, EDARADD and WNT10A genes and multiplex ligation-dependent probe amplification (MLPA) were performed. RESULTS: A total of 61 children and 11 adults, comprising 50 males and 22 females, were included. The average ages were 5.4 and 40.2 years for children and adults, respectively. A molecular basis was identified in 51/72 patients, including 47/63 HED patients, for whom EDA was the most frequently involved gene, and 4/9 NSTA patients, most of whom had variants of WNT10A. Among all the patients, 37/51 had variants of EDA, 8/51 had variants of the WNT10A gene, 4/51 had variants of EDAR and 5/51 had variants of EDARADD. In 42/51 of cases, the variants were inherited according to an X-linked pattern (27/42), with the remaining showing an autosomal dominant (10/42) or autosomal recessive (5/42) pattern. Among the NSTA patients, 3/9 carried pathogenic variants of WNT10A and 1/9 carried EDA variants. A total of 60 variants were detected in 51 patients, 46 of which were different, and out of these 46 variants, 12 were novel. CONCLUSIONS: This is the only molecular study conducted to date in the Spanish population affected by ED. The EDA, EDAR, EDARADD and WNT10A genes constitute the molecular basis in 70.8% of patients with a 74.6% yield in HED and 44.4% in NSTA. Twelve novel variants were identified. The WNT10A gene has been confirmed as the second molecular candidate that has been identified and accounts for one-half of non-EDA patients and one-third of NSTA patients. Further studies using next generation sequencing (NGS) will help to identify other contributory genes in the remaining uncharacterized Spanish patients.

High penetrance of acute intermittent porphyria in a Spanish founder mutation population and CYP2D6 genotype as a susceptibility factor.

BACKGROUND: Acute intermittent porphyria (AIP) is a low-penetrant genetic metabolic disease caused by a deficiency of hydroxymethylbilane synthase (HMBS) in the haem biosynthesis. Manifest AIP (MAIP) is considered when carriers develop typical acute neurovisceral attacks with elevation of porphyrin precursors, while the absence of attacks is referred to as latent AIP (LAIP). Attacks are often triggered by drugs, endocrine factors, fasting or stress. Although AIP penetrance is traditionally considered to be around 10-20%, it has been estimated to be below 1% in general population studies and a higher figure has been found in specific AIP populations. Genetic susceptibility factors underlying penetrance are still unknown. Drug-metabolizing cytochrome P450 enzymes (CYP) are polymorphic haem-dependent proteins which play a role in haem demand, so they might modulate the occurrence of AIP attacks. Our aim was to determine the prevalence and penetrance of AIP in our population and analyse the main hepatic CYP genes to assess their association with acute attacks. For this, CYP2C9*2, *3; CYP2C19*2; CYP2D6*4, *5; CYP3A4*1B and CYP3A5*3 defective alleles were genotyped in fifty AIP carriers from the Region of Murcia, a Spanish population with a high frequency of the HMBS founder mutation c.669_698del30. RESULTS: AIP penetrance was 52%, and prevalence was estimated as 17.7 cases/million inhabitants. The frequency of defective CYP2D6 alleles was 3.5 times higher in LAIP than in MAIP. MAIP was less frequent among CYP2D6*4 and *5 carriers (p < 0.05). The urine porphobilinogen (PBG)-to-creatinine ratio was lower in these individuals, although it was associated with a lower prevalence of attacks (p < 0.05) rather than with the CYP2D6 genotype. CONCLUSIONS: AIP prevalence in our region is almost 3 times higher than that estimated for the rest of Spain. The penetrance was high, and similar to other founder mutation AIP populations. This is very relevant for genetic counselling and effective health care. CYP2D6*4 and *5 alleles may be protective factors for acute attacks, and CYP2D6 may constitute a penetrance-modifying gene. Further studies are needed to confirm these findings, which would allow a further progress in clinical risk profile assessment based on the CYP genotype, leading to predictive personalized medicine for each AIP carrier in the future.

Correction: The ARID1B spectrum in 143 patients: from nonsyndromic intellectual disability to Coffin-Siris syndrome.

The original version of this Article contained an error in the spelling of the author Pleuntje J. van der Sluijs, which was incorrectly given as Eline (P. J.) van der Sluijs. This has now been corrected in both the PDF and HTML versions of the Article.