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In the era of precision medicine, genome sequencing (GS) has become more affordable and the importance of genomics and multi-omics in clinical care is increasingly being recognized. However, how to scale and effectively implement GS on an institutional level remains a challenge for many. Here, we present Genome First and Ge-Med, two clinical implementation studies focused on identifying the key pillars and processes that are required to make routine GS and predictive genomics a reality in the clinical setting. We describe our experience and lessons learned for a variety of topics including test logistics, patient care processes, data reporting, and infrastructure. Our model of providing clinical care and comprehensive genomic analysis from a single source may be used by other centers with a similar structure to facilitate the implementation of omics-based personalized health concepts in medicine.

Schinzel-Giedion syndrome (SGS) is a rare developmental disorder characterized by multiple malformations, severe neurological alterations and increased risk of malignancy. SGS is caused by de novo germline mutations clustering to a 12bp hotspot in exon 4 of SETBP1. Mutations in this hotspot disrupt a degron, a signal for the regulation of protein degradation, and lead to the accumulation of SETBP1 protein. Overlapping SETBP1 hotspot mutations have been observed recurrently as somatic events in leukemia. We collected clinical information of 47 SGS patients (including 26 novel cases) with germline SETBP1 mutations and of four individuals with a milder phenotype caused by de novo germline mutations adjacent to the SETBP1 hotspot. Different mutations within and around the SETBP1 hotspot have varying effects on SETBP1 stability and protein levels in vitro and in in silico modeling. Substitutions in SETBP1 residue I871 result in a weak increase in protein levels and mutations affecting this residue are significantly more frequent in SGS than in leukemia. On the other hand, substitutions in residue D868 lead to the largest increase in protein levels. Individuals with germline mutations affecting D868 have enhanced cell proliferation in vitro and higher incidence of cancer compared to patients with other germline SETBP1 mutations. Our findings substantiate that, despite their overlap, somatic SETBP1 mutations driving malignancy are more disruptive to the degron than germline SETBP1 mutations causing SGS. Additionally, this suggests that the functional threshold for the development of cancer driven by the disruption of the SETBP1 degron is higher than for the alteration in prenatal development in SGS. Drawing on previous studies of somatic SETBP1 mutations in leukemia, our results reveal a genotype-phenotype correlation in germline SETBP1 mutations spanning a molecular, cellular and clinical phenotype.

Background Pregnancy and family planning for individuals living with rare and low prevalence diseases present unique medical, psychological, and logistical challenges. The European Reference Networks (ERNs) were established to address healthcare disparities and enhance patient care for rare diseases across Europe. The ERN Transversal Working Group on Pregnancy and Family Planning was created to identify common unmet needs and to develop targeted actions to improve healthcare delivery. As part of this initiative, a survey was conducted to gather insights from patients, caregivers, and family members about their experiences and challenges related to pregnancy and family planning. Methods The survey was co-designed by healthcare professionals and patient representatives from 20 ERNs. It covered various domains, including fertility preservation, pre-conceptional counselling, psychological support in the pre-conceptional counselling, pre-implantation diagnosis, prenatal diagnosis, family planning, pregnancy monitoring, post-pregnancy monitoring, lactation and newborn management. The survey, available in multiple languages, was distributed via online platforms between February and July 2022. Quantitative responses were analysed descriptively, while qualitative data from open-ended questions were processed using word frequency analysis. Results A total of 769 responses were collected, with 574 from patients and 155 from caregivers. The majority of respondents were female (90%) and aged 31–40 years, primarily from Germany, France, Spain, and Italy. The most pressing concerns identified included lack of access to accurate medical information, limited psychological support, inadequate pre-conceptional counselling, and challenges related to pregnancy monitoring and postpartum care. The need for multidisciplinary healthcare teams and improved education on reproductive health was emphasised. Word frequency analysis highlighted key concerns, with “inform,” “support,” and “risk” being the most recurrent terms. Conclusions This study underscores the widespread need for comprehensive, patient-centred approaches in pregnancy and family planning for individuals with rare and low prevalence diseases. Improved access to specialised healthcare teams, psychological support, and clear, standardised medical information is essential. These findings advocate for the development of harmonised European policies and multidisciplinary strategies to enhance reproductive healthcare. Plain english Language summary People living with rare diseases often face extra challenges when it comes to pregnancy and family planning. To better understand these issues, a group of experts and patient representatives from 20 European Reference Networks (ERNs) worked together to conduct a survey. A European survey of 769 people, mostly women aged 31 to 40 from Germany, France, Spain, and Italy, revealed significant gaps in care. The most common concerns shared by patients included difficulty finding clear medical information, not enough psychological support, gaps in counselling, and challenges with checking on health during and after pregnancy. Many felt that better teamwork among different healthcare providers and improved education on reproductive health would make a big difference. In summary, this study underscores the urgent need for better reproductive healthcare for people with rare diseases.

Background Copy number variants (CNVs) are the genetic bases for microdeletion/ microduplication syndromes (MMSs). Couples with an affected child and desire to have further children are routinely tested for a potential parental origin of a specific CNV either by molecular karyotyping or by two color fluorescence in situ hybridization (FISH), yet. In the latter case a critical region probe (CRP) is combined with a control probe for identification of the chromosome in question. However, CNVs can arise also due to other reasons, like a recombination-event based on a submicroscopic, cryptic inversion in one of the parents. Results Seventy-four patients with different MMSs and overall 81 CNVs were studied here by a novel three color FISH approach. The way how three locus-specific probes are selected (one is the CRP and two are flanking it in a distance of 5-10 Mb) enables to detect or exclude two possible parental conditions as origins of the CNV seen in the index: (i) direct parental origin of the CNV (deletion or duplication) or (ii) a parental cryptic inversion. Thus, for overall 51/81 CNVs (63%) a parental origin could be determined. 36/51 (70.5%) inherited the CNV directly from one of the parents, but 15/51 (29.5%) were due to an exclusively by three color FISH detectable parental inversion. A 2:1 ratio of maternal versus paternal inheritance was found. Also almost two times more male than female were among the index patients. Conclusion The new, here suggested three color FISH approach is suited for more comprehensive parental studies of patients with MMS. The detection rate for parental origin was increased by 140% in this study. Still, for 30/81 cases (37%) no reason for the ‘de novo’ MMS in the affected index patient could be found by the here suggested FISH-probe set.

Small supernumerary marker chromosomes (SMCs) are present in about 0.05% of the human population. In approximately 30% of SMC carriers (excluding the approximately 60% SMC derived from one of the acrocentric chromosomes), an abnormal phenotype is observed. The clinical outcome of an SMC is difficult to predict as they can have different phenotypic consequences because of (1). differences in euchromatic DNA-content, (2). different degrees of mosaicism, and/or (3). uniparental disomy (UPD) of the chromosomes homologous to the SMC. Here, we present 35 SMCs, which are derived from all human chromosomes, apart from chromosome 6, as demonstrated by the appropriate molecular cytogenetic approaches, such as centromere-specific multicolor fluoresence in situ hybridization (cenM-FISH), multicolor banding (MCB), and subcentromere-specific multicolor FISH (subcenM-FISH). In nine cases without an aberrant phenotype, neither partial proximal trisomies nor UPD could be detected. Abnormal clinical findings, such as psychomotoric retardation and/or craniofacial dysmorphisms, were associated with seven of the cases in which subcentromeric single-copy probes were proven to be present in three copies. Conversely, in eight cases with a normal phenotype, proximal euchromatic material was detected as partial trisomy. UPD was studied in 12 cases and subsequently detected in two of the cases with SMC (partial UPD 4p and maternal UPD 22 in a der(22)-syndrome patient), indicating that SMC carriers have an enhanced risk for UPD. At present, small proximal trisomies of 1p, 1q, 2p, 6p, 6q, 7q, 9p, and 12q seem to lead to clinical manifestations, whereas partial proximal trisomies of 2q, 3p, 3q, 5q, 7p, 8p, 17p, and 18p may not be associated with significant clinical symptoms. With respect to clinical outcome, a classification of SMCs is proposed that considers molecular genetic and molecular cytogenetic characteristics as demonstrated by presently available methods.

X-linked intellectual disability (XLID) is a genetically heterogeneous disorder with more than 100 genes known to date. Most genes are responsible for a small proportion of patients only, which has hitherto hampered the systematic screening of large patient cohorts. We performed targeted enrichment and next-generation sequencing of 107 XLID genes in a cohort of 150 male patients. Hundred patients had sporadic intellectual disability, and 50 patients had a family history suggestive of XLID. We also analysed a sporadic female patient with severe ID and epilepsy because she had strongly skewed X-inactivation. Target enrichment and high parallel sequencing allowed a diagnostic coverage of >10 reads for ~96% of all coding bases of the XLID genes at a mean coverage of 124 reads. We found 18 pathogenic variants in 13 XLID genes (AP1S2, ATRX, CUL4B, DLG3, IQSEC2, KDM5C, MED12, OPHN1, SLC9A6, SMC1A, UBE2A, UPF3B and ZDHHC9) among the 150 male patients. Thirteen pathogenic variants were present in the group of 50 familial patients (26%), and 5 pathogenic variants among the 100 sporadic patients (5%). Systematic gene dosage analysis for low coverage exons detected one pathogenic hemizygous deletion. An IQSEC2 nonsense variant was detected in the female ID patient, providing further evidence for a role of this gene in encephalopathy in females. Skewed X-inactivation was more frequently observed in mothers with pathogenic variants compared with those without known X-linked defects. The mutation rate in the cohort of sporadic patients corroborates previous estimates of 5-10% for X-chromosomal defects in male ID patients.

The genetic cause of intellectual disability in most patients is unclear because of the absence of morphological clues, information about the position of such genes, and suitable screening methods. Our aim was to identify de-novo variants in individuals with sporadic non-syndromic intellectual disability. In this study, we enrolled children with intellectual disability and their parents from ten centres in Germany and Switzerland. We compared exome sequences between patients and their parents to identify de-novo variants. 20 children and their parents from the KORA Augsburg Diabetes Family Study were investigated as controls. We enrolled 51 participants from the German Mental Retardation Network. 45 (88%) participants in the case group and 14 (70%) in the control group had de-novo variants. We identified 87 de-novo variants in the case group, with an exomic mutation rate of 1·71 per individual per generation. In the control group we identified 24 de-novo variants, which is 1·2 events per individual per generation. More participants in the case group had loss-of-function variants than in the control group (20/51 vs 2/20; p=0·022), suggesting their contribution to disease development. 16 patients carried de-novo variants in known intellectual disability genes with three recurrently mutated genes (STXBP1, SYNGAP1, and SCN2A). We deemed at least six loss-of-function mutations in six novel genes to be disease causing. We also identified several missense alterations with potential pathogenicity. After exclusion of copy-number variants, de-novo point mutations and small indels are associated with severe, sporadic non-syndromic intellectual disability, accounting for 45–55% of patients with high locus heterogeneity. Autosomal recessive inheritance seems to contribute little in the outbred population investigated. The large number of de-novo variants in known intellectual disability genes is only partially attributable to known non-specific phenotypes. Several patients did not meet the expected syndromic manifestation, suggesting a strong bias in present clinical syndrome descriptions. German Ministry of Education and Research, European Commission 7th Framework Program, and Swiss National Science Foundation.

To date, uniparental disomy (UPD) with phenotypic relevance is described for different chromosomes and it is likely that additional as yet unidentified UPD phenotypes exist. Due to technical difficulties and limitations of time and resources, molecular analyses for UPD using microsatellite markers are only performed in cases with specific phenotypic features. In this study, we carried out a whole genome UPD screening based on a microarray genotyping technique. Six patients with the diagnosis of both complete or segmental UPD including Prader‐Willi syndrome (PWS; matUPD15), Angelman syndrome (AS; patUPD15), Silver‐Russell syndrome (SRS; matUPD7), Beckwith‐Wiedemann syndrome (BWS; patUPD11p), pseudohypoparathyroidism (PHP; patUPD20q) and a rare chromosomal rearrangement (patUPD2p, matUPD2q), were genotyped using the GeneChip® Human Mapping 10K Array. Our results demonstrate the presence of UPD in the patients with high efficiency and reveal clues about the mechanisms of UPD formation. We thus conclude that array based SNP genotyping is a fast, cost‐effective, and reliable approach for whole genome UPD screening. Hum Mutat 26(2), 1–7, 2005. © 2005 Wiley‐Liss, Inc.

Most patients with a rare movement disorder (MD) do not receive a molecular diagnosis, and the underlying genetic variants and mediating genes remain elusive. Here, we evaluate the diagnostic accuracy of conventional and next-generation sequencing-based genetic testing strategies in a cohort of 2,811 individuals with ataxia, spastic paraplegia and dystonia. Exome sequencing establishes genetic diagnoses in 19.3% of cases, and specificity of phenotypic features and age at testing are positive predictors. Genome analysis ‘beyond the exome’ increases the diagnostic yield by 7.5%, mostly due to the improved detection of structural variants and repeat expansions. Unsolved cases are included in the Solve-RD cohort and subjected to gene-burden analysis, providing evidence for loss-of-function variants in X-chromosomal CD99L2 causing spastic ataxia. Cellular studies show that the transmembrane protein CD99L2 occurs mainly in a ubiquitinated form and serves as an activating interactor of the calcium-dependent protease CAPN1. Ablation of cytoplasmic or extracellular domains of CD99L2 leads to its intracellular mislocalization and abrogation of its interplay with CAPN1. Transcriptome analysis in CD99L2 patient-derived fibroblasts reveals synaptic function-specific disturbances. Impaired CAPN1 activation and dysregulation of downstream neuronal pathways constitute the likely molecular cause for neurodegeneration. Here the authors compare genetic testing strategies in rare movement disorders, improve diagnostic yield with genome analysis, and establish CD99L2 as an X-linked spastic ataxia gene, showing that CD99L2–CAPN1 signaling disruption likely drives neurodegeneration.