Sulfate: a neglected (but potentially highly relevant) anion.

Sulfate is an important anion as sulfonation is essential in modulation of several compounds, such as exogens, polysaccharide chains of proteoglycans, cholesterol or cholesterol derivatives and tyrosine residues of several proteins. Sulfonation requires the presence of both the sulfate donor 3'-phosphoadenosine-5'-phosphosulfate (PAPS) and a sulfotransferase. Genetic disorders affecting sulfonation, associated with skeletal abnormalities, impaired neurological development and endocrinopathies, demonstrate the importance of sulfate. Yet sulfate is not measured in clinical practice. This review addresses sulfate metabolism and consequences of sulfonation defects, how to measure sulfate and why we should measure sulfate more often.

Aggrecan-related bone disorders; a novel heterozygous ACAN variant associated with spondyloepimetaphyseal dysplasia expanding the phenotypic spectrum and review of literature.

BACKGROUND: Spondyloepimetaphyseal dysplasias (SEMD) are a large group of skeletal disorders represented by abnormalities of vertebrae in addition to epiphyseal and metaphyseal areas of bones. Several genes have been identified underlying different forms. ACAN gene mutations were found to cause Aggrecan-related bone disorders (spondyloepimetaphyseal dysplasias,spondyloepiphyseal dysplasias, familial osteochondritis dissecans and short stature syndromes). This study aims to find the disease causing variant in Egyptian patient with SEMD using whole exome sequencing. METHODS: Whole-exome sequencing was performed for an Egyptian male patient who presented with short stature, clinical and radiological features suggestive of unclassified SEMD. RESULTS: The study identified a novel de novo heterozygous ACAN gene variant (c.7378G>A; p.Gly2460Arg) in G3 domain. Mutations in ACAN gene have been more commonly associated with short stature than SEMD. The phenotype of our patient was intermediate in severity between spondyloepiphyseal dysplasia presentation; Kimberley type(SEDK) and Spondyloepimetaphyseal dysplasias Aggrecan (SEMDAG) CONCLUSIONS: Whole exome sequencing revealed a novel de novo ACAN gene variant in patient with SEDK. The clinical and skeletal phenotype of our patient was much severe than those reported originally and showed more metaphyseal involvement. To the best of our knowledge, two previous studies reported a heterozygous variant in ACAN with spondyloepiphyseal dysplasia presentation; Kimberley type.

Multi-gene panel sequencing in highly consanguineous families and patients with congenital forms of skeletal dysplasias.

Skeletal dysplasias (SKDs) are a heterogeneous group of more than 750 genetic disorders characterized by abnormal development, growth, and maintenance of bones or cartilage in the human skeleton. SKDs are often caused by variants in early patterning genes and in many cases part of multiple malformation syndromes and occur in combination with non-skeletal phenotypes. The aim of this study was to investigate the underlying genetic cause of congenital SKDs in highly consanguineous Pakistani families, as well as in sporadic and familial SKD cases from India using multigene panel sequencing analysis. Therefore, we performed panel sequencing of 386 bone-related genes in 7 highly consanguineous families from Pakistan and 27 cases from India affected with SKDs. In the highly consanguineous families, we were able to identify the underlying genetic cause in five out of seven families, resulting in a diagnostic yield of 71%. Whereas, in the sporadic and familial SKD cases, we identified 12 causative variants, corresponding to a diagnostic yield of 44%. The genetic heterogeneity in our cohorts was very high and we were able to detect various types of variants, including missense, nonsense, and frameshift variants, across multiple genes known to cause different types of SKDs. In conclusion, panel sequencing proved to be a highly effective way to decipher the genetic basis of SKDs in highly consanguineous families as well as sporadic and or familial cases from South Asia. Furthermore, our findings expand the allelic spectrum of skeletal dysplasias.

Primary cilia in skeletal development and disease.

Primary cilia are non-motile, microtubule-based sensory organelle present in most vertebrate cells with a fundamental role in the modulation of organismal development, morphogenesis, and repair. Here we focus on the role of primary cilia in embryonic and postnatal skeletal development. We examine evidence supporting its involvement in physiochemical and developmental signaling that regulates proliferation, patterning, differentiation and homeostasis of osteoblasts, chondrocytes, and their progenitor cells in the skeleton. We discuss how signaling effectors in mechanotransduction and bone development, such as Hedgehog, Wnt, Fibroblast growth factor and second messenger pathways operate at least in part at the primary cilium. The relevance of primary cilia in bone formation and maintenance is underscored by a growing list of rare genetic skeletal ciliopathies. We collate these findings and summarize the current understanding of molecular factors and mechanisms governing primary ciliogenesis and ciliary function in skeletal development and disease.

Accuracy of Multimodality Fetal Imaging (US, MRI, and CT) for Congenital Musculoskeletal Anomalies.

BACKGROUND: Ultrasonography (US) is the first-line diagnostic tool used to assess fetal musculoskeletal (MSK) anomalies. Associated anomalies in other organ systems may benefit from evaluation via Magnetic Resonance Imaging (MRI). In this study, we compared the diagnostic accuracy of US and MRI to diagnose fetal MSK (primary objective) and non-MSK anomalies (secondary objective). We describe additional findings by low-dose computerized tomography (CT) in two cases incompletely characterized via US and MRI. MATERIALS AND METHODS: This was an IRB-approved retrospective study of consecutive patients with suspected fetal MSK anomalies examined between December 2015 and June 2020. We compared individual MSK and non-MSK anomalies identified via US, MRI, and CT with postnatal outcomes. Sensitivity and specificity for US and MRI were calculated and compared. RESULTS: A total of 31 patients with 112 MSK and 43 non-MSK anomalies were included. The sensitivity of MRI and US for MSK anomalies was not significantly different (76.6% vs. 61.3%, p = 0.3). Low-dose CT identified eight additional skeletal anomalies. MRI diagnosed a higher number of non-MSK anomalies compared to US (81.4% vs. 37.2%, p < 0.05). CONCLUSIONS: Fetal MRI and US have comparable sensitivity for MSK anomalies. In selected cases, low-dose CT may provide additional information. Fetal MRI detected a larger number of non-MSK anomalies in other organ systems compared to US. Multimodality imaging combining all the information provided by MRI, US, and CT, if necessary, ultimately achieved a sensitivity of 89.2% (95% CI: 83.4% to 95.0%) for the diagnosis of musculoskeletal anomalies and 81.4% for additional anomalies in other organs and systems.

Fetal skeletal dysplasia cohort of a single tertiary referral center in Istanbul, Turkey.

We report on 314 fetal cases from 297 unrelated families with skeletal dysplasia evaluated in the postmortem period from 2000 to 2017 at a single clinical genetics center in Istanbul, Turkey. The definite diagnostic yield was 40% during the prenatal period, while it reached 74.5% when combined with postmortem clinical and radiological evaluation. Molecular analyses were performed in 25.5% (n: 76) of families, and 21 novel variants were identified. Classification according to International Skeletal Dysplasia Society-2019 revision revealed limb hypoplasia-reduction defects group (39) as the leading one, 24.5%, then followed by FGFR3 chondrodysplasias, osteogenesis imperfecta, and decreased mineralization and polydactyly-syndactyly-triphalangism groups 13.6, 11.1, and 8.9%, respectively. The inheritance pattern was autosomal recessive in 54% and autosomal dominant in 42.6% of index cases. The overall consanguinity rate of the cohort was 33%. The high prevalence of ultrarare diseases along with two or more unrelated autosomal recessive entities running in the same family was noteworthy. This study highlights the pivotal role of postmortem evaluation by an experienced clinical geneticist to achieve a high diagnostic yield in fetal skeletal dysplasia cohorts. The cohort is not only a representation of the spectrum of skeletal dysplasias in a population with a high consanguinity rate but also provides an ideal research group to work on to identify the unknowns of early fetal life.

Computational biology insights into genotype-clinical phenotype-protein phenotype relationships between novel SLC26A2 variants identified in inherited skeletal dysplasias.

BACKGROUND: Pathogenic variants in the transmembrane sulfate transporter protein SLC26A2 are associated with different phenotypes of inherited chondrodysplasias. As limited data is published from India, in this study we sought to elucidate the molecular basis of inherited chondrodysplasias in an Indian cohort. METHODS: Molecular screening of 32 fetuses with antenatally diagnosed lethal skeletal dysplasia was performed by next generation sequencing and Sanger sequencing. The genotype-protein phenotype characterization was done using computational biology techniques like homology modelling, stability and pathogenicity predictions. RESULTS: We identified five rare autosomal recessive SLC26A2 [NM_000112.4] variants, including three homozygous c.796dupA(p.Thr266Asnfs*12), c.1724delA(p.Lys575Serfs*10), and c.1375_1377dup(p.Val459dup) and two heterozygous variants (c.532C > T(p.Arg178*)) and (c.1382C > T(p.Ala461Val)) in compound heterozygous form in a total of four foetuses. Genotype-protein phenotype annotations highlighted that the clinically severe achondrogenesis 1B causative c.796dupA(p.Thr266Asnfs*12) and c.1724delA(p.Lys575Serfs*10)variants impact SLC26A2 protein structure by deletion of the protein core and transmembrane STAS domains, respectively. In clinically moderate atelosteogenesis type 2 phenotype, the c.1382C > T(p.Ala461Val) variant is predicted to distort alpha helix conformation and alter the bonding properties and free energy dynamics of transmembrane domains and the c.532C > T(p.Arg178*) variant results in loss of both core transmembrane and STAS domains of the SLC26A2 protein. The c.1375_1377dup(p.Val459dup) variant identified in clinically milder atelosteogenesis type II-diastrophic dysplasia spectrum lethal phenotype is predicted to decrease the Qualitative Model Energy Analysis (QMean), which affects major geometrical aspects of the SLC26A2 protein structure. CONCLUSION: We expand the spectrum of SLC26A2 related lethal chondrodysplasia and report three novel variants correlating clinical severity and protein phenotype within the lethal spectrum of this rare dysplasia. We demonstrate the relevance of structural characterization to aid novel variant reclassification to provide better prenatal management and reproductive options to families with lethal antenatal skeletal disorder.

Extreme Genu Recurvatum Deformity in a Pediatric Patient With Spondyloepiphyseal Dysplasia: Gradual Correction With Z-plates and Hexapod Frame.

Spondyloepiphyseal dysplasia is a type II collagenopathy with resulting spinal and extremity deformities. The clinical manifestations include short stature, hearing loss, kyphoscoliosis, and complex knee deformities. Genu recurvatum can be a challenging surgical problem, especially when the deformity is severe. In this report, we present a case of severe genu recurvatum in a 14-year-old female that was treated with a pediatric circular fixator with the addition of two z-plates. At one year follow-up, the patient demonstrated improved knee range of motion, tibial alignment with the radiographic union, and good ambulatory ability. The hexapod fixator with the use of two Z-plates may help ensure that appropriate ring strut angles are achieved. Larger studies regarding the efficacy of this treatment option in spondyloepiphyseal dysplasia are required.

Early Gestational Diagnosis of Lethal Skeletal Dysplasias: A 15 Year Retrospective Cohort Reviewing Concordance between Ultrasonographic, Genetic and Morphological Features.

Aim: We evaluated the diagnostic accuracy of ultrasound, postmortem and genetic studies in classifying skeletal dysplasias in the first vs second trimester of pregnancy. Methods: We retrospectively gathered data from a 15 year period of all the prenatal ultrasounds, autopsies, and available genetic studies on fetuses with skeletal dysplasias from our institution. Results: Five (23%) and 17 (77%) fetuses were diagnosed during the first and second trimester of pregnancy respectively. Only partial characterization was possible with ultrasound in the first trimester. Complete characterization was established in five cases (30%) in the second trimester with ultrasound alone. Pathology provided an additional diagnostic yield of 40% and 47% and genetics an additional 40% and 11% in the first and second trimesters respectively. Conclusion: Ultrasound is an effective screening but not a diagnostic tool. Complete characterizations of dysplasia increased from 22% by ultrasound alone to 86% with pathology and genetics.

Progressive pseudorheumatoid dysplasia: A rare entity mimicking juvenile idiopathic arthritis.

Progressive pseudorheumatoid dysplasia can be confused with juvenile idiopathic arthritis. Treatment is mainly symptomatic and the prescription of immunosupressive agents is unnecessary. Surgery may be indicated at advanced stages of the disease.

Imaging studies used as aid in the diagnosis of cleidocranial dysplasia. A review / Estudios de imagen utilizados como ayuda en el diagnóstico de displasia cleidocraneal. Una revisión

Cleidocranial dysplasia (CCD), also known as Marie-Sainton syndrome, is a rare disorder of autosomal dominant type that presents specific characteristics at the skeletal and dental level. The diagnosis of CCD is based on clinical and radiographic findings. Panoramic, cephalometric and anterior poster radiographs have been used for its diagnosis in dentistry. However, these radiological techniques have limitations, and advances in technology with new imaging studies such as magnetic resonance imaging (MRI) and ultrasound have emerged, contributing to the diagnosis of CCD. Therefore, the aim of this review was to identify and describe current imaging studies that contribute to both the diagnosis and adequate and efficient treatment planning of CCD, and describe the clinical and radiographic characteristics of patients with this syndrome. (AU)

La displasia cleidocraneal (DCC), también conocida como síndrome de Marie-Sainton, es un trastorno poco común de tipo autosómico dominante, que presenta características específicas a nivel esquelético y dental. El diagnóstico de DCC se basa en hallazgos clínicos y radiográficos. Las radiografías panorámicas, cefalométricas y posteroanteriores se han utilizado para su diagnóstico en el área de la odontología, pero con los avances de la tecnología y debido a las limitaciones de estas técnicas radiológicas han surgido nuevos estudios de imagen como la resonancia magnética (RM) y la ecografía, que contribuyen al diagnóstico de DCC. Por lo tanto, el propósito de esta revisión fue identificar y describir los estudios de imagen actuales que aportan tanto al diagnóstico como a la planificación del tratamiento adecuado y eficiente de la DCC, y permiten describir las características clínicas y radiográficas de los pacientes con este síndrome. (AU)

Molecular diagnosis for 55 fetuses with skeletal dysplasias by whole-exome sequencing: A retrospective cohort study.

Skeletal dysplasias (SDs) are common birth defects, but they are difficult to diagnose accurately according to only the limited phenotypic information available from ultrasound during the pregnancy. To evaluate the application of whole-exome sequencing (WES) and expand the data in the prenatal molecular diagnosis of fetuses with SDs, we collected 55 fetuses with SDs based on ultrasonographic features. WES of the fetuses or parent-fetus trio were subjected to sequential tests and produced a diagnostic yield of 64% (35/55). 65% (11/17) of families with a history of adverse pregnancies were diagnosed, 16 genes were involved and 37 different pathogenic or likely pathogenic variants were identified, including 14 novel variants, which were first reported in this study. De novo variants were identified in 21 cases (60%, 21/35) among the fetuses with a genetic diagnosis. The pathogenicity of two novel splice-site variants was confirmed by constructing minigene in vitro. Our results revealed that WES can provide new evidence for the relationship between the genotype and phenotype of fetuses with SDs, as well as broaden the mutation spectrum of detected genes, which is significant for prenatal diagnosis and genetic counseling.

[Rare bone disorders and respective treatments]. / Seltene osteologische Erkrankungen und ihre Therapie.

Delineating the genetic background and the underlying pathophysiology of rare skeletal dysplasias enables a broader understanding of these disorders as well as novel perspectives regarding differential diagnosis and targeted development of therapeutic approaches. Hypophosphatasia (HPP) due to genetically determined Alkaline Phosphatase deficiency exemplifies this development. While an enzyme replacement therapy could be established for severe HPP with the prevailing bone manifestation, the clinical impact of not immediately bone-related manifestations just being successively understood. Correspondingly, the elucidation of the pathophysiology underlying renal phosphate wasting expanded our knowledge regarding phosphate metabolism and bone health and facilitated the development of an anti-FGF-23 Antibody for targeted treatment of X­linked Hypophosphatemia (XLH). Evolutions regarding the nosology of osteogenesis imperfecta (OI) along with the identification of further causative genes also detected in the context of genetically determined osteoporosis illustrate the pathophysiologic interrelation between monogenetic bone dysplasias and multifactorial osteoporosis. While current therapeutic strategies for OI follow osteoporosis treatment, the expanding knowledge about OI forms the fundament for establishing improved treatment strategies-for both OI and osteoporosis. Similar developments are emerging regarding rare skeletal disorders like Achondroplasia, Fibrodysplasia ossificans progressive and Morbus Morquio (Mukopolysaccharidosis Type IV).

Imaging studies used as aid in the diagnosis of cleidocranial dysplasia. A review.

Cleidocranial dysplasia (CCD), also known as Marie-Sainton syndrome, is a rare disorder of autosomal dominant type that presents specific characteristics at the skeletal and dental level. The diagnosis of CCD is based on clinical and radiographic findings. Panoramic, cephalometric and anterior poster radiographs have been used for its diagnosis in dentistry. However, these radiological techniques have limitations, and advances in technology with new imaging studies such as magnetic resonance imaging (MRI) and ultrasound have emerged, contributing to the diagnosis of CCD. Therefore, the aim of this review was to identify and describe current imaging studies that contribute to both the diagnosis and adequate and efficient treatment planning of CCD, and describe the clinical and radiographic characteristics of patients with this syndrome.

La displasia cleidocraneal (DCC), también conocida como síndrome de Marie-Sainton, es un trastorno poco común de tipo autosómico dominante, que presenta características específicas a nivel esquelético y dental. El diagnóstico de DCC se basa en hallazgos clínicos y radiográficos. Las radiografías panorámicas, cefalométricas y posteroanteriores se han utilizado para su diagnóstico en el área de la odontología, pero con los avances de la tecnología y debido a las limitaciones de estas técnicas radiológicas han surgido nuevos estudios de imagen como la resonancia magnética (RM) y la ecografía, que contribuyen al diagnóstico de DCC. Por lo tanto, el propósito de esta revisión fue identificar y describir los estudios de imagen actuales que aportan tanto al diagnóstico como a la planificación del tratamiento adecuado y eficiente de la DCC, y permiten describir las características clínicas y radiográficas de los pacientes con este síndrome.

Genetics for paediatric radiologists.

An understanding of genetics and genomics is increasingly important for all clinicians. Next-generation genomic sequencing technologies enable sequencing of the entire human genome in short timescales, and are increasingly being implemented in health care systems. Clinicians across all medical specialties will increasingly use results generated from genomic testing to inform their clinical practice and provide the best quality of care for patients. These innovations are already transforming the diagnostic pathways for rare genetic diseases, including skeletal dysplasias, with an inevitable impact on the traditional roles of diagnosticians. This article covers the fundamentals of human genetics, mechanisms of genetic variation and the technologies used to investigate the genetic basis of disease, with a specific focus on skeletal dysplasias and the potential impact of genomics on paediatric radiology.

Skeletal dysplasias in Latin America.

Skeletal dysplasias (SD) are disturbances in growth due to defects intrinsic to the bone and/or cartilage, usually affecting multiple bones and having a progressive character. In this article, we review the state of clinical and research SD resources available in Latin America, including three specific countries (Brazil, Argentina, and Chile), that have established multidisciplinary clinics for the care of these patients. From the epidemiological point of view, the SD prevalence of 3.2 per 10,000 births from nine South American countries included in the ECLAMC network represents the most accurate estimate not just in Latin America, but worldwide. In Brazil, there are currently five groups focused on SD. The data from one of these groups including the website www.ocd.med.br, created to assist in the diagnosis of SD, are highlighted showing that telemedicine for this purpose represents a good strategy for the region. The experience of more than 30 years of the SD multidisciplinary clinic in an Argentinian Hospital is presented, evidencing a solid experience mainly in the follow-up of the most frequent SD, especially those belonging the FGFR3 group and OI. In Chile, a group with 20 years of experience presents its work with geneticists and pediatricians, focusing on diagnostic purposes and clinical management. Altogether, although SD health-care and research activities in Latin America are in their early stages, the experience in these three countries seems promising and stimulating for the region as a whole.

Prenatal diagnosis of skeletal dysplasias using whole exome sequencing in China.

BACKGROUND: Skeletal dysplasias account for nearly 10% of fetal structural malformations detected by ultrasonography. This clinically heterogeneous group of genetic anomaly includes at least 461 genetic skeletal disorders with extreme clinical, phenotypic, and genetic heterogeneities, thus, significantly complicates accurate diagnosis. Researches have used whole exome sequencing (WES) for prenatal molecular diagnoses of skeletal dysplasias, however, data are still limited. METHODS: DNA extracted from umbilical cord blood or amniocytes from fetuses suspected of skeletal dysplasias based on ultrasound evaluations were analyzed by WES. Blood samples were taken from the parents of the positive fetuses for co-segregation analysis using Sanger sequencing. RESULT: Definitive molecular diagnosis was made in 6/8 (75%) cases, comprised of 5 de novo disease-causing changes in 3 genes (FGFR3, COL2A1, and COL1A2) and one proband with a biallelic deficiency for Lamin B Receptor(LBR),and including 3 novel variants. All fetuses had no detectable copy number variation (CNV) from sequencing results. CONCLUSIONS: Our study suggests that WES is an efficient approach for prenatal diagnosis of fetuses suspected of skeletal abnormalities and contributes to parental genetics counseling and pregnancy management.

WNT Signaling and Bone: Lessons From Skeletal Dysplasias and Disorders.

Skeletal dysplasias are a diverse group of heritable diseases affecting bone and cartilage growth. Throughout the years, the molecular defect underlying many of the diseases has been identified. These identifications led to novel insights in the mechanisms regulating bone and cartilage growth and homeostasis. One of the pathways that is clearly important during skeletal development and bone homeostasis is the Wingless and int-1 (WNT) signaling pathway. So far, three different WNT signaling pathways have been described, which are all activated by binding of the WNT ligands to the Frizzled (FZD) receptors. In this review, we discuss the skeletal disorders that are included in the latest nosology of skeletal disorders and that are caused by genetic defects involving the WNT signaling pathway. The number of skeletal disorders caused by defects in WNT signaling genes and the clinical phenotype associated with these disorders illustrate the importance of the WNT signaling pathway during skeletal development as well as later on in life to maintain bone mass. The knowledge gained through the identification of the genes underlying these monogenic conditions is used for the identification of novel therapeutic targets. For example, the genes underlying disorders with altered bone mass are all involved in the canonical WNT signaling pathway. Consequently, targeting this pathway is one of the major strategies to increase bone mass in patients with osteoporosis. In addition to increasing the insights in the pathways regulating skeletal development and bone homeostasis, knowledge of rare skeletal dysplasias can also be used to predict possible adverse effects of these novel drug targets. Therefore, this review gives an overview of the skeletal and extra-skeletal phenotype of the different skeletal disorders linked to the WNT signaling pathway.

FGF23-Related Hypophosphataemic Bone Disease.

Metabolic skeletal dysplasias comprise an extensive group of diseases capable of causing changes, usually progressive, in the bone and are due to hereditary disorders in many cases. The diagnosis and treatment of these diseases are not without difficulty, both because of their rarity and their possible confusion with more common diseases. A paradigmatic case of these metabolic skeletal dysplasias is X-linked hypophosphataemic rickets, which causes phosphaturia, a condition that alters the phosphate-calcium metabolism balance consequently causing, among other conditions, skeletal deformities and short stature. The genetic advances in recent years allow a much more accurate diagnosis of this disease when suspected, making differential diagnosis easier with similar entities but whose real causes are different. A better understanding of the phosphate-calcium metabolism allows us to replace the symptomatic treatment currently available with one that involves rebalancing the excess of fibroblast growth factor 23 (FGF23) by using monoclonal antibodies. In November 2018, a symposium sponsored by Kyowa Kirin Pharmaceuticals took place in Madrid, in which national and international experts addressed several aspects of these rare kidney diseases. Some topics addressed were the present and future genetic diagnosis, the use of multi-gene panels in renal or skeletal diseases, the role of animal models to better understand underlying skeletal changes, and the role of conventional radiology and surgery in the diagnosis and final treatment of bone deformities; all these without forgetting the important role of FGF23 and Klotho imbalances that result in the genetic change causing this disease. The optimization and limitations of conventional treatments currently available was also a topic addressed extensively, as well as the implications that new treatments against FGF23 could have in the future. This article is based on previously conducted studies and does not contain any new studies with human participants or animals performed by the author.

Massively Parallel Sequencing for Rare Genetic Disorders: Potential and Pitfalls.

There have been two major eras in the history of gene discovery. The first was the era of linkage analysis, with approximately 1,300 disease-related genes identified by positional cloning by the turn of the millennium. The second era has been powered by two major breakthroughs: the publication of the human genome and the development of massively parallel sequencing (MPS). MPS has greatly accelerated disease gene identification, such that disease genes that would have taken years to map previously can now be determined in a matter of weeks. Additionally, the number of affected families needed to map a causative gene and the size of such families have fallen: de novo mutations, previously intractable by linkage analysis, can be identified through sequencing of the parent-child trio, and genes for recessive disease can be identified through MPS even of a single affected individual. MPS technologies include whole exome sequencing (WES), whole genome sequencing (WGS), and panel sequencing, each with their strengths. While WES has been responsible for most gene discoveries through MPS, WGS is superior in detecting copy number variants, chromosomal rearrangements, and repeat-rich regions. Panels are commonly used for diagnostic purposes as they are extremely cost-effective and generate manageable quantities of data, with no risk of unexpected findings. However, in instances of diagnostic uncertainty, it can be challenging to choose the right panel, and in these circumstances WES has a higher diagnostic yield. MPS has ethical, social, and legal implications, many of which are common to genetic testing generally but amplified due to the magnitude of data (e.g., relationship misattribution, identification of variants of uncertain significance, and genetic discrimination); others are unique to WES and WGS technologies (e.g., incidental or secondary findings). Nonetheless, MPS is rapidly translating into clinical practice as an extremely useful part of the clinical armamentarium.