Prenatal presentation of a rare genetic disorder: a clinical, autopsy and molecular correlation

Walker Warburg syndrome (WWS) lies at the severe end of the spectrum of the congenital muscular dystrophies. WWS is a congenital disorder of the O-glycosylation that disrupts in the post-translation modification of dystroglycan proteins. WWS is characterized by the involvement of the central nervous system and rarely by multisystem involvement. Next-generation sequencing discovered that multiple genes are associated with this disorder. FKTN is the rarest cause of WWS. We describe a clinical-autopsy report of a molecularly- confirmed WWS case presenting with ventriculomegaly, agenesis of the corpus callosum with a novel phenotype of Dandy-Walker malformation and unilateral multi-cystic kidney. The whole-exome sequencing confirmed a homozygous variant (c.411C>A) in the FKTN gene with a premature termination codon. This case emphasizes the importance of detailed postnatal phenotyping through an autopsy in any pregnancy with antenatally identified malformations. Obstetricians, pediatricians as well as fetal medicine experts need to counsel the parents and focus on preserving the appropriate sample for genetic testing. WWS, though rare deserves testing especially in the presence of positive family history. Dandy-Walker malformation is a novel feature and expands the phenotypic spectrum

Elucidation of the phenotypic spectrum and genetic landscape in primary and secondary microcephaly

Purpose: Microcephaly is a sign of many genetic conditions but has been rarely systematically evaluated. We therefore comprehensively studied the clinical and genetic landscape of an unselected cohort of patients with microcephaly. Methods: We performed clinical assessment, high-resolution chromosomal microarray analysis, exome sequencing, and functional studies in 62 patients (58% with primary microcephaly [PM], 27% with secondary microcephaly [SM], and 15% of unknown onset). Results: We found severity of developmental delay/intellectual disability correlating with severity of microcephaly in PM, but not SM. We detected causative variants in 48.4% of patients and found divergent inheritance and variant pattern for PM (mainly recessive and likely gene-disrupting [LGD]) versus SM (all dominant de novo and evenly LGD or missense). While centrosome-related pathways were solely identified in PM, transcriptional regulation was the most frequently affected pathway in both SM and PM. Unexpectedly, we found causative variants in different mitochondria-related genes accounting for ~5% of patients, which emphasizes their role even in syndromic PM. Additionally, we delineated novel candidate genes involved in centrosome-related pathway (SPAG5, TEDC1), Wnt signaling (VPS26A, ZNRF3), and RNA trafficking (DDX1). Conclusion: Our findings enable improved evaluation and genetic counseling of PM and SM patients and further elucidate microcephaly pathways

Undiagnosed diseases: Needs and opportunities in 20 countries participating in the Undiagnosed Diseases Network International

Introduction: Rare diseases (RD) are a health priority worldwide, overall affecting hundreds of millions of people globally. Early and accurate diagnosis is essential to support clinical care but remains challenging in many countries, especially the low- and medium-income ones. Hence, undiagnosed RD (URD) account for a significant portion of the overall RD burden. Methods: In October 2020, the Developing Nations Working Group of the Undiagnosed Diseases Network International (DNWG-UDNI) launched a survey among its members, belonging to 20 countries across all continents, to map unmet needs and opportunities for patients with URD. The survey was based on questions with open answers and included eight different domains. Conflicting interpretations were resolved in contact with the partners involved. Results: All members responded to the survey. The results indicated that the scientific and medical centers make substantial efforts to respond to the unmet needs of patients. In most countries, there is a high awareness of RD issues. Scarcity of resources was highlighted as a major problem, leading to reduced availability of diagnostic expertise and research. Serious equity in accessibility to services were highlighted both within and between participating countries. Regulatory problems, including securing informed consent, difficulties in sending DNA to foreign laboratories, protection of intellectual property, and conflicts of interest on the part of service providers, remain issues of concern. Finally, most respondents stressed the need to strengthen international cooperation in terms of data sharing, clinical research, and diagnostic expertise for URD patients in low and medium income countries. Discussion: The survey highlighted that many countries experienced a discrepancy between the growing expertise and scientific value, the level of awareness and commitment on the part of relevant parties, and funding bodies. Country-tailored public health actions, including general syllabus of medical schools and of the education of other health professionals, are needed to reduce such gaps.VSh is supported by Health Systems Research Institute of Thailand (65-040). SJ is supported by National Medical Research Council, Singapore (Grants ID CSAINV21jun-0003 and CIRG22jul-0003).S

Unmet needs in countries participating in the undiagnosed diseases network international: an international survey considering national health care and economic indicators

BackgroundPatients, families, the healthcare system, and society as a whole are all significantly impacted by rare diseases (RDs). According to various classifications, there are currently up to 9,000 different rare diseases that have been recognized, and new diseases are discovered every month. Although very few people are affected by each uncommon disease individually, millions of people are thought to be impacted globally when all these conditions are considered. Therefore, RDs represent an important public health concern. Although crucial for clinical care, early and correct diagnosis is still difficult to achieve in many nations, especially those with low and middle incomes. Consequently, a sizeable amount of the overall burden of RD is attributable to undiagnosed RD (URD). Existing barriers and policy aspects impacting the care of patients with RD and URD remain to be investigated.MethodsTo identify unmet needs and opportunities for patients with URD, the Developing Nations Working Group of the Undiagnosed Diseases Network International (DNWG-UDNI) conducted a survey among its members, who were from 20 different nations. The survey used a mix of multiple choice and dedicated open questions covering a variety of topics. To explore reported needs and analyze them in relation to national healthcare economical aspects, publicly available data on (a) World Bank ranking; (b) Current health expenditure per capita; (c) GDP per capita; (d) Domestic general government health expenditure (% of GDP); and (e) Life expectancy at birth, total (years) were incorporated in our study.ResultsThis study provides an in-depth evaluation of the unmet needs for 20 countries: low-income (3), middle-income (10), and high-income (7). When analyzing reported unmet needs, almost all countries (N = 19) indicated that major barriers still exist when attempting to improve the care of patients with UR and/or URD; most countries report unmet needs related to the availability of specialized care and dedicated facilities. However, while the countries ranked as low income by the World Bank showed the highest prevalence of referred unmet needs across the different domains, no specific trend appeared when comparing the high, upper, and low-middle income nations. No overt trend was observed when separating countries by current health expenditure per capita, GDP per capita, domestic general government health expenditure (% of GDP) and life expectancy at birth, total (years). Conversely, both the GDP and domestic general government health expenditure for each country impacted the presence of ongoing research.ConclusionWe found that policy characteristics varied greatly with the type of health system and country. No overall pattern in terms of referral for unmet needs when separating countries by main economic or health indicators were observed. Our findings highlight the importance of identifying actionable points (e.g., implemented orphan drug acts or registries where not available) in order to improve the care and diagnosis of RDs and URDs on a global scale

Implications of CYP21A2 gene duplications in carrier screening and prenatal diagnosis of congenital adrenal hyperplasia due to 21 Hydroxylase deficiency

Background: Congenital adrenal hyperplasia (CAH) is an autosomal recessive disorder that presents as salt wasting or simple virilization (SV). It is due to biallelic mutations in the CYP21A2 gene that encodes the 21-hydroxylase enzyme. This gene is susceptible to deletions and duplications due to the presence of a homologous pseudogene and its location in the RCCX module. This complicates the interpretation of molecular analysis of the CYP21A2 gene. Clinical Description: During preconception counseling and subsequent workup of a couple, the wife (who had been diagnosed with simple virilizing CAH at the age of 14 years, based on clinical and metabolic profile) was identified with c.373C >T variant on one and a deletion on the other allele of CYP21A2. Her asymptomatic husband harbored a novel c. 939+5G>A variant in intron 7 of CYP21A2. Prenatal diagnosis by Sanger sequencing revealed the presence of both maternal (c.373C>T) and paternal (c. 939+5G>A) variants in the fetus, indicative of SV form. After genetic counseling, the parents decided to continue with the pregnancy. Management and Outcome: A baby boy was born who underwent investigations according to the standard protocol. However, a diagnosis of CAH could not be established conclusively. The molecular diagnosis of both baby and parents was revisited. It was found that the baby harbored a duplication of CYP21A2 (inherited from his father) along with a novel variant. The duplication neutralized the paternal variant, and thus the baby was not affected, but a carrier. Conclusion: Evaluation of duplication in parents is crucial before prenatal testing, as duplications have important bearing on the carrier status

Unclassified sudden infant death due to congenital long QT syndrome with TRPM4 mutation

Background: Congenital long QT syndrome (cLQTS) are heritable disorders due to genetic mutations causing prolonged corrected QT (QTc) interval that may result in fatal arrhythmias. Clinical Description: A well 20-day-old, exclusively breastfed boy had an episode of unresponsiveness with no other symptoms. There was a history of four previous unexplained infantile deaths after similar complaints. General and systemic examination was normal. The differential diagnoses were neonatal apnea, seizures, and inborn errors of metabolism. Management: Sepsis, hypoglycemia, and electrolyte imbalance were ruled out. Electrocardiography (ECG), chest radiograph, and echocardiograph were normal. Ultrasonogram of the cranium ruled out structural abnormality and bleed. Electroencephalogram was normal. First-line metabolic investigations were normal. On day 28 of life, he had a recurrent episode of apnea. ECG evaluation during this episode revealed a prolonged QTc interval. Suspecting cLQTS, Trio Whole Exome Sequencing for mutations in the cLQTS susceptibility genes was performed in the proband and parents. A heterozygous variation, c.290C>T; p.Thr97Met in TRPM4 was identified in the symptomatic neonate and asymptomatic mother, suggesting autosomal dominant inheritance. The baby was started on oral propranolol, but succumbed at 8 weeks. The mother was referred for cardiac management and parents counseled about possible prenatal diagnosis in subsequent pregnancies. Conclusion: cLQTS should be suspected in neonatal apnea, when no other cause is appreciable. A normal ECG does not exclude cLQTS. If there is a strong suspicion, repeat ECGs and appropriate genetic testing should be done. Patients should be managed according to standard guidelines

Molecular evaluation of a novel missense mutation & an insertional truncating mutation in SUMF1 gene

Background & objectives: Multiple suphphatase deficiency (MSD) is an autosomal recessive disorder affecting the post translational activation of all enzymes of the sulphatase family. To date, approximately 30 different mutations have been identified in the causative gene, sulfatase modifying factor 1 (SUMF1). We describe here the mutation analysis of a case of MSD. Methods: The proband was a four year old boy with developmental delay followed by neuroregression. He had coarse facies, appendicular hypertonia, truncal ataxia and ichthyosis limited to both lower limbs. Radiographs showed dysostosis multiplex. Clinical suspicion of MSD was confirmed by enzyme analysis of four enzymes of the sulphatase group. Results: The patient was compound heterozygote for a c.451A>G (p.K151E) substitution in exon 3 and a single base insertion mutation (c.690_691 InsT) in exon 5 in the SUMF1 gene. The bioinformatic analysis of the missense mutation revealed no apparent effect on the overall structure. However, the mutated 151-amino acid residue was found to be adjacent to the substrate binding and the active site residues, thereby affecting the substrate binding and/or catalytic activity, resulting in almost complete loss of enzyme function. Conclusions: The two mutations identified in the present case were novel. This is perhaps the first report of an insertion mutation in SUMF1 causing premature truncation of the protein

Mutation–proved Clouston syndrome in a large Indian family with a variant phenotype

Hereditary ectodermal dysplasias, a group of disorders affecting skin, hair, nails, and teeth, consist of two main clinical forms – hypohidrotic and hidrotic. Clouston syndrome is a hidrotic ectodermal dysplasia characterized by a triad of generalized hypotrichosis, palmoplantar hyperkeratosis, and nail dystrophy. This paper reports a large Indian family with Clouston syndrome but with the absence of palmoplantar keratoderma, one of the features of the typical triad, thus representing phenotypic heterogeneity, in spite of the presence of a common known mutation in GJB6 gene (p.Gly11Arg)

Urea cycle disorders in India: clinical course, biochemical and genetic investigations, and prenatal testing

Abstract Background Urea cycle disorders (UCDs) are inherited metabolic disorders that present with hyperammonemia, and cause significant mortality and morbidity in infants and children. These disorders are not well reported in the Indian population, due to lack of a thorough study of the clinical and molecular profile. Results We present data from two major metabolic centres in India, including 123 cases of various UCDs. The majority of them (72/123, 58%) presented in the neonatal period (before 30 days of age) with 88% on or before day 7 of life (classical presentation), and had a high mortality (64/72, 88%). Citrullinemia type 1 was the most common UCD, observed in 61/123 patients. Ornithine transcarbamylase (OTC) deficiency was the next most common, seen in 24 cases. Argininosuccinic aciduria was diagnosed in 20 cases. Deficiencies of arginase, N-acetylglutamate synthase, carbamoyl phosphate synthetase, citrin, and lysinuric protein intolerance were also observed. Molecular genetic analysis revealed two common ASS1 mutations: c.470G > A (p.Arg157His) and c.1168G > A (p.Gly390Arg) (36 of 55 tested patients). In addition, few recurrent point mutations in ASL gene, and a deletion of the whole OTC gene were also noted. A total of 24 novel mutations were observed in the various genes studied. We observed a poor clinical outcome with an overall all time mortality of 63% (70/110 cases with a known follow-up), and disability in 70% (28/40) among the survivors. Prenatal diagnosis was performed in 30 pregnancies in 25 families, including one pre-implantation genetic diagnosis. Conclusions We report the occurrence of UCDs in India and the spectrum that may be different from the rest of the world. Citrullinemia type 1 was the most common UCD observed in the cohort. Increasing awareness amongst clinicians will improve outcomes through early diagnosis and timely treatment. Genetic diagnosis in the proband will enable prenatal/pre-implantation diagnosis in subsequent pregnancies