Actionability of unanticipated monogenic disease risks in newborn genomic screening: Findings from the BabySeq Project.

Newborn genomic sequencing (NBSeq) to screen for medically important genetic information is of considerable interest but data characterizing the actionability of such findings, and the downstream medical efforts in response to discovery of unanticipated genetic risk variants, are lacking. From a clinical trial of comprehensive exome sequencing in 127 apparently healthy infants and 32 infants in intensive care, we previously identified 17 infants (10.7%) with unanticipated monogenic disease risks (uMDRs). In this analysis, we assessed actionability for each of these uMDRs with a modified ClinGen actionability semiquantitative metric (CASQM) and created radar plots representing degrees of penetrance of the condition, severity of the condition, effectiveness of intervention, and tolerability of intervention. In addition, we followed each of these infants for 3-5 years after disclosure and tracked the medical actions prompted by these findings. All 17 uMDR findings were scored as moderately or highly actionable on the CASQM (mean 9, range: 7-11 on a 0-12 scale) and several distinctive visual patterns emerged on the radar plots. In three infants, uMDRs revealed unsuspected genetic etiologies for existing phenotypes, and in the remaining 14 infants, uMDRs provided risk stratification for future medical surveillance. In 13 infants, uMDRs prompted screening for at-risk family members, three of whom underwent cancer-risk-reducing surgeries. Although assessments of clinical utility and cost-effectiveness will require larger datasets, these findings suggest that large-scale comprehensive sequencing of newborns will reveal numerous actionable uMDRs and precipitate substantial, and in some cases lifesaving, downstream medical care in newborns and their family members.

A genome sequencing system for universal newborn screening, diagnosis, and precision medicine for severe genetic diseases.

Newborn screening (NBS) dramatically improves outcomes in severe childhood disorders by treatment before symptom onset. In many genetic diseases, however, outcomes remain poor because NBS has lagged behind drug development. Rapid whole-genome sequencing (rWGS) is attractive for comprehensive NBS because it concomitantly examines almost all genetic diseases and is gaining acceptance for genetic disease diagnosis in ill newborns. We describe prototypic methods for scalable, parentally consented, feedback-informed NBS and diagnosis of genetic diseases by rWGS and virtual, acute management guidance (NBS-rWGS). Using established criteria and the Delphi method, we reviewed 457 genetic diseases for NBS-rWGS, retaining 388 (85%) with effective treatments. Simulated NBS-rWGS in 454,707 UK Biobank subjects with 29,865 pathogenic or likely pathogenic variants associated with 388 disorders had a true negative rate (specificity) of 99.7% following root cause analysis. In 2,208 critically ill children with suspected genetic disorders and 2,168 of their parents, simulated NBS-rWGS for 388 disorders identified 104 (87%) of 119 diagnoses previously made by rWGS and 15 findings not previously reported (NBS-rWGS negative predictive value 99.6%, true positive rate [sensitivity] 88.8%). Retrospective NBS-rWGS diagnosed 15 children with disorders that had been undetected by conventional NBS. In 43 of the 104 children, had NBS-rWGS-based interventions been started on day of life 5, the Delphi consensus was that symptoms could have been avoided completely in seven critically ill children, mostly in 21, and partially in 13. We invite groups worldwide to refine these NBS-rWGS conditions and join us to prospectively examine clinical utility and cost effectiveness.

New ASH initiatives to improve patient care in the long-overlooked sickle cell disease.

Because of the unique biology of sickle cell disease (SCD) as well as the societal disadvantages and racial inequities suffered by these patients, individuals with SCD have not benefited from the same remarkable advances in care and therapeutics as those with other hematologic disorders. Life expectancy of individuals with SCD is shortened by ∼20 years even with optimal clinical care, and infant mortality continues to be a major concern in low-income countries. As hematologists, we must do more. The American Society of Hematology (ASH) and the ASH Research Collaborative have instituted a multipronged initiative to improve the lives of individuals living with this disease. Here, we describe 2 components of this ASH initiative, the Consortium on Newborn Screening in Africa (CONSA) to improve the early diagnosis of infants in low-resource countries and the SCD Clinical Trial Network to accelerate the development of more effective therapeutics and care for those with this disorder. The combination of SCD-focused initiatives, ASH Research Collaborative, CONSA, and Sickle Cell Clinical Trials Network has enormous potential to dramatically alter the course of SCD worldwide. We believe that the timing is ripe to embark on these critical and worthwhile initiatives and improve the lives of individuals with this disease.

Australian public perspectives on genomic newborn screening: which conditions should be included?

BACKGROUND: Implementing genomic sequencing into newborn screening programs allows for significant expansion in the number and scope of conditions detected. We sought to explore public preferences and perspectives on which conditions to include in genomic newborn screening (gNBS). METHODS: We recruited English-speaking members of the Australian public over 18 years of age, using social media, and invited them to participate in online focus groups. RESULTS: Seventy-five members of the public aged 23-72 participated in one of fifteen focus groups. Participants agreed that if prioritisation of conditions was necessary, childhood-onset conditions were more important to include than later-onset conditions. Despite the purpose of the focus groups being to elicit public preferences, participants wanted to defer to others, such as health professionals or those with a lived experience of each condition, to make decisions about which conditions to include. Many participants saw benefit in including conditions with no available treatment. Participants agreed that gNBS should be fully publicly funded. CONCLUSION: How many and which conditions are included in a gNBS program will be a complex decision requiring detailed assessment of benefits and costs alongside public and professional engagement. Our study provides support for implementing gNBS for treatable childhood-onset conditions.

Estimates of congenital cytomegalovirus-attributable infant mortality in high-income countries: A review.

As many as 5%-10% of infants with symptomatic congenital cytomegalovirus (cCMV) disease, or 0.4%-0.8% of all liveborn infants with cCMV infection, die in early infancy in high-income countries. However, estimates are uncertain due to several potential biases that can result from data limitations and study designs. First, infants with cCMV infections who die prior to diagnosis, which usually occurs at 1-4 weeks after birth, may be excluded from both the count of deaths and the denominator of cCMV births, resulting in left truncation and immortal time biases. These 'biases' are features of the data and do not reflect bias on the part of researchers, but understanding the potential existence of threats to validity can help with interpretation of findings. Left truncation of infant deaths occurring prior to diagnosis of cCMV can result in understatement of the burden of infant deaths due to cCMV. Conversely, overestimation of infant deaths associated with symptomatic cCMV may occur in clinical case series owing to greater representation of relatively severely affected infants owing to ascertainment and referral biases. In this review, we summarise the characteristics of 26 studies that reported estimates of cCMV-associated infant deaths, including potential biases or limitations to which those estimates may have been subject. We discuss study designs whose implementation might generate improved estimates of infant deaths attributable to cCMV. More complete estimates of the overall public health impact of cCMV could inform current and future screening, prevention, and vaccine research.

Impact of newborn screening for SCID on the management of congenital athymia.

BACKGROUND: Newborn screening (NBS) programs for severe combined immunodeficiency facilitate early diagnosis of severe combined immunodeficiency and promote early treatment with hematopoietic stem cell transplantation, resulting in improved clinical outcomes. Infants with congenital athymia are also identified through NBS because of severe T-cell lymphopenia. With the expanding introduction of NBS programs, referrals of athymic patients for treatment with thymus transplantation have recently increased at Great Ormond Street Hospital (GOSH) (London, United Kingdom). OBJECTIVE: We studied the impact of NBS on timely diagnosis and treatment of athymic infants with thymus transplantation at GOSH. METHODS: We compared age at referral and complications between athymic infants diagnosed after clinical presentation (n = 25) and infants identified through NBS (n = 19) who were referred for thymus transplantation at GOSH between October 2019 and February 2023. We assessed whether age at time of treatment influences thymic output at 6 and 12 months after transplantation. RESULTS: The infants referred after identification through NBS were significantly younger and had fewer complications, in particular fewer infections. All deaths occurred in the group of those who did not undergo NBS, including 6 patients before and 2 after thymus transplantation because of preexisting infections. In the absence of significant comorbidities or diagnostic uncertainties, timely treatment was achieved more frequently after NBS. Treatment when younger than age 4 months was associated with higher thymic output at 6 and 12 months after transplantation. CONCLUSION: NBS contributes to earlier recognition of congenital athymia, promoting referral of athymic patients for thymus transplantation before they acquire infections or other complications and facilitating treatment at a younger age, thus playing an important role in improving their outcomes.

Newborn screening for lipid disorders.

PURPOSE OF REVIEW: Newborn screening is one of the most successful public health programs of the last century and offers unparalleled access to universal screening for a variety of metabolic and other disorders. Interest in development of newborn screening for lipid disorders has intensified in recent years. Screening newborns for lipid disorders has important implications for the health of the newborn as well as their relatives, and in the case of more common lipid disorders like familial hypercholesterolemia, could have important public health implications. RECENT FINDINGS: Recent studies have demonstrated feasibility of measuring biomarkers for heterozygous familial hypercholesterolemia from newborn screening dried blood spot specimens. Another lipid disorder, cerebrotendinous xanthomatosis, is currently amenable to newborn screening utilizing currently available assays. New research in next-generation sequencing as a primary screen in newborns will also identify both common and rare lipid disorders in newborns. SUMMARY: Historically, newborn screening for lipid disorders was not done for many reasons, but new research has developed testing methods that may successfully identify common and rare lipid disorders. This will impact the health of the newborn but could also impact family members and public health.

Plasma C24:0- and C26:0-lysophosphatidylcholines are reliable biomarkers for the diagnosis of peroxisomal ß-oxidation disorders.

The gold-standard diagnostic test for peroxisomal disorders (PDs) is plasma concentration analysis of very long-chain fatty acids (VLCFAs). However, this method's time-consuming nature and limitations in cases which present normal VLCFA levels necessitates alternative approaches. The analysis of C26:0-lysophosphatydylcholine (C26:0-LPC) in dried blood spot samples by tandem-mass spectrometry (MS/MS) has successfully been implemented in certain newborn screening programs to diagnose X-linked adrenoleukodystrophy (ALD). However, the diagnostic potential of very long-chain LPCs concentrations in plasma remains poorly understood. This study sought to evaluate the diagnostic performance of C26:0-LPC and other very long-chain LPCs, comparing them to VLCFA analysis in plasma. The study, which included 330 individuals affected by a peroxisomal ß-oxidation deficiency and 407 control individuals, revealed that C26:0- and C24:0-LPC concentrations demonstrated the highest diagnostic accuracy (98.8% and 98.4%, respectively), outperforming VLCFA when C26:0/C22:0 and C24:0/C22:0 ratios were combined (98.1%). Combining C24:0- and C26:0-LPC gave the highest sensitivity (99.7%), with ALD females exhibiting notably higher sensitivity compared with the VLCFA ratio combination (98.7% vs. 93.5%, respectively). In contrast, C22:0-LPC exhibited suboptimal performance, primarily due to its low sensitivity (75%), but we identified a potential use to help distinguish between ALD and Zellweger spectrum disorders. In summary, MS/MS analysis of plasma C24:0- and C26:0-LPC concentrations represents a rapid and straightforward approach to diagnose PDs, demonstrating superior diagnostic accuracy, particularly in ALD females, compared with conventional VLCFA biomarkers. We strongly recommend integrating very-long chain LPC plasma analysis in the diagnostic evaluation of individuals suspected of having a PD.

Relevance of lymphocyte proliferation to PHA in severe combined immunodeficiency (SCID) and T cell lymphopenia.

Severe combined immunodeficiency (SCID) is characterized by a severe deficiency in T cell numbers. We analyzed data collected (n = 307) for PHA-based T cell proliferation from the PIDTC SCID protocol 6901, using either a radioactive or flow cytometry method. In comparing the two groups, a smaller number of the patients tested by flow cytometry had <10% of the lower limit of normal proliferation as compared to the radioactive method (p = 0.02). Further, in patients with CD3+ T cell counts between 51 and 300 cells/µL, there was a higher proliferative response with the PHA flow assay compared to the 3H-T assay (p < 0.0001), suggesting that the method of analysis influences the resolution and interpretation of PHA results. Importantly, we observed many SCID patients with profound T cell lymphopenia having normal T cell proliferation when assessed by flow cytometry. We recommend this test be considered only as supportive in the diagnosis of typical SCID.

Clinical Phenotypes of Cystic Fibrosis Carriers.

Cystic fibrosis (CF) is an autosomal recessive genetic disorder caused by mutations in CFTR, the cystic fibrosis transmembrane conductance regulator gene. People with CF experience a wide variety of medical conditions that affect the pulmonary, endocrine, gastrointestinal, pancreatic, biliary, and reproductive systems. Traditionally, CF carriers, with one defective copy of CFTR, were not thought to be at risk for CF-associated diseases. However, an emerging body of literature suggests that heterozygotes are at increased risk for many of the same conditions as homozygotes. For example, heterozygotes appear to be at increased risk for chronic pancreatitis, atypical mycobacterial infections, and bronchiectasis. In the United States alone, there are almost 10 million CF carriers. Universal newborn screening and prenatal genetic screening will identify more. Thus, there is a critical need to develop more precise estimates of health risks attributable to the CF carrier state across the lifespan.

Potential for a large-scale newborn screening strategy for sickle cell disease in Mali: A comparative diagnostic performance study of two rapid diagnostic tests (SickleScan® and HemotypeSC®) on cord blood.

Sickle cell disease (SCD) is a life-threatening disease requiring reliable early diagnosis. We assessed the acceptability and diagnostic performances of two rapid diagnostic tests (RDTs) to identify SCD (HbSS, HbSC, HbS/ß-thalassaemia) or SCD carrier (HbS/HbC) in a pilot SCD newborn screening (NBS) strategy in Mali. All consenting delivering women were offered SCD NBS using cord blood sampling on two RDTs (SickleScan® and HemotypeSC®) compared to the high-performance liquid chromatography (HPLC) gold standard to detect SCD states. From April 2021 to August 2021, 4333 delivering women were eligible of whom 96.1% were offered NBS: 1.6% refused, 13.8% delivered before consenting and 84.6% consented; 3648 newborns were diagnosed by HPLC; 1.64% had SCD (0.63% HbSS, 0.85% HbSC, 0.16 HbS/ß-plus-thalassaemia); 21.79% were SCD carrier. To detect accurately SCD, SickleScan® had a sensitivity of 81.67% (95% confidence interval [CI]: 71.88-91.46) and a negative predictive value (NPV) of 99.69% (95% CI: 99.51-99.87); HemotypeSC® had a sensitivity of 78.33% (95% CI: 67.91-88.76) and a NPV of 99.64% (95% CI: 99.44-99.83). To detect SCD carrier: SickleScan® sensitivity was 96.10% (95% CI: 94.75-97.45) and NPV, 98.90% (95% CI: 98.51-99.29); HemotypeSC® sensitivity was 95.22% (95% CI: 93.74-96.70) and NPV, 98.66% (95% CI: 98.24-99.03). Routine SCD NBS was acceptable. Compared with HPLC, both RDTs had reliable diagnostic performances to exclude SCD-free newborns and to identify SCD carriers to be further confirmed. This strategy could be implemented in large-scale NBS programmes.

Screening for haemoglobin disorders: One size may not fit all.

Accurate laboratory screening for sickle cell disease and other haemoglobin disorders is expanding worldwide. Two new reports describe different methods and strategies for screening in Mali and Denmark, respectively, and their encouraging results suggest that countries should tailor their screening programmes according to local needs, resources and opportunities. Commentary on: Guindo et al. Potential for a large-scale newborn screening strategy for sickle cell disease in Mali: a comparative diagnostic performance study of two rapid diagnostic tests (SickleScan® and HemotypeSC®) on cord blood. Br J Haematol 2024;204:337-345 and Gravholt et al. The Danish national haemoglobinopathy screening programme: report from 16 years of screening in a low-prevalence, non-endemic region. Br J Haematol 2024;204:329-336.

Congenital adrenal hyperplasia.

Congenital adrenal hyperplasia is a group of autosomal recessive disorders leading to multiple complex hormonal imbalances caused by various enzyme deficiencies in the adrenal steroidogenic pathway. The most common type of congenital adrenal hyperplasia is due to steroid 21-hydroxylase (21-OHase, henceforth 21OH) deficiency. The rare, classic (severe) form caused by 21OH deficiency is characterised by life-threatening adrenal crises and is the most common cause of atypical genitalia in neonates with 46,XX karyotype. After the introduction of life-saving hormone replacement therapy in the 1950s and neonatal screening programmes in many countries, nowadays neonatal survival rates in patients with congenital adrenal hyperplasia are high. However, disease-related mortality is increased and therapeutic management remains challenging, with multiple long-term complications related to treatment and disease affecting growth and development, metabolic and cardiovascular health, and fertility. Non-classic (mild) forms of congenital adrenal hyperplasia caused by 21OH deficiency are more common than the classic ones; they are detected clinically and primarily identified in female patients with hirsutism or impaired fertility. Novel treatment approaches are emerging with the aim of mimicking physiological circadian cortisol rhythm or to reduce adrenal hyperandrogenism independent of the suppressive effect of glucocorticoids.

Parental Engagement in Identifying Information Needs After Newborn Screening for Families of Infants with Suspected Athymia.

Congenital athymia is a rare T-lymphocytopaenic condition, which requires early corrective treatment with thymus transplantation (TT). Athymic patients are increasingly identified through newborn screening (NBS) for severe combined immunodeficiency (SCID). Lack of relatable information resources contributes to challenging patient and family journeys during the diagnostic period following abnormal NBS results. Patient and Public Involvement and Engagement (PPIE) activities, including parental involvement in paediatrics, are valuable initiatives to improve clinical communication and parental information strategies. Parents of infants with suspected athymia were therefore invited to discuss the information they received during the diagnostic period following NBS with the aim to identify parental information needs and targeted strategies to address these adequately. Parents reported that athymia was not considered with them as a possible differential diagnosis until weeks after initial NBS results. Whilst appropriate clinical information about athymia and TT was available upon referral to specialist immunology services, improved access to easy-to-understand information from reliable sources, including from clinical nurse specialists and peer support systems, remained desirable. A roadmap concept, with written or digital information, addressing parental needs in real time during a potentially complex diagnostic journey, was proposed and is transferrable to other inborn errors of immunity (IEI) and rare diseases. This PPIE activity provides insight into the information needs of parents of infants with suspected athymia who are identified through SCID NBS, and highlights the role for PPIE in promoting patient- and family-centred strategies to improve IEI care.

Measuring the effect of newborn screening on survival after haematopoietic cell transplantation for severe combined immunodeficiency: a 36-year longitudinal study from the Primary Immune Deficiency Treatment Consortium.

BACKGROUND: Severe combined immunodeficiency (SCID) is fatal unless durable adaptive immunity is established, most commonly through allogeneic haematopoietic cell transplantation (HCT). The Primary Immune Deficiency Treatment Consortium (PIDTC) explored factors affecting the survival of individuals with SCID over almost four decades, focusing on the effects of population-based newborn screening for SCID that was initiated in 2008 and expanded during 2010-18. METHODS: We analysed transplantation-related data from children with SCID treated at 34 PIDTC sites in the USA and Canada, using the calendar time intervals 1982-89, 1990-99, 2000-09, and 2010-18. Categorical variables were compared by χ2 test and continuous outcomes by the Kruskal-Wallis test. Overall survival was estimated by the Kaplan-Meier method. A multivariable analysis using Cox proportional hazards regression models examined risk factors for HCT outcomes, including the variables of time interval of HCT, infection status and age at HCT, trigger for diagnosis, SCID type and genotype, race and ethnicity of the patient, non-HLA-matched sibling donor type, graft type, GVHD prophylaxis, and conditioning intensity. FINDINGS: For 902 children with confirmed SCID, 5-year overall survival remained unchanged at 72%-73% for 28 years until 2010-18, when it increased to 87% (95% CI 82·1-90·6; n=268; p=0·0005). For children identified as having SCID by newborn screening since 2010, 5-year overall survival was 92·5% (95% CI 85·8-96·1), better than that of children identified by clinical illness or family history in the same interval (79·9% [69·5-87·0] and 85·4% [71·8-92·8], respectively [p=0·043]). Multivariable analysis demonstrated that the factors of active infection (hazard ratio [HR] 2·41, 95% CI 1·56-3·72; p<0·0001), age 3·5 months or older at HCT (2·12, 1·38-3·24; p=0·001), Black or African-American race (2·33, 1·56-3·46; p<0·0001), and certain SCID genotypes to be associated with lower overall survival during all time intervals. Moreover, after adjusting for several factors in this multivariable analysis, HCT after 2010 no longer conveyed a survival advantage over earlier time intervals studied (HR 0·73, 95% CI 0·43-1·26; p=0·097). This indicated that younger age and freedom from infections at HCT, both directly driven by newborn screening, were the main drivers for recent improvement in overall survival. INTERPRETATION: Population-based newborn screening has facilitated the identification of infants with SCID early in life, in turn leading to prompt HCT while avoiding infections. Public health programmes worldwide can benefit from this definitive demonstration of the value of newborn screening for SCID. FUNDING: National Institute of Allergy and Infectious Diseases, Office of Rare Diseases Research, and National Center for Advancing Translational Sciences.

Newborn Screening for Severe T and B Cell Lymphopenia Using TREC/KREC Detection: A Large-Scale Pilot Study of 202,908 Newborns.

Newborn screening (NBS) for severe inborn errors of immunity (IEI), affecting T lymphocytes, and implementing measurements of T cell receptor excision circles (TREC) has been shown to be effective in early diagnosis and improved prognosis of patients with these genetic disorders. Few studies conducted on smaller groups of newborns report results of NBS that also include measurement of kappa-deleting recombination excision circles (KREC) for IEI affecting B lymphocytes. A pilot NBS study utilizing TREC/KREC detection was conducted on 202,908 infants born in 8 regions of Russia over a 14-month period. One hundred thirty-four newborns (0.66‰) were NBS positive after the first test and subsequent retest, 41% of whom were born preterm. After lymphocyte subsets were assessed via flow cytometry, samples of 18 infants (0.09‰) were sent for whole exome sequencing. Confirmed genetic defects were consistent with autosomal recessive agammaglobulinemia in 1/18, severe combined immunodeficiency - in 7/18, 22q11.2DS syndrome - in 4/18, combined immunodeficiency - in 1/18 and trisomy 21 syndrome - in 1/18. Two patients in whom no genetic defect was found met criteria of (severe) combined immunodeficiency with syndromic features. Three patients appeared to have transient lymphopenia. Our findings demonstrate the value of implementing combined TREC/KREC NBS screening and inform the development of policies and guidelines for its integration into routine newborn screening programs.

Reducing Mortality and Morbidity in Children with Severe Combined Immunodeficiency in Switzerland: the Role of Newborn Screening.

Newborn screening (NBS) for severe combined immunodeficiency (SCID) has been introduced in various countries with the aim of reducing morbidity and mortality. However, studies analyzing outcomes before and after the implementation of NBS programs remain limited. This study sought to compare the outcomes of SCID patients identified through Switzerland's national SCID NBS program, introduced in January 2019, with those of a historical cohort diagnosed between 2007 and 2019. The study included seven patients (32%) identified through NBS, and 15 (68%) born before NBS implementation and diagnosed based on clinical signs. Children in the NBS group were younger at diagnosis (median age 9 days vs 9 months, P = .002) and at hematopoietic stem cell transplantation (HSCT, median age 5 months vs 11 months, P = .003) compared to the clinical group. The NBS group had a lower incidence of infections before HSCT (29% vs 93%, P = .004). Although not statistically significant, the overall survival rate on last follow-up was higher in the NBS group (86% vs 67%, P = .62). Importantly, patients with active infections undergoing HSCT had a significantly lower overall survival probability compared to those without (P = .01). In conclusion, the introduction of NBS in Switzerland has led to earlier and often asymptomatic diagnosis of affected children, enabling timely intervention, infection prevention, and prompt treatment. These factors have contributed to higher survival rates in the NBS group. These findings underscore the critical importance of NBS for SCID, offering potential life-saving benefits through early detection and intervention.

Sequence variants in the BTD underlying biotinidase deficiency in families of Pakistani origin.

BACKGROUND: Biotinidase deficiency (BTD) is a rare autosomal recessive metabolic disease, which develops neurological symptoms because of the impaired biotin recycling. Pathogenic mutations on BTD gene cause BTD deficiency. The clinical features and mutation analysis of Pakistani children with BTD deficiency have rarely been described. Herein, for the first time, we report the clinical features, BTD gene mutations and biochemical analysis of seven symptomatic children with BTD deficiency from Pakistan. METHODS: Seven suspected BTD-deficient patients who presented abnormal organic acid profiles and clinical features were subjected to Sanger sequencing to identify pathogenic mutations in the BTD gene. The results were analyzed by Mutation Surveyor Software. RESULTS: All seven patients exhibited common biotinidase deficiency symptoms including hypotonia, developmental delay and seizures. Biochemical analysis shows marked excretion of 3-hydroxy isovalerate in all cases, followed by 3-hydroxy propionate and methyl citrate. Sanger sequencing revealed one frame-shift mutation, c.98_104delinsTCC (p.Cys33Phefs), and two missense mutations, c.1612C>A (p.Arg538Ser) and c.1330G>C (p.Asp444His). All mutations were in the homozygous state and classified as pathogenic in published studies and mutation databases. CONCLUSIONS: This study has validated the BTD variants as the underlying cause of biotinidase deficiency in which molecular testing of BTD is supported by urinary organic acid analysis and clinical diagnosis. Secondly, the strength of the local availability of this test in Pakistan will paved the way for the neonatal screening of biotinidase deficiency.

Distribution of pathogenic variants in the CFTR gene in a representative cohort of people with cystic fibrosis in the Kingdom of Bahrain.

BACKGROUND: Cystic fibrosis (CF) is a rare multi-systemic recessive disorder. The spectrum and the frequencies of CFTR mutations causing CF vary amongst different populations in Europe and the Middle East. In this study, we characterised the distribution of CF-causing mutations (i.e. pathogenic variants in the  CFTR gene) in a representative CF cohort from the Kingdom of Bahrain based on a three-decade-long analysis at a single tertiary centre. We aim to improve CF genetic diagnostics, introduce of CF neonatal screening and provide CFTR modulator therapy (CFTRm). METHODS: CFTR genotyping  and associated clinical information were drawn from a longitudinal cohort. We sequenced 56 people with CF (pwCF) that had one or both CFTR mutations unidentified and carried out comprehensive bioinformatic- and family-based segregation analyses of detected variants, including genotype-phenotype correlations and disease incidence estimates. The study methodology could serve as a basis for other non-European CF populations with a high degree of consanguinity. RESULTS: Altogether 18 CF-causing mutations  were identified, 15 of which were not previously detected in Bahrain, accounting for close to 100% of all population-specific alleles. The most common alleles comprise c.1911delG [2043delG; 22.8%], c.2988+1G > A [3120+1G>A; 16.3%], c.2989-1G>A [3121-1G>A; 14.1%], c.3909C>G [N1303K; 13.0%], and c.1521_1523delCTT [p.PheF508del; 7.6%]. Although the proportion of 1st cousin marriages has decreased to 50%, the frequency of homozygosity in our pwCF is 67.4%, thereby indicating that CF still occurs in large, often related, families. pwCF in Bahrain present with faltering growth, pancreatic insufficiency and classical sino-pulmonary manifestations. Interestingly, two pwCF also suffer from sickle cell disease. The estimated incidence of CF in Bahrain based on data from the last three decades is 1 in 9,880 live births. CONCLUSION: The most commonCF-causing  mutations in Bahraini pwCF were identified, enabling more precise diagnosis, introduction of two-tier neonatal screening and fostering administration of CFTRm.

From diagnosis to management: current perspectives on congenital cytomegalovirus infection.

PURPOSE OF REVIEW: Congenital CMV (cCMV) infection is the most common infection of newborns and a leading cause of hearing loss and other neurologic disabilities in children. This review focuses on the diagnosis, presentation and management of cCMV infection. RECENT FINDINGS: Cytomegalovirus is one of the leading causes of sensorineural hearing loss in children. It also leads to neurodevelopmental disabilities and learning problems throughout childhood in both symptomatic and asymptomatic newborns. Urine and saliva PCR testing are the preferred methods of testing newborn infants for cCMV. In recent years, newborn-targeted and universal screening programs have been implemented in several states and major medical centers with the goal of identifying infected infants at risk for hearing loss. Treatment for infants diagnosed with cCMV infection should be limited to those who are moderately to severely symptomatic at birth with cCMV infection, though treatment may be beneficial for children who are asymptomatic with isolated sensorineural hearing loss. SUMMARY: As more children with cCMV are being identified through newborn screening, understanding the clinical presentation and sequelae is important for appropriate management of children with cCMV.