Prospective cohort study of genomic newborn screening: BabyScreen+ pilot study protocol

INTRODUCTION

Newborn bloodspot screening (NBS) is a highly successful public health programme that uses biochemical and other assays to screen for severe but treatable childhood-onset conditions. Introducing genomic sequencing into NBS programmes increases the range of detectable conditions but raises practical and ethical issues. Evidence from prospectively ascertained cohorts is required to guide policy and future implementation. This study aims to develop, implement and evaluate a genomic NBS (gNBS) pilot programme.

METHODS AND ANALYSIS

The BabyScreen+ study will pilot gNBS in three phases. In the preimplementation phase, study materials, including education resources, decision support and data collection tools, will be designed. Focus groups and key informant interviews will also be undertaken to inform delivery of the study and future gNBS programmes. During the implementation phase, we will prospectively recruit birth parents in Victoria, Australia, to screen 1000 newborns for over 600 severe, treatable, childhood-onset conditions. Clinically accredited whole genome sequencing will be performed following standard NBS using the same sample. High chance results will be returned by genetic healthcare professionals, with follow-on genetic and other confirmatory testing and referral to specialist services as required. The postimplementation phase will evaluate the feasibility of gNBS as the primary aim, and assess ethical, implementation, psychosocial and health economic factors to inform future service delivery.

ETHICS AND DISSEMINATION

This project received ethics approval from the Royal Children's Hospital Melbourne Research Ethics Committee: HREC/91500/RCHM-2023, HREC/90929/RCHM-2022 and HREC/91392/RCHM-2022. Findings will be disseminated to policy-makers, and through peer-reviewed journals and conferences.

Reproductive genetic carrier screening for cystic fibrosis, fragile X syndrome and spinal muscular atrophy: patterns of community and healthcare provider participation in a Victorian screening program

BACKGROUND

The Royal Australian and New Zealand College of Obstetricians and Gynaecologists and The Royal Australian College of General Practice recommend that information on carrier screening for at least the most common inherited genetic conditions in our population, that is, thalassaemia, cystic fibrosis (CF), spinal muscular atrophy (SMA), and fragile X syndrome (FXS), should be offered to all women planning pregnancy or in early pregnancy regardless of family history or ethnicity. The aim of this study was to investigate patterns of participation by healthcare providers (HCP) and the community in screening.

METHODS

Participation in a Victorian program screening for CF, SMA and FXS between September 2013 and October 2018 was analysed. Requesting HCP and patient data were extracted from screening request forms. Data were analysed with respect to profession of requesting HCP, and characteristics of women screened (age, pregnancy status, socioeconomic status, geographic location, and family history of CF, SMA or FXS). In total, 21 172 women and 1288 HCPs participated in the program over this period.

RESULTS

There was a steep socioeconomic gradient in screening uptake, with nearly half the women screened (10 349) being in the highest socioeconomic quintile. The screening rate was much higher in metropolitan areas than in regional areas. Obstetricians made most of the requests for screening, whereas 20% of requests were by GPs. Most participating GPs only made a single screening request (78%) and very few GPs made >100 screening requests compared with obstetricians (0.2% vs 17%). GPs were more likely to screen women before pregnancy compared with obstetricians (47% vs 11%). Approximately 1.5% of Victorian women of child-bearing age and 3% of pregnant Victorian women were screened by this program over the period of this study.

CONCLUSION

This study highlights the translation gap between recommendations and practice, with marked inequity of access to reproductive genetic carrier screening in relation to socioeconomic status and geography. Increased participation by GPs could improve community access to reproductive genetic carrier screening, particularly access to preconception screening. Addressing the causes of inequity of access will allow more women and couples the opportunity to make informed choices about participation in screening.

Health practitioners' perceptions of the barriers and enablers to the implementation of reproductive genetic carrier screening: A systematic review

Background

As interest in reproductive genetic carrier screening rises, with increased availability, the role of healthcare practitioners is central in guiding uptake aligned with a couples' values and beliefs. Therefore, practitioners' views on implementation are critical to the success of any reproductive genetic carrier screening programme.

Aim

To explore healthcare practitioners' perceptions of the barriers and enablers to implementation.

Materials & Methods

We undertook a systematic review of the literature searching seven databases using health practitioner, screening and implementation terms returning 490 articles.

Results

Screening led to the inclusion of 26 articles for full‐text review. We found three interconnected themes relating to reproductive genetic carrier screening: (i) use and impact, (ii) practitioners' beliefs and expectations and (iii) resources.

Discussion

Barriers and enablers to implementation were present within each theme and grouping these determinants by (a) community for example lack of public interest, (b) practitioner for example lack of practitioner time and (c) organisation for example lack of effective metrics, reveals a preponderance of practitioner barriers and organisational enablers. Linking barriers with potential enablers leaves several barriers unresolved (e.g., costs for couples) implying additional interventions may be required.

Conclusion

Future research should draw on the findings from this study to develop and test strategies to facilitate appropriate offering of reproductive genetic carrier screening by healthcare practitioners.

What is already known?

Availability of reproductive genetic carrier screening is rising.

Screening is often focused on ethnically specific conditions or for those with a family history of disease.

Commonly, carriers do not have family history of disease.

What does this review add?

Identifies practitioner barriers to implementation of reproductive genetic carrier screening, for example, beliefs and expectations.

Matches identified practitioner barriers to enablers to implementation.

Highlights where additional implementation support is required, for example, lack of practitioner confidence.

Gene selection for the Australian Reproductive Genetic Carrier Screening Project ("Mackenzie's Mission")

Reproductive genetic carrier screening aims to offer couples information about their chance of having children with certain autosomal recessive and X-linked genetic conditions. We developed a gene list for use in "Mackenzie's Mission", a research project in which 10,000 couples will undergo screening. Criteria for selecting genes were: the condition should be life-limiting or disabling, with childhood onset, such that couples would be likely to take steps to avoid having an affected child; and/or be one for which early diagnosis and intervention would substantially change outcome. Strong evidence for gene-phenotype relationship was required. Candidate genes were identified from OMIM and via review of 23 commercial and published gene lists. Genes were reviewed by 16 clinical geneticists using a standard operating procedure, in a process overseen by a multidisciplinary committee which included clinical geneticists, genetic counselors, an ethicist, a parent of a child with a genetic condition and scientists from diagnostic and research backgrounds. 1300 genes met criteria. Genes associated with non-syndromic deafness and non-syndromic differences of sex development were not included. Our experience has highlighted that gene selection for a carrier screening panel needs to be a dynamic process with ongoing review and refinement.

Alcohol use and depression during adolescence and young adulthood: a summary and interpretation of mixed findings

Alcohol Use Disorder (AUD) and alcohol misuse are common among adolescents and young adults and are associated with significant personal and societal problems. Similarly, Major Depressive Disorder (MDD) and depressive symptoms are prevalent in this population and when they co-occur with alcohol misuse lead to even more severe consequences. Numerous studies have investigated the association between depressive symptoms, AUD and various drinking behaviors presenting an unclear picture. In this review we summarize studies among adolescents and young adults that have examined these relationships. From this review it emerges that several factors affect results, including study design (cross-sectional vs longitudinal), participants' age (adolescents vs young adults), severity of problems considered (AUD vs heavy drinking; MDD vs depressive symptoms), and gender. Adolescents with AUD are at higher risk for MDD in particular at a younger age. During adolescence, several drinking behaviors, including weekly alcohol use and heavy drinking, increase the risk for depressive symptoms and MDD, while during young adulthood primarily AUD, but not other drinking behaviors, is associated with increased risk for MDD. Gender may have an effect on the association between depression and drinking behaviors but its role is still unclear. Some evidence suggests that the association between AUD and MDD is bidirectional such that mood problems contribute to the onset of alcohol problems and vice-versa. More longitudinal studies are needed to examine these associations in young adults and to clarify the effect of gender on these associations. To date, findings suggest the critical need to reduce any alcohol use at a young age and to treat both depressive symptoms and AUD to prevent the occurrence of comorbid disorders.

Genomic diversity and differentiation of a managed island wild boar population

The evolution of island populations in natural systems is driven by local adaptation and genetic drift. However, evolutionary pathways may be altered by humans in several ways. The wild boar (WB) (Sus scrofa) is an iconic game species occurring in several islands, where it has been strongly managed since prehistoric times. We examined genomic diversity at 49 803 single-nucleotide polymorphisms in 99 Sardinian WBs and compared them with 196 wild specimens from mainland Europe and 105 domestic pigs (DP; 11 breeds). High levels of genetic variation were observed in Sardinia (80.9% of the total number of polymorphisms), which can be only in part associated to recent genetic introgression. Both Principal Component Analysis and Bayesian clustering approach revealed that the Sardinian WB population is highly differentiated from the other European populations (F_ST=0.126–0.138), and from DP (F_ST=0.169). Such evidences were mostly unaffected by an uneven sample size, although clustering results in reference populations changed when the number of individuals was standardized. Runs of homozygosity (ROHs) pattern and distribution in Sardinian WB are consistent with a past expansion following a bottleneck (small ROHs) and recent population substructuring (highly homozygous individuals). The observed effect of a non-random selection of Sardinian individuals on diversity, F_ST and ROH estimates, stressed the importance of sampling design in the study of structured or introgressed populations. Our results support the heterogeneity and distinctiveness of the Sardinian population and prompt further investigations on its origins and conservation status.

Oncogenic suppression of apoptosis uncovers a Rac1/JNK proliferation pathway activated by loss of Par3

Disruption of epithelial organization and loss of growth control are universal features of carcinomas, yet how these features are linked during cancer progression remains poorly understood. Cell polarity proteins control cellular and tissue organization and are emerging as important mediators of cancer progression. The Par3 polarity protein is a molecular scaffold that functions to recruit and spatially organize signaling factors, and was recently identified as a suppressor of breast cancer invasion and metastasis. Here, we show that loss of Par3 in mammary epithelial cells promotes apoptosis, and that oncogenic Notch overcomes the apoptotic signal to reveal an unexpected pro-proliferative role for loss of Par3 in mammary tumors. In this context, loss of Par3 deregulates Rac1 activity to activate Jun N-terminal Kinase-dependent proliferation and tumor growth. Thus, we demonstrate a mechanism by which loss of Par3 promotes proliferation and tumorigenesis, which supports a tumor-suppressive function for Par3 in the mammary epithelium.

Offering fragile X syndrome carrier screening: a prospective mixed-methods observational study comparing carrier screening of pregnant and non-pregnant women in the general population

INTRODUCTION

Fragile X syndrome (FXS) is the leading cause of inherited intellectual and developmental disability. Policy development relating to carrier screening programmes for FXS requires input from large studies examining not only test uptake but also psychosocial aspects. This study will compare carrier screening in pregnant and non-pregnant populations, examining informed decision-making, psychosocial issues and health economics.

METHODS AND ANALYSIS

Pregnant and non-pregnant women are being recruited from general practices and obstetric services. Women receive study information either in person or through clinic mail outs. Women are provided pretest counselling by a genetic counsellor and make a decision about testing in their own time. Data are being collected from two questionnaires: one completed at the time of making the decision about testing and the second 1 month later. Additional data are gathered through qualitative interviews conducted at several time points with a subset of participating women, including all women with a positive test result, and with staff from recruiting clinics. A minimum sample size of 500 women/group has been calculated to give us 88% power to detect a 10% difference in test uptake and 87% power to detect a 10% difference in informed choice between the pregnant and non-pregnant groups. Questionnaire data will be analysed using descriptive statistics and multivariate logistic regression models. Interview data will be thematically analysed. Willingness-to-pay and cost effectiveness analyses will also be performed. Recruitment started in July 2009 and data collection will be completed by December 2013.

ETHICS AND DISSEMINATION

Ethics approval has been granted by the Universities of Melbourne and Western Australia and by recruiting clinics, where required. Results will be reported in peer-reviewed publications, conference presentations and through a website http://www.fragilexscreening.net.au. The results of this study will make a significant contribution to discussions about the wider introduction of population carrier screening for FXS.

Comparative study of the osteoblastic activity of two implant systems (Endopore versus Entegra) utilizing single photon emission computed tomography (SPECT): experimental study in pigs model

Implantology has been an important component of dental management for over forty years, and during that period, many configurations of implant materials and methods have been developed. As empirical and clinical research yield new implant materials, there has been need to test and compare these materials to provide the most cost-effective and efficient implants. Evaluation of efficiency of implants has relied heavily on histological and radiological methods, but these one-dimensional measurement methods fail to evaluate the osteoblastic activity and osseointegration properties of putative implants. In this report, we describe the use of a quantitative single photon emission computed tomography (SPECT) as a tool for comparing the osseointegrating capabilities of two types of implants.

Comparative study of osteoblastic activity of same implants (Endopore) in the immediate extraction site utilizing single photon emission computerized tomography: peri-implant autogeneous bone grafting with GTR versus no peri-implant bone grafting--experimental study in pig model

The study was designed to exploit the single photon emission computerized tomography (SPECT) to compare osteoblastic activity of two implant systems: an Endopore implant (Beaded implants) placed immediately into an extraction socket in conjunction with peri-implant autogenous grafting supplemented with a guided tissue regeneration (GTR) technique, and an Endopore implant placed immediately into the extraction socket without peri-implant grafting and GTR. Endopore implants of the same size (12 mm x 4.1 mm INT-Hex) were placed in fresh extraction sockets in the canine-tooth region of the pigs jaw. The implant on the right side had peri-implant bone grafting utilizing autogenous bone together with cytoplast resorbable GTR membrane, whilst the implant on the left side received no peri-implant bone grafting. Osteoblastic activity was evaluated 81 days (11 weeks and 4 days) post implantation using the SPECT imaging technique. The SPECT imaging revealed more osteoblastic activity on the side with peri-implant bone grafting as compared with the site without peri-implant bone grafting. The result suggests that peri-implant bone grafting with GTR around the immediate implant showed more osteoblastic activity and thus enhanced osseointegration when compared with the implant without bone grafting and GTR. Bone grafting and GTR should be encouraged as a standard procedure with dental implants.

Single photon emission computerized tomography in the evaluation of the osteoblastic activities of a new bone regeneration technique: analysis of 12 mandibular sites in six experimental pigs

OBJECTIVES

To utilize single photon emission computerized tomography performed in sequence to determine the osseo-integrating capabilities and osteoblastic activities of a new bone regeneration technique called the membrane--sandwich technique (Ogunsalu sandwich bone regenerating technique) and to compare the quality and quantity of bone formed by this bone regeneration unit to bone regeneration obtained by using the same particulate bone grafting material covered with interceed (another type of bio-resorbable membrane).

DESIGN AND METHOD

Single photon emission computerized tomography bone imaging was performed in sequence on the mandible of a total of 6 pigs on both the right and left side (total of 12 sites) at two and a half hours following the injection of technetium 99m methylene diphosphate. Imaging was performed using a Siemen Orbitar II gamma camera. The projection data was acquired in a 128 x 128 matrix over 180 arc and SPECT reconstruction was performed using a filtered back projector method with a Shepp-Logan Hanning filter and a cut-off frequency of 0.4. The surgical defect on one side of the jaw was treated with the sandwich unit with Bio-oss particulate bone within it, while the other side contained the same quantity of Bio-oss as in the left side but just covered with interceed membrane. The osteoblastic uptake on the side with the classical sandwich was compared to the side with the particulate bone covered with interceed membrane for dynamic physiological activities. The average activity for both sides was calculated and compared.

RESULT

For all the 12 sites, osteoblastic activities were recorded and indicated that vascularized bone was formed at all the experimental sites. Autogenous bone graft was confirmed to be superior to xenograft using this sandwich technique. Furthermore, the osteoblastic activities on the sandwich side were seen to be more when compared with the control side (Interceed side).

CONCLUSION

The Ogunsalu sandwich bone regeneration technique has been successfully evaluated with SPECT which shows osteoblastic activity with formation of vascularized bone which integrates with the surrounding bone.

Single photon emission computerized tomography and histological evaluation in the validation of a new technique for closure of oro-antral communication: an experimental study in pigs

Various bone regeneration techniques have evolved recently but controversies regarding vascularization and integration of such bone grafting techniques have led occasionally to animal experiment to validate such techniques. The objective of this study was to evaluate the evidence of vascularization and osseo-integration of a new bone regeneration technique utilized for the closure of oro-antral communication (OAC) by an experimental model in which Single Photon Emission computerized Tomography and histological studies were conducted in pigs. We conclude that the sandwich technique used for the closure of OAC results in a vascularized new bone formation which eventually osseo-integrate with the surrounding bone. Also, this experimental study confirmed that autogeneous bone graft was superior to xenografts when used within the sandwich unit.

Animal genomics for animal health report: critical needs, problems to be solved, potential solutions, and a roadmap for moving forward

The first International Symposium on Animal Genomics for Animal Health, held at the World Organisation for Animal Health (OIE) Headquarter, 23-25 October, 2007, Paris, France, assembled more than 250 participants representing research organizations from 26 countries. The symposium included a roundtable discussion on critical needs, challenges and opportunities, and a forward look at the potential applications of animal genomics in animal health research. The aim of the roundtable discussion was to foster a dialogue between scientists working at the cutting edge of animal genomics research and animal health scientists. In an effort to broaden the perspective of the roundtable discussion, the organizers set out four priority areas to advance the use of genome-enabled technologies in animal health research. Contributions were obtained through open discussions and a questionnaire distributed at the start of the symposium. This symposium report provides detailed summaries ofthe outcome ofthe roundtable discussion for each of the four priority areas. For each priority, the problems needing to be solved, according to the views of the participants, are identified, including potential solutions, recommendations, and lastly, concrete steps that could be taken to address these problems. This report serves as a roadmap to steer research priorities in animal genomics research.

Is self-reported improvement in osteoarthritis pain and disability reflected in objective measures?

OBJECTIVE

To determine if self-reported improvements in pain and function correlate with improvement in objective measures of disease in osteoarthritis (OA).

METHODS

Individuals with disabling hip/knee OA were assessed 7 years apart by questionnaire [sociodemographics, body mass index, and Western Ontario and McMaster University Osteoarthritis Index (WOMAC) scores] and physical [range of motion (ROM), disease activity based on joint stress pain, erythema, warmth, effusion] and radiographic examination of the hips and knees (Kellgren-Lawrence grade). Changes over time were expressed as improved, unchanged, or worse based on a priori criteria.

RESULTS

Of 69 eligible patients, 43 (64%) with a mean age of 76.3 years participated; 77% were female. For WOMAC scores, 25% and 19% reported improved pain and function, respectively. For joint ROM, disease activity, and radiographic grade, 0% to 30% of participants were improved. However, improvements in WOMAC scores were not associated with improvements in any of the other measures (r < 0.24 for all).

CONCLUSION

One-quarter of participants reported significant improvements in WOMAC pain and disability after 7 years' followup. However, these improvements were not associated with similar improvements in joint ROM, disease activity, or radiographic grade. Greater understanding of the determinants of self-reported improvements in arthritis status, in particular the role of adaptation, is warranted.

Genetic diversity in European pigs utilizing amplified fragment length polymorphism markers

The use of DNA markers to evaluate genetic diversity is an important component of the management of animal genetic resources. The Food and Agriculture Organisation of the United Nations (FAO) has published a list of recommended microsatellite markers for such studies; however, other markers are potential alternatives. This paper describes results obtained with a set of amplified fragment length polymorphism (AFLP) markers as part of a genetic diversity study of European pig breeds that also utilized microsatellite markers. Data from 148 AFLP markers genotyped across samples from 58 European and one Chinese breed were analysed. The results were compared with previous analyses of data from 50 microsatellite markers genotyped on the same animals. The AFLP markers had an average within-breed heterozygosity of 0.124 but there was wide variation, with individual markers being monomorphic in 3-98% of the populations. The biallelic and dominant nature of AFLP markers creates a challenge for their use in genetic diversity studies as each individual marker contains limited information and AFLPs only provide indirect estimates of the allelic frequencies that are needed to estimate genetic distances. Nonetheless, AFLP marker-based characterization of genetic distances was consistent with expectations based on breed and regional distributions and produced a similar pattern to that obtained with microsatellites. Thus, data from AFLP markers can be combined with microsatellite data for measuring genetic diversity.

Lymphoscintigraphic evaluation of chronic lower limb oedema

Ultrasound, computed tomography (CT), magnetic resonance imaging (MRI), venography, lymphoscinti-graphy (LS) and contrast lymphography are frequently utilized in the evaluation of lower limb oedema but no clinical data from the Caribbean have been published on the role of LS despite its well-recognized clinical application. The successful clinical application of CT, colour doppler sonography and MRI in differentiating the various causes of lower limb oedema is well understood. Lymphoscintigraphy has found less acceptability especially in the Caribbean where nuclear imaging techniques are only now currently being developed. This paper describes the initial experience with this technique in 15 patients over a five-year period and discusses its value when lower limb lymphoedema is suspected. Scintigrams were analyzed for visualization of lymph vessels and lymph nodes, dilatation of lymphatic vessels, collaterals and dermal back flow. Lymphoscintigrams were classified as normal (n = 5) or consistent with lymphoedema (n = 10). Failure to visualize lymphatic vessels occurred in two cases of suspected primary lymphoedema. In the remaining eight cases of secondary lymphoedema, a positive study based on altered lymphatic flow and anatomy was recorded. An alternative explanation was offered in three out of five cases in which a normal lymphoscintigram was obtained.

The role of labelled red blood cell scintigraphy in the detection of acute gastrointestinal bleeding

This paper describes the experience with 99m Technetium labelled red blood cell (99mTc RBC) scintigraphy in twenty-two patients presenting with acute gastrointestinal (GI) tract bleeding. Studies were positive in thirteen cases--eight from the lower GI tract and five from the upper. The data from surgical intervention were available in ten cases. Scintigraphy cannot diagnose the cause of GI bleeding, as it is a nonspecific study. Its usefulness lies in its ability to accurately diagnose the bleeding site, as was shown in this study where there was good surgical correlation. The simplicity, reproducibility and reliability of the technique, particularly when bleeding rates are low and intermittent, make it, in our view, the first line of investigation in any patient with suspected bleeding from the colon or upper GI tract if endoscopic evaluation is not possible in the latter. Its current under-utilisation in the Caribbean may be a reflection of the lack of nuclear imaging facilities.

The role of quantitative single photon emission computerized tomography (SPECT) in the osseous integration process of dental implants

OBJECTIVE

To evaluate the integration process of endosseous dental implants by using quantitative bone single photon emission computerized tomography (SPECT).

METHODS

Five consecutive patients receiving titanium implants (Astra Tech, Mölndal, Sweden) in the normal edentulous jaw were evaluated by bone SPECT before loading and at regular intervals up to 5 months after loading. Osteoblastic activity at the implant site was compared with activity within the skull (reference) to calculate an osteoblastic activity index (AI).

RESULTS

A time activity curve obtained by plotting AI against time over 5 months showed 3 distinct phases of osteoblastic activity: (1) a rise in osteoblastic activity, part of which may reflect postoperative changes, (2) maximum activity about 1 month after implant, and (3) a gradual falloff in the AI, which returned to pre-implant levels at about 4 months.

CONCLUSIONS

We conclude that this method offers a simple, reproducible, objective, and physiologic approach to studying the osseous integration process that occurs after endosseous dental implants. In this small series of patients, this osseous integrative process appears to have become established approximately 4 months after loading. This method also has the capability of quantitating bone activity in absolute terms of microCi/gram (microcuries per gram) and can be useful when bone grafting and other surgical procedures are involved.

Porcine lung surfactant protein D: complementary DNA cloning, chromosomal localization, and tissue distribution

Porcine organs and lung surfactant have medically important applications in both xenotransplantation and therapy. We have started to characterize porcine lung surfactant by cloning the cDNA of porcine surfactant protein D (SP-D). SP-D and SP-A are important mediators in innate immune defense for the lung and possibly other mucosal surfaces. Porcine SP-D will also be an important reagent for use in existing porcine animal models for human lung infections. The complete cDNA sequence of porcine SP-D, including the 5' and 3' untranslated regions, was determined from two overlapping bacteriophage clones and by PCR cloning. Three unique features were revealed from the porcine sequence in comparison to SP-D from other previously characterized species, making porcine SP-D an intriguing species addition to the SP-D/collectin family. The collagen region contains an extra cysteine residue, which may have important structural consequences. The other two differences, a potential glycosylation site and an insertion of three amino acids, lie in the loop regions of the carbohydrate recognition domain, close to the carbohydrate binding region and thus may have functional implications. These variations were ruled out as polymorphisms or mutations by confirming the sequence at the genomic level in four different pig breeds. Porcine SP-D was shown to localize primarily to the lung and with less abundance to the duodenum, jejunum, and ileum. The genes for SP-D and SP-A were also shown to colocalize to a region of porcine chromosome 14 that is syntenic with the human and murine collectin loci.

Biotinidase deficiency: a treatable genetic disorder in the Saudi population

Biotinidase deficiency is an autosomal recessive genetic disorder which is not uncommon in the Saudi population. Biotinidase is responsible for biotin recycling and biotin is an essential cofactor for activation of the carboxylase enzymes. Absence of biotinidase leads to infantile or early childhood encephalopathy, seizure disorder, dermatitis, alopecia, neural deafness and optic atrophy. The disease can be diagnosed by simple fluorometric enzyme assay. Treatment with biotin is both cheap and simple, resulting in rewarding clinical recovery and normalization of the biochemical, neuroradiological and neurophysiological parameters. If neglected, however, a patient may die of acute metabolic acidosis or may suffer from permanent neural deafness and optic atrophy, with mental and motor handicap. We describe the detection and treatment of 20 cases of biotinidase deficiency in our hospital and recommend the introduction of a neonatal screening programme for this disorder

Contrast material and gallbladder kinetics: implications for same day sonography after intravenous pyelography or CT scanning

Sonographic examination of the gallbladder has allowed us to study the effects of various substances on this organ. A prospective study involving 77 patients was undertaken to evaluate the effects of intravenous or oral contrast agents on gallbladder volume changes in patients without known gallbladder disease. A mean volume after contraction of 24.8% was observed after administration of intravenous contrast agent (P < 0.01) and of 31.9% after oral administration (P < 0.01). This phenomenon of contraction of the gallbladder should therefore be recognized when sonographic or computed tomographic evaluation of the gallbladder is undertaken after imaging procedures that use radiographic contrast agents either intravenously or orally.

Biotinidase deficiency: a treatable genetic disorder in the Saudi population

Biotinidase deficiency is an autosomal recessive genetic disorder which is not uncommon in the Saudi population. Biotinidase is responsible for biotin recycling and biotin is an essential cofactor for activation of the carboxylase enzymes. Absence of biotinidase leads to infantile or early childhood encephalopathy, seizure disorder, dermatitis, alopecia, neural deafness and optic atrophy. The disease can be diagnosed by simple fluorometric enzyme assay. Treatment with biotin is both cheap and simple, resulting in rewarding clinical recovery and normalization of the biochemical, neuroradiological and neurophysiological parameters. If neglected, however, a patient may die of acute metabolic acidosis or may suffer from permanent neural deafness and optic atrophy, with mental and motor handicap. We describe the detection and treatment of 20 cases of biotinidase deficiency in our hospital and recommend the introduction of a neonatal screening programme for this disorder.

Wolman's disease: The King Faisal Specialist Hospital and Research Centre experience

BACKGROUND

Wolman's disease is a rare autosomal recessive lysosomal storage disease. A recent review indicates that approximately 50 patients have been reported in the world. Reports of patients from the Arabian peninsula are rare due to lack of awareness among pediatricians.

PATIENTS AND METHODS

We retrospectively reviewed the clinical, radiological, biochemical and histopathological findings of four Saudi patients diagnosed with Wolman's disease at King Faisal Specialist Hospital and Research Centre. The diagnosis was confirmed by deficient acid lipase activity in the leukocytes and fibroblasts, which was measured using 4-methylumbelliferyl palmitate.

RESULTS

All patients were failing to thrive with progressive hepatosplenomegaly. Abdominal x-ray revealed calcifications which were confirmed on abdominal CT scan. Peripheral blood film showed vacuolated lymphocytes and the bone marrow aspiration showed foamy histiocytes. Liver biopsy in one patient showed marked steatosis and elliptical empty clefs predominantly in the Kupffer cells, indicating cholesterol storage in the reticulo-endothelial cells. The acid lipase activity was less than 6% in all patients.

CONCLUSION

In all suspected cases of Wolman's disease, a plain abdominal x-ray should be obtained to check for the typical pattern of adrenal calcification characteristic of the disease, especially in any young infant with failure to thrive and progressive hepatosplenomegaly.

Myocardial perfusion scintigraphy using Tc99m labelled compounds: correlations with coronary angiography

The increasing incidence of ischaemic heart disease with high mortality rate and the recent introduction of Tc99m labelled myocardial perfusion imaging agents, along with the advent of a Coronary Angiography programme in Trinidad and Tobago, prompted the comparison of the sensitivity and specificity of myocardial perfusion scintigraphy (MPS) with coronary angiography (CA). Using a standard one-day code-differential imaging protocol Single Photon Emission Computed Tomography (SPECT), images of the left ventricular myocardium of 30 patients were obtained at rest and following exercise: These images were analyzed for perfusion defects to assess each of the three main coronary arteries; the left anterior descending artery (LAD), the right coronary artery (RCA) and the left circumflex artery (LCx). The data were then correlated with the angiographic findings. MPS yielded an overall sensitivity of 97.5% and a specificity of 83.6% when compared to CA. Discordant data were obtained in the analysis of nine vascular territories with scintigraphy producing eight false positives and one false negative. The false positive cases were seen in two males and four females. Of the males, one was discovered to have intramyocardial tunnelling of the LAD artery and the other demonstrated differential perfusion between the LAD and LCx arteries. Of the females, one was classified as having Syndrome X and another demonstrated differential perfusion between the LAD and LCx arteries; the other two cases were attributed to breast attenuation. The one false negative was obtained in a patient who demonstrated good collateral circulation on angiography. MPS thus compares very well with CA in assessing the three main myocardial vascular territories.

Characterization of 24 porcine (dA-dC)n-(dT-dG)n microsatellites: genotyping of unrelated animals from four breeds and linkage studies

Twenty-four PCR primer pairs were designed for the detection of porcine microsatellites. Polymorphism was investigated in 76 unrelated animals from four different breeds: Duroc, Landrace, Hampshire, and Yorkshire. Compared with human microsatellites, a general lower heterozygosity was detected; however, for each microsatellite a significant variation between breeds in number of alleles and heterozygosity was seen. Mean heterozygosity was found to be significantly higher (P < 0.01%) in the Yorkshire breed than in the other three breeds. Linkage analyses with the CEPH linkage packet were performed in a backcross family comprising 45 animals, of which 43 had informative meioses. Ten of the microsatellites could be assigned to six different linkage groups, demonstrating that linkage mapping with microsatellites can be carried out with great efficiency in a relatively small number of animals. Four of the linkage groups represent Chromosomes (Chrs) 4, 6, 7, and 8 respectively, while two linkage groups are unassigned.

First trimester prenatal diagnosis of Tay-Sachs disease using the sulfated synthetic substrate for hexosaminidase A

Uncultured and cultured embryonic trophoblastic tissue obtained by chorionic villus sampling (CVS) displays enzyme activity towards 4-methylumbelliferyl-2-acetamido-2-deoxy-beta-D-glucopyranosyl-6-sulfate (MUGS), a specific substrate for Hexosaminidase A (Hex A), the enzyme deficient in Tay-Sachs disease (TSD). Specific activity is comparable to that found in cultured amniocytes and fibroblasts. The enzyme activity has a pH optimum of 4.1 and an apparent Km of 6 x 10(-4) mol/L. Thirteen pregnancies in eight families at risk for TSD were monitored by CVS using MUGS as the Hex A substrate. Four fetuses were proven affected by enzyme analysis of fetal tissues and cultured fetal fibroblasts obtained at the time of termination of the pregnancies. Nine fetuses were judged to be unaffected. Eight babies were clinically normal while the other pregnancy is continuing. The use of MUGS as substrate for Hex A makes prenatal diagnosis by CVS of families at risk for TSD simple, direct and accurate.

Diagnosis of neural tube defects by estimation of amniotic fluid acetylcholinesterase

Acetylcholinesterase (AChE) activity in amniotic fluid was assayed directly by a reaction rate method at 30 degrees C using acetylthiocholine iodide as substrate and ethopropazine as a safe 'pseudo' cholinesterase inhibitor. Fresh samples from 101 normal pregnancies of 14-24 weeks gestation had a mean AChE activity of 2.56 u/l (SD 1.10). Elevated levels of AChE were found in association with open spina bifida (5.5-20.4 u/l), anencephaly (10.2-19.5 u/l), exomphalos (2.7-15.6 u/l), intrauterine death (30.2-59.3 u/l) and Turner's syndrome (36.4 u/l) but not with closed spina bifida or rhesus isoimmunisation. When AChE activity was expressed as a percentage of the total cholinesterase activity ('percentage AChE'), there was a good correlation between AChE activity and 'percentage AChE' in normal pregnancies and the values associated with the 37 pregnancies affected by open neural tube defects (NTD) fell outside the 99.9 per cent confidence limits of the normal group. Qualitative differences in cholinesterase activity could be demonstrated between the groups with exomphalos and open NTD. It is suggested that the assay might be used satisfactorily to demonstrate the presence of open NTD in affected pregnancies.