Province-wide Biliary Atresia Home Screening Program in British Columbia: Evaluation of First 2 Years.

BACKGROUND AND OBJECTIVES: Biliary atresia (BA), a rare newborn liver disease, is the leading cause of liver-related death in children. Early disease recognition and timely surgical Kasai hepatoportoenterostomy (KP) offers long-term survival without liver transplant. Universal BA screening in Taiwan using infant stool color cards (ISCCs) has proven effectiveness. We report our experience with infant stool color card (ISCC) BA screening in a province-wide program in British Columbia (BC). The objective of this study is to assess program performance and cost from launch April 1, 2014 to March 31, 2016. METHODS: ISCCs distributed to families upon maternity ward discharge. Parents were instructed to monitor their infant's stool color for 1 month and contacted the screening center with concerns. The number of live births, ISCC distribution, BA cases, and costs were recorded. Cases with Program screen success had both acholic stool recognition (ISCC screen success) and timely referral for BA. RESULTS: All 126 maternity units received ISCCs. Of 87,583 live births there were 6 BA cases. Of the 5 cases with ISCC Screen Success 3 had Program Screen Success. The median KP age in the program screen success and failure groups was 49 (42-52) and 116 (49-184) days, respectively. Program sensitivity was 50%, specificity 99%, positive predictive value 4%, and negative predictive value 99%. A random sample of 1054 charts at BC Children's Hospital found an ISCC distribution rate of 94%. After a phase-in period, the annual program cost was $30,033.82, and the ISCC cost per birth was $0.68. CONCLUSIONS: The screening program has high specificity and distribution with low cost. Successful program case identification had earlier age at KP. Program modifications aim to improve sensitivity. Longer-term studies will determine program impact on health outcomes.

Prediction of obstetrical risk using maternal serum markers and clinical risk factors.

OBJECTIVE: Abnormal maternal serum analytes (pregnancy associated plasma protein A, total human chorionic gonadotropin, alpha fetoprotein, Inhibin A, and unconjugated estriol) measured as part of aneuploidy screening programs have been associated with adverse obstetrical outcomes in euploid pregnancies. This study aimed to determine if their predictive ability could be enhanced with additional information on obstetrical history. METHOD: Forty-five thousand two hundred eighty-seven women participated in the screening program and delivered euploid singleton infants between 2010 and 2012 in British Columbia, Canada. A split-sample design was used to develop and validate prognostic models for serious perinatal events (stillbirth, preterm birth <32 weeks, or HELLP syndrome) and severe pre-eclampsia [pre-eclampsia with preterm birth <34 weeks or small for gestational age <10th percentile] using logistic regression. RESULTS: Three thousand five hundred four women (7.7%) had at least one abnormal marker using standard cut-off values. The combination of serum markers and clinical risk factors improved the ability of statistical models to predict a serious perinatal event [area under the curve (AUC) = 0.62] and severe pre-eclampsia (AUC = 0.78) compared with serum markers or clinical risk factors alone. CONCLUSIONS: While detection rates are low, the combination of maternal serum markers and obstetrical history helps to identify a small subset of women at higher risk for serious perinatal events and severe pre-eclampsia.

Mutations in HFE2 cause iron overload in chromosome 1q-linked juvenile hemochromatosis.

Juvenile hemochromatosis is an early-onset autosomal recessive disorder of iron overload resulting in cardiomyopathy, diabetes and hypogonadism that presents in the teens and early 20s (refs. 1,2). Juvenile hemochromatosis has previously been linked to the centromeric region of chromosome 1q (refs. 3-6), a region that is incomplete in the human genome assembly. Here we report the positional cloning of the locus associated with juvenile hemochromatosis and the identification of a new gene crucial to iron metabolism. We finely mapped the recombinant interval in families of Greek descent and identified multiple deleterious mutations in a transcription unit of previously unknown function (LOC148738), now called HFE2, whose protein product we call hemojuvelin. Analysis of Greek, Canadian and French families indicated that one mutation, the amino acid substitution G320V, was observed in all three populations and accounted for two-thirds of the mutations found. HFE2 transcript expression was restricted to liver, heart and skeletal muscle, similar to that of hepcidin, a key protein implicated in iron metabolism. Urinary hepcidin levels were depressed in individuals with juvenile hemochromatosis, suggesting that hemojuvelin is probably not the hepcidin receptor. Rather, HFE2 seems to modulate hepcidin expression.

Hepcidin in iron overload disorders.

Hepcidin is the principal regulator of iron absorption in humans. The peptide inhibits cellular iron efflux by binding to the iron export channel ferroportin and inducing its internalization and degradation. Either hepcidin deficiency or alterations in its target, ferroportin, would be expected to result in dysregulated iron absorption, tissue maldistribution of iron, and iron overload. Indeed, hepcidin deficiency has been reported in hereditary hemochromatosis and attributed to mutations in HFE, transferrin receptor 2, hemojuvelin, and the hepcidin gene itself. We measured urinary hepcidin in patients with other genetic causes of iron overload. Hepcidin was found to be suppressed in patients with thalassemia syndromes and congenital dyserythropoietic anemia type 1 and was undetectable in patients with juvenile hemochromatosis with HAMP mutations. Of interest, urine hepcidin levels were significantly elevated in 2 patients with hemochromatosis type 4. These findings extend the spectrum of iron disorders with hepcidin deficiency and underscore the critical importance of the hepcidin-ferroportin interaction in iron homeostasis.

Identification of a novel gene (HSN2) causing hereditary sensory and autonomic neuropathy type II through the Study of Canadian Genetic Isolates.

Hereditary sensory and autonomic neuropathy (HSAN) type II is an autosomal recessive disorder characterized by impairment of pain, temperature, and touch sensation owing to reduction or absence of peripheral sensory neurons. We identified two large pedigrees segregating the disorder in an isolated population living in Newfoundland and performed a 5-cM genome scan. Linkage analysis identified a locus mapping to 12p13.33 with a maximum LOD score of 8.4. Haplotype sharing defined a candidate interval of 1.06 Mb containing all or part of seven annotated genes, sequencing of which failed to detect causative mutations. Comparative genomics revealed a conserved ORF corresponding to a novel gene in which we found three different truncating mutations among five families including patients from rural Quebec and Nova Scotia. This gene, termed "HSN2," consists of a single exon located within intron 8 of the PRKWNK1 gene and is transcribed from the same strand. The HSN2 protein may play a role in the development and/or maintenance of peripheral sensory neurons or their supporting Schwann cells.