Roger B. Eaton

Neonatal Serologic Screening and Early Treatment for Congenital Toxoplasma gondii Infection

BACKGROUND Most infants with congenital Toxoplasma gondii infection have no symptoms at birth, but many will have retinal disease or neurologic abnormalities later in life. Early detection and treatment of congenital toxoplasmosis may reduce these sequelae. METHODS In Massachusetts since January 1986, and in New Hampshire since July 1988, newborns have been screened for intrauterine infection with T. gondii by means of an IgM capture immunoassay of blood specimens routinely collected for screening for metabolic disorders. Congenital infection is confirmed by assays for specific IgG and IgM antibodies in serum from infants and their mothers. For this study, infants with serologic evidence of infection underwent extensive clinical evaluation and received one year of treatment. RESULTS Through June 1992, 100 of 635,000 infants tested had positive screening tests. Congenital infection was confirmed in 52 infants, 50 of whom were identified only through neonatal screening and not through initial clinical examination. However, after the serologic results became available, more detailed examinations revealed abnormalities of either the central nervous system or the retina in 19 of 48 infants evaluated (40 percent). After treatment, only 1 of 46 children had a neurologic deficit (hemiplegia attributable to a cerebral lesion present at birth). Thirty-nine treated children had follow-up ophthalmologic examinations when one to six years old; four (10 percent) had eye lesions that may have developed postnatally (a macular lesion in one child and minor retinal scars in three). CONCLUSIONS Routine neonatal screening for toxoplasmosis identifies congenital infections that are subclinical, and early treatment may reduce the severe long-term sequelae.

Trends in Incidence Rates of Congenital Hypothyroidism Related to Select Demographic Factors: Data From the United States, California, Massachusetts, New York, and Texas

Primary congenital hypothyroidism (CH) is a common and preventable cause of intellectual disability. The incidence rate of CH has been reported to be increasing in the United States, but the factors behind the observed rate increase are not known. We summarize here the data presented at a workshop on CH, at which factors potentially related to the CH-incidence-rate increase (namely, race, ethnicity, sex, and birth outcomes) were evaluated. Data sources for the analyses included a national data set of newborn-screening results and state-specific data from newborn-screening programs in California, Massachusetts, New York, and Texas. The incidence rate of CH increased in the United States by 3% per year; however, an increase did not occur in all states, at a constant rate, or even at the same rate. Analysis of US data (1991–2000) showed a CH-incidence-rate increase only among white newborns. More recently, in California (2000–2007), the rate was constant in non-Hispanic newborns, but it increased among Hispanic newborns. In the national data, the CH-incidence rate increased similarly among boys and girls, whereas in Texas (1992–2006), the rate among boys increased significantly more than among girls and varied according to race and ethnicity. In Massachusetts (1995–2007), low birth weight newborns or newborns who had a delayed rise in thyrotropin concentration accounted for the majority of the recent rate increase. Race, ethnicity, sex, and pregnancy outcomes have affected the observed increasing incidence rate of CH, although there have been some inconsistencies and regional differences. The association with preterm birth or low birth weight could reflect the misclassification of some cases of transient hypothyroxinemia as true CH. Future studies of risk factors should focus on correct initial identification and reporting of demographic characteristics and pregnancy outcomes for cases of CH. In addition, long-term follow-up data of presumed cases of CH should be ascertained to differentiate true cases of CH from cases of transient hypothyroidism.

High-Throughput Multiplexed T-Cell–Receptor Excision Circle Quantitative PCR Assay with Internal Controls for Detection of Severe Combined Immunodeficiency in Population-Based Newborn Screening

BACKGROUND Real-time quantitative PCR (qPCR) targeting a specific marker of functional T cells, the T-cell-receptor excision circle (TREC), detects the absence of functional T cells and has a demonstrated clinical validity for detecting severe combined immunodeficiency (SCID) in infants. There is need for a qPCR TREC assay with an internal control to monitor DNA quality and the relative cellular content of the particular dried blood spot punch sampled in each reaction. The utility of the qPCR TREC assay would also be far improved if more tests could be performed on the same newborn screening sample. METHODS We approached the multiplexing of qPCR for TREC by attenuating the reaction for the reference gene, with focus on maintaining tight quality assurance for reproducible slopes and for prevention of sample-to-sample cross contamination. Statewide newborn screening for SCID using the multiplexed assay was implemented, and quality-assurance data were recorded. RESULTS The multiplex qPCR TREC assay showed nearly 100% amplification efficiency for each of the TREC and reference sequences, clinical validity for multiple forms of SCID, and an analytic limit of detection consistent with prevention of contamination. The eluate and residual ghost from a 3.2-mm dried blood spot could be used as source material for multiplexed immunoassays and multiplexed DNA tests (Multiplex Plus), with no disruption to the multiplex TREC qPCR. CONCLUSIONS Population-based SCID newborn screening programs should consider multiplexing for quality assurance purposes. Potential benefits of using Multiplex Plus include the ability to perform multianalyte profiling.

Guidelines for implementation of population-based newborn screening for severe combined immunodeficiency.

Severe combined immunodeficiency (SCID) is a Primary Immune Deficiency that is under consideration for population-based newborn screening (NBS) by many NBS programs, and has recently been recommended for inclusion in the US uniform panel of newborn screening conditions. A marker of SCID, the T cell receptor excision circle (TREC), is detectable in the newborn dried blood spot using a unique molecular assay as a primary screen. The New England Newborn Screening Program developed and validated a multiplex TREC assay in which both the TREC analyte and an internal control are acquired from a single punch and run in the same reaction. Massachusetts then implemented a statewide pilot SCID NBS program. The authors describe the rationale for a pilot SCID NBS program, a comprehensive strategy for successful implementation, the screening test algorithm, the screening follow-up algorithm and preliminary experience based on statewide screening in the first year. The Massachusetts experience demonstrates that SCID NBS is a program that can be implemented on a population basis with reasonable rates of false positives.

Identification of an infant with severe combined immunodeficiency by newborn screening.

Percent CD3 1% 49-84* CD3, absolute 10 cells/mcL 2,500-5,600 Percent CD3/CD4 0% 35-64 CD3/CD4, absolute 4 cells/mcL 1,600-4,000 Percent CD3/CD8 1% 12-28 CD3/CD8, absolute 8 cells/mcL 500-1,700 Percent CD3/CD16 or CD56 5% 4-18 CD3/CD16 or CD56, absolute 55 cells/mcL 160-1,100 Percent CD19 89% 6-32 CD19, absolute 1,010 cells/mcL 300-2,000 Concanavalin A 1,591 cpm 41,000 Phytohemagglutinin 2,313 cpm 82,000 Mitogen background 1,520 cpm

Epidemiology of congenital toxoplasmosis identified by population-based newborn screening in Massachusetts

Background. Fourteen years of newborn screening in Massachusetts for congenital toxoplasmosis infection identified subpopulations that appeared to have higher rates of infection. Elaborating an epidemiologic profile and risk correlates might aid implementing targeted prenatal education and newborn screening strategies with the goal of early postnatal treatment to prevent morbidity. Objective. To describe the epidemiology of congenital toxoplasmosis in Massachusetts and risk correlates of infection using birth certificate data. Methods. A case-control study was conducted based on Massachusetts birth certificate data. Cases were all infants with congenital toxoplasmosis identified by statewide universal newborn screening from 1988 to 1999. Controls were all children born on the same day as those infants in Massachusetts. Results. Factors that strongly predicted congenital toxoplasmosis infection were mother’s country of birth outside the US (especially the southeast Asian refugee origin countries of Cambodia and Laos), mother’s educational level and higher gravidity. Conclusions. More extensive, culturally and linguistically appropriate, prenatal education is needed for pregnant women, regardless of a mother’s educational level, especially for non-US-born mothers, and not focused only on primiparous women. Other states may be able to use their state-specific birth certificate data to compare risk profiles with those of Massachusetts to guide a toxoplasmosis screening policy on the basis of population similarities and differences.

Spectrum of medium-chain acyl-CoA dehydrogenase deficiency detected by newborn screening

OBJECTIVE. Our goal was to describe the clinical spectrum of medium-chain acyl-CoA dehydrogenase deficiency detected by routine newborn screening and assess factors associated with elevations of octanoylcarnitine in newborns and characteristics associated with adverse clinical consequences of medium-chain acyl-CoA dehydrogenase deficiency. METHODS. The first 47 medium-chain acyl-CoA dehydrogenase deficiency cases detected by the New England Newborn Screening Program were classified according to initial and follow-up octanoylcarnitine values, octanoylcarnitine-decanoylcarnitine ratios, medium-chain acyl-CoA dehydrogenase genotype, follow-up biochemical parameters, and feeding by breast milk or formula. RESULTS. All 20 patients who were homozygous for 985A→G had high initial octanoylcarnitine values (7.0–36.8 μM) and octanoylcarnitine-decanoylcarnitine ratios (7.0–14.5), whereas the 27 patients with 0 to 1 copy of 985A→G exhibited a wide range of octanoylcarnitine values (0.5–28.6 μM) and octanoylcarnitine-decanoylcarnitine ratios (0.8–12.7). Initial newborn octanoylcarnitine values decreased by days 5 to 8, but the octanoylcarnitine-decanoylcarnitine ratio generally remained stable. Among 985A→G homozygotes, breastfed newborns had higher initial octanoylcarnitine values than newborns who received formula. Adverse events occurred in 5 children, 4 985A→G homozygotes and 1 compound heterozygote with a very high initial octanoylcarnitine: 2 survived severe neonatal hypoglycemia, 1 survived a severe hypoglycemic episode at 15 months of age, and 2 died as a result of medium-chain acyl-CoA dehydrogenase deficiency at ages 11 and 33 months. CONCLUSION. Newborn screening for medium-chain acyl-CoA dehydrogenase deficiency has detected cases with a wide range of genotypes and biochemical abnormalities. Although most children do well, adverse outcomes have not been entirely avoided. Assessment of potential risk and determination of appropriate treatment remain a challenge.

Newborn screening for hepatorenal tyrosinemia-I by tandem mass spectrometry using pooled samples: a four-year summary by the New England newborn screening program

OBJECTIVE The objective of this study is to develop an isotope dilution liquid chromatography tandem mass spectrometry assay to screen for hepatorenal tyrosinemia (HT) from newborn filter paper samples using pooled extracts to increase high throughput screening. DESIGN AND METHODS Succinylacetone (SUAC), the marker for HT, was extracted from dried blood spots with the formation of the hydrazone derivative of SUAC; up to eight sample extracts were pooled and the SUAC-derivative was analyzed by mass spectrometry methods with an injection-to-injection time of one minute. If any pooled sample extract screened positive, then the samples comprising the pooled sample were assayed individually. RESULTS Two newborn infants were identified with high levels of SUAC (7 & 23μM) and later confirmed to have HT. Three older children whose initial filter paper samples were taken at 195days to 614days of age with elevated SUAC (range 4.9-5μM) were identified; one of the three had clinical signs of HT and was placed on treatment (diagnosis of the other two are unavailable). CONCLUSION MS/MS analysis of pooled dried blood sample extracts permits sensitive, reduced instrumental analytical time and increase high throughput screening for HT.

A near-miss: very long chain acyl-CoA dehydrogenase deficiency with normal primary markers in the initial well-timed newborn screening specimen

To the Editor: Ficicioglu et al reported the first infant with very long chain acyl-CoA dehydrogenase deficiency (VLCADD) not detected by newborn screening performed within the ideal time frame. The experience of the New England Newborn Screening Program (NENSP) extends the number of VLCADD cases with a false-negative result and suggests that common interventions used in neonatal units might contribute to such errors. The initial specimen, collected from the infant on day of life (DOL)-2 (weight, 2420 g; gestational age, 34 weeks), screened normal. The values of VLCADD-specific markers C14:1 (0.34 mM) and C14:2 (0.12 mM) were below the NENSP cutoffs (0.70 mM and 0.17 mM, respectively), as well as the cutoffs of most other programs worldwide. A second specimen obtained on discharge from the special care nursery on DOL-9 was suggestive of VLCADD (C14:1, 0.82 mM; C14:2, 0.27 mM). A review of data for the initial specimen revealed that althoughmarkers were normal, the discriminator indices used by the NENSP to reflect a VLCADD profile when primary markers are abnormal were above their cutoffs. VLCADD was subsequently confirmed by diagnostic plasma acylcarnitine profiles and the detection of two pathogenic mutations on the VLCADD gene, 684G>A (A232T) and 848T>C (V283A). This neonate’s clinical history was notable for prematurity and initial poor oral intake, necessitating a hospital stay, but was otherwise unremarkable. The neonate received 10% dextrose intravenously from DOL-1 to DOL-5 and was then transitioned to oral feeds. We feel that dextrose, by suppressing fatty acid oxidation, might have masked the characteristic acylcarnitine accumulation. Our case underscores the fact that screening may fail to identify VLCADD and other disorders, especially in neonates receiving therapeutic interventions. Routine rescreening of such neonates at discharge in addition to the initial screen, even when the initial screen is normal, and analysis of biomarker profiles regardless of primary marker concentrations might reduce the risk of missing infants with these disorders.

Long-term follow-up to ensure quality care of individuals diagnosed with newborn screening conditions: early experience in New England.

To fulfill the purpose of newborn screening, comprehensive newborn screening programs must ensure that infants and children with newborn screening conditions are not only diagnosed but also they maintain engagement in appropriate lifespan and family-centered care for best outcomes. To ensure success, monitoring and care-coordination requires a systems-based approach to streamline the significant surveillance activities, which must not overburden the critical core functions of newborn screening nor the health care delivery system. Furthermore, treatment and care can only be improved by translating reliable knowledge into changes in practice, a process that requires evaluations of outcomes that are confirmable at the local level and translatable into a larger, e.g., national data set. We describe a sustainable public health systems approach to long-term follow-up, built on existing comprehensive newborn screening infrastructure and compatible with national endeavors. We also describe early experience with implementation of a centralized public-health tracking model and show that a significant proportion of cases detected through newborn screening do not continue with subspecialty care as they get older.