Georgia state spinal muscular atrophy newborn screening experience: Screening assay performance and early clinical outcomes.

The purpose of this study is to provide the results of the newborn screening (NBS) program for Spinal Muscular Atrophy (SMA) in the state of Georgia to determine disease incidence, time to diagnosis and treatment, and early outcomes. NBS for SMA was performed using real time PCR assays from February 2019 through February 2020 in a pilot phase of screening. This method continued as part of our official state panel, and here we describe the pilot period as well as the first year of standard screening through February 2021. Medical records of infants with a positive NBS were reviewed for time to confirmation and neurologic evaluation, SMN2 copy number, clinical information, and treatment. Descriptive statistics were applied. Of the 301,418 samples screened, there were 15 true positive (eight males) and 24 false positive cases. One patient was missed due to human error early in the pilot phase and presented after symptom onset. The incidence of SMA in Georgia is approximately 1 in 18,840 births per year. After the pilot phase, the false positive rate was found to be so low that all patients who test positive were immediately referred to neurology for further care. Four patients died prior to intervention. Ten patients received intervention. Gene therapy was the preferred treatment. One patient was lost to follow-up; another was clinically followed. In conclusion, trends for treated patients show improved or stable motor function. Long-term follow-up will help determine the durability of treatment.

Newborn Screening for X-Linked Adrenoleukodystrophy in Georgia: Experiences from a Pilot Study Screening of 51,081 Newborns.

We screened 51,081 newborns for X-linked adrenoleukodystrophy (ALD) using a two-tiered strategy quantifying very long chain lysophosphatadylcholines (LPC). Our testing strategy used flow injection tandem mass spectrometry for the first-tier analysis of LPCs, and second-tier quantification of C26:0 LPC using liquid chromatography tandem mass spectrometry. There were 364 specimens considered abnormal using our first-tier algorithm that relied on the four LPC measurements and post-analytical tools. Second-tier test results were reported as normal or abnormal based on a cutoff for the single analyte, C26:0 LPC. Eleven cases were reported as abnormal based on second-tier test results. One male with ALD was identified, and two females with peroxisomal biogenesis disorders were also identified. A single female case remains unresolved, due to a loss to follow up after a negative molecular test result for ABCD1 gene sequencing. The positive predictive value for confirmed, clinically relevant disorders during this pilot study was 27.3%. Challenges identified during the study period were based around coverage for confirmatory testing, particularly if family members needed molecular testing, which is an ongoing issue with newborn screening in Georgia. We also encountered issues with the follow up for a patient who remained asymptomatic. Due to the different timelines involved with clinical findings in ALD, follow-up coordination may be more difficult, particularly if the child identified by newborn screening (NBS) is the only member of the family affected, or able to be tested.

Two-Tiered Newborn Screening with Post-Analytical Tools for Pompe Disease and Mucopolysaccharidosis Type I Results in Performance Improvement and Future Direction.

We conducted a pilot newborn screening (NBS) study for Pompe disease (PD) and mucopolysaccharidosis type I (MPS I) in the multiethnic population of Georgia. We screened 59,332 infants using a two-tier strategy of flow injection tandem mass spectrometry (FIA-MSMS) enzyme assays. The first tier of testing was a 2-plex assay measuring PD and MPS I enzyme activity, followed by a second-tier test with additional enzymes to improve specificity. Interpretation of results was performed using post-analytical tools created using Collaborative Laboratory Integrated Reports (CLIR). We identified a single case of infantile onset PD, two cases of late onset PD, and one pseudodeficiency. The positive predictive value (PPV) for PD screening during the study was 66.7%. No cases of MPS I were identified during the study period, but there were 2 confirmed cases of pseudodeficiency and 6 cases lost to follow up. The two-tier screening strategy was successful in reducing false positive results and allowed for the identification and early treatment of a case of infantile PD but the frequency of pseudodeficiency in MPS I is problematic. Molecular testing is required and should be covered by the screening program to avoid delays in case resolution.

Increased parental anxiety and a benign clinical course: Infants identified with short-chain acyl-CoA dehydrogenase deficiency and isobutyryl-CoA dehydrogenase deficiency through newborn screening in Georgia.

The long-term consequences and need for therapy in children with short-chain acyl-CoA dehydrogenase deficiency (SCADD) or isobutyryl-CoA dehydrogenase deficiency (IBDD) identified via newborn screening (NBS) remains controversial. Initial clinical descriptions were severe; however, while most cases identified through NBS have remained asymptomatic, clinical concerns have been raised in these populations. It is not clear whether these children are asymptomatic because of the success of NBS, or because the normal clinical course of these disorders is relatively benign. To evaluate these possibilities in our program, we evaluated the clinical outcomes of children with SCADD or IBDD identified by the Georgia NBS compared to the health status of a healthy age-matched control group. We also assessed parental anxiety during a phone interview both subjectively and objectively using the Pediatric Inventory for Parents (PIP), a validated measure of illness-related parental stress. The general health of 52 SCADD and nine IBDD cases from 2007 to 2016 were compared to the general health of unaffected control children obtained through the Centers for Disease Control and Prevention (CDC) parent listserv. We also collected statements from parents who participated in a phone survey regarding events they experienced during and after their diagnostic process. Overall, the children with SCADD and IBDD had no major health problems. There was no significant difference in cognitive development (p = .207). We identified a slightly higher incidence of reported neonatal hypoglycemia in the SCADD group; two of these occurred in the context of maternal diabetes. All interviewed parents reported extreme anxiety during the diagnostic period and current feelings of uncertainty about their child's future. PIP scores for all six caregivers who responded to that portion of the survey were consistent with some degree of parental stress. The greatest reported stressor was the unknown long-term impact of the illness. All children with SCADD and IBDD had no significant long-term sequelae. The phone interviews revealed substantial parental anxiety about the identification and follow-up of SCADD and IBDD. Based on our findings, the anxiety parents experience may be unwarranted given that we see no disease-associated morbidity or mortality in these children. Consideration should be given to the removal of these conditions from NBS panels, or if that is not possible, clinicians could educate parents on the benign nature of these diagnoses and release them from follow-up without treatment.

Diagnosis and characterization of Hb C/Hb Iowa: a rare but easily misidentified compound heterozygous condition.

Hb Iowa is a rare hemoglobin (Hb) variant with a Gly --> Ala substitution at position 119 of beta-globin. It was previously reported only in an African American infant who was also heterozygous for Hb S [beta6(A3)Glu --> Val] and her mother (Hb A/Iowa). Here we describe the second report of Hb Iowa, the first in conjunction with Hb C [beta6(A3)Glu --> Lys]. The patient was an African American girl, originally diagnosed as homozygous Hb C during neonatal screening. When seen in our clinic, hematological data for both the child and her mother (Hb C trait) indicated mild anemia with slightly low mean corpuscular volume (MCV) but normal red blood cell (RBC) count. Analysis of blood from the child by capillary isoelectric focusing (cIEF) identified Hb C and an unknown Hb variant with an isoelectric point (pI) intermediate to that of Hbs F and A. The unknown variant was identified as Hb Iowa by DNA sequence analysis of the beta-globin gene (GGC --> GCC). Both reported cases of Hb Iowa indicated that there are no abnormal hematological manifestations associated with this rare Hb variant. In both cases, however, Hb Iowa was mistaken for Hb F during routine neonatal screening by high performance liquid chromatography (HPLC) and/or gel IEF. Neonatal misidentification of Hb Iowa led to misdiagnosis of sickle cell disease and Hb C disease, respectively. In our patient, Hb Iowa was also misidentified as Hb A at 2 years of age by a commercial reference laboratory using cellulose acetate and citrate agar gel electrophoresis. This led to an incorrect diagnosis of Hb C trait. These results show that commonly used analytical methods can easily misidentify Hb Iowa as Hbs F or A in neonates, or older individuals, resulting in incorrect identification of the Hb phenotype. We conclude that the presence of Hb Iowa, or other variants with similar pIs, should be considered in cases where the results of follow-up testing conflict with neonatal diagnosis of sickle cell or Hb C disease, or where clinical presentation does not agree with diagnosis of either homozygous or heterozygous Hb S or Hb C.