International Newborn Screening Practices for the Early Detection of Congenital Adrenal Hyperplasia.

INTRODUCTION: Newborn screening (NBS) programmes vary internationally in their approach to screening. Guidelines for congenital adrenal hyperplasia (CAH) screening recommend the use of two-tier testing and gestational age cutoffs to minimise false-positive results. The aims of this study were to describe (1) the approaches; (2) protocols used; and (3) available outcomes for CAH screening internationally. METHODS: All members of the International Society for Neonatal Screening were asked to describe their CAH NBS protocols, with an emphasis on the use of second-tier testing, 17-hydroxyprogesterone (17OHP) cutoffs, and gestational age and birth weight adjustments. If available, screening outcomes were requested. RESULTS: Representatives from 23 screening programmes provided data. Most (n = 14; 61%) recommend sampling at 48-72 h of life. Fourteen (61%) use single-tier testing and 9 have a two-tier testing protocol. Gestational age cutoffs are used in 10 programmes, birth weight cutoffs in 3, and a combination of both in 9. One programme does not use either method of adjusting 17OHP cutoffs. Case definition of a positive test and the response to a positive test differed between programmes. CONCLUSIONS: We have demonstrated significant variation across all aspects of NBS for CAH, including timing, the use of single versus two-tier testing and cutoff interpretation. Collaboration between international screening programmes and implementation of new techniques to improve screen efficacy will facilitate ongoing expansion and quality improvement in CAH NBS.

The presentation of congenital adrenal hyperplasia in an unscreened population.

BACKGROUND: The aim of this study was to describe the incidence and spectrum of early clinical presentations of congenital adrenal hyperplasia (CAH) in an unscreened population. METHODS: A national retrospective observational study was undertaken to identify all children diagnosed with CAH in the Republic of Ireland, between January 2005 and December 2019. Reporting clinicians completed anonymized clinical questionnaires. RESULTS: There were 103 cases of CAH reported and 69 cases met the study inclusion criteria. The estimated annualized incidence of CAH in the Republic of Ireland was 1:14,754 or 0.07 cases per 1,000 live births. Forty-seven children presented clinically in the first six months of life, but only 17 of these had a confirmed diagnosis by day 10. Of these early presentations, there were 28 infants with salt-wasting, 15 females presented with virilized genitalia and four infants were detected due to a family history of CAH. Female infants presented at a median age of 0 days [IQR 0-1] and males at 14 days [IQR 9-21]. Seventy-eight percent of salt-wasting presentations occurred after day 10. Delays in clinical presentation, biochemical diagnosis and treatment initiation were identified. CONCLUSIONS: The incidence of CAH is higher in Ireland than in other unscreened populations. In the absence of screening, clinicians should be aware of the possibility of CAH and appropriate investigations should be urgently requested. Life-threatening salt-wasting is the most frequent clinical presentation and many cases could be detected prior to decompensation if newborn screening were introduced.

Hypoglycemia is not a defining feature of metabolic crisis in mitochondrial 3-hydroxy-3-methylglutaryl-CoA synthase deficiency: Further evidence of specific biochemical markers which may aid diagnosis.

Mitochondrial 3-hydroxy-3-methylglutaryl-CoA (HMG Co-A) synthase (mHS) deficiency is an autosomal recessive disorder of ketone body synthesis which has traditionally been associated with hypoketotic hypoglycemia, hepatomegaly and encephalopathy, presenting in early childhood following a period of fasting. We report the third case of mHS deficiency presenting in the absence of hypoglycemia, with profound biochemical abnormalities and further evidence of potential specific diagnostic biomarkers. A previously well, 20-month old, unvaccinated male, of nonconsanguineous Polish heritage, presented with encephalopathy, hepatomegaly, severe metabolic acidosis, and mild hyperammonemia following a brief intercurrent illness. The patient was reported to have taken colloidal silver prior to presentation, posing a further diagnostic challenge. Additionally, he developed features suggestive of hemophagocytic lymphohistiocytosis during treatment. While the patient was normoglycemic prior to dextrose administration, the sample was markedly lipemic, with significant hypertriglyceridemia detected. Urine organic acid analysis revealed dicarboxylic aciduria with 4-hydroxy-6-methyl-2-pyrone (4HMP) and the presence of three other previously reported putative biomarkers for mHS deficiency. Glutarate was markedly elevated in the initial chromatogram, with a mild increase in 3-hydroxyglutarate (3HG) persisting. Raised acetylcarnitine was detected on acylcarnitine profile. Molecular genetic analysis of the HMGCS2 gene identified compound heterozygosity for known pathogenic mutations c.634G>A and c.1016+1G>A, confirming the diagnosis of mHS deficiency. This case provides further evidence that hypoglycemia is not invariably present in symptomatic mHS deficiency. We propose that elevated acetylcarnitine, triglycerides, and 3HG are additional biochemical features during acute presentations. With the expansion of novel biomarkers, further cases of this rare disorder may emerge.