Newborn screening for congenital adrenal hyperplasia in New Zealand

Implementing steroid profiling by liquid chromatography-tandem mass spectrometry improves newborn screening for congenital adrenal hyperplasia in New Zealand

OBJECTIVE

To evaluate the impact of a liquid chromatography-tandem mass spectrometry (LCMSMS) second-tier test on newborn screening for congenital adrenal hyperplasia due to 21-hydroxylase deficiency (CAH) in New Zealand.

DESIGN

In a prospective study, a LCMSMS method to measure 17-hydroxyprogesterone (17OHP) was adapted to measure four additional steroids. Steroid concentrations were collected on all second-tier CAH screening tests while protocols remained unchanged. Steroid ratio parameters with recommended or published screening cuts-offs were evaluated for their impact on newborn screening performance.

MEASUREMENTS

Precision, accuracy, linearity and recovery of the second-tier LCMSMS method were evaluated. Second-tier specimens were divided in 3 groups; newborn screening bloodspots from neonates with confirmed CAH (n = 7) and 2 groups specimens from neonates with a birthweight (BW) ≤1500 g (n = 795) and with a BW > 1500 g (n = 806) with a negative newborn screening test. Six protocols using four steroid ratio parameters were evaluated. The sensitivity, specificity, false positive rate and positive predictive value of screening was calculated for each protocol.

RESULTS

The LCMSMS method was sufficiently accurate and precise to be used as a second-tier test for CAH. Screening sensitivity remained at 100% for each protocol apart from (17OHP + androstenedione)/cortisol when the highest cut-off of 3.75 was applied. The false positive rate was significantly improved when (17OHP + androstenedione)/cortisol and (17OHP + 21-deoxycortisol)/cortisol were evaluated with cut-offs of 2.5 and 1.5 respectively (P < .01) and both with a positive predictive value of 64%.

CONCLUSIONS

A second-tier LCMSMS newborn screening test for CAH offers significant improvements to screening specificity without any other changes to screening protocols.

Challenges in Assessing the Cost-Effectiveness of Newborn Screening: The Example of Congenital Adrenal Hyperplasia

Generalizing about the cost-effectiveness of newborn screening (NBS) is difficult due to the heterogeneity of disorders included in NBS panels, along with data limitations. Furthermore, it is unclear to what extent evidence about cost-effectiveness should influence decisions to screen for specific disorders. Screening newborns for congenital adrenal hyperplasia (CAH) due to 21-hydroxylase deficiency can serve as a useful test case, since there is no global consensus on whether CAH should be part of NBS panels. Published and unpublished cost-effectiveness analyses of CAH screening have yielded mixed findings, largely due to differences in methods and data sources for estimating health outcomes and associated costs of early versus late diagnosis as well as between-country differences. Understanding these methodological challenges can help inform future analyses and could also help interested policymakers interpret the results of economic evaluations.

Newborn screening for congenital adrenal hyperplasia in New Zealand, 1994-2013

OBJECTIVE

The objective of the study was to evaluate the efficacy of national newborn screening for severe congenital adrenal hyperplasia (CAH) in New Zealand over the past 20 years.

METHODS

Newborn screening for CAH is performed through the estimation of 17-hydroxyprogesterone by a Delfia immunoassay. CAH cases diagnosed in the newborn period from 1994 to 2013 were identified from Newborn Metabolic Screening Programme records.

RESULTS

Between 1994 and 2013, 44 neonates (28 females, 16 males) were diagnosed with CAH, giving an incidence of 1:26 727. Almost half (n = 21) of the newborns with CAH were detected solely via screening (not clinically suspected), including 21% of all affected females. Among the group solely ascertained by screening, 17-hydroxyprogesterone sampling occurred at a mean age of 3.3 days (range 2-8 d), the duration from sampling to notification was 5.2 days (0-12 d), and treatment was initiated at 12.0 days (6-122 d). Vomiting was present in 14% of those ascertained by screening, but none had hypotension or collapse at diagnosis. Increasing age at treatment was correlated with a progressive decrease in serum sodium (r = -0.56; P < .0001) and an increase in serum potassium concentrations (r = 0.38; P = .017). Compared with newborns diagnosed by screening alone, those clinically diagnosed were predominantly female (96% vs 29%; P < .0001), notification occurred earlier (4.8 vs 8.5 d; P = .002), and had higher serum sodium (136.8 vs 130.8 mmol/L; P < .0001) and lower serum potassium (5.3 vs 6.0 mmol/L; P = .011) concentrations.

CONCLUSIONS

Screening alone accounted for nearly 50% cases of CAH detected in the newborn period, including a fifth of affected females, indicating that clinical diagnosis is unreliable in both genders. Symptoms were mild at diagnosis and there were no adrenal crises. This study confirms the benefits of newborn CAH screening.

Newborn screening for congenital adrenal hyperplasia in Cuba: six years of experience

BACKGROUND

Since 2005, a newborn screening program for congenital adrenal hyperplasia (CAH) by measuring 17-alpha-hydroxyprogesterone (17OHP) in dried blood spots was introduced in Cuba.

METHODS

The hormone was measured by the 17OHP Neonatal UMELISA method, in samples collected on the 5th day as average. Confirmatory test was performed to those neonates with 17OHP values above 55 nmol/l. Some perinatal factors that can influence on 17OHP levels were studied.

RESULTS

From January 2005 to December 2010, 621,303 newborns were screened and 39 CAH cases were detected. Coverage of the program reached 98%. The incidence of CAH in Cuba was 1:15,931, similar to that reported by other programs. A recall for suspected CAH was performed in 10,799 cases (1.74%). Therapy in classical CAH patients was started at the mean age of 22 days. 17OHP levels were significantly higher in newborns with lower birth-weight (BW) and/or gestational age (GA). In addition, 17OHP values were affected by the gender, twin status or mode of delivery.

CONCLUSIONS

In Cuba, the nationwide newborn screening program has allowed the early detection of CAH. The use of an optimized cut-off level for BW or GA could lead to a reduction in the percentage of recalled babies.

An unusual case of secondary amenorrhoea

A 22-year-old married woman presented with complaints of amenorrhoea and masculinisation. She had hoarseness of voice, hirsutism and ambiguous genitalia. Uterus, cervix and vagina were normal. Investigations revealed a high testosterone level, insignificant luteinizing hormone/follicle stimulating hormone (LH/FSH) and a raised 17-OH progesterone level. Ultrasonography revealed no ovarian or adrenal mass. A diagnosis of 21-hydroxylase deficient classic congenital adrenal hyperplasia, simple virilising form was considered. She was put on prednisolone and given oral contraceptive pill containing cyproterone acetate. Her testosterone level decreased and spontaneous menstruation started. She desired conception and ovulation was induced with clomiphene citrate. She conceived in the second menstrual cycle on clomiphene 50 mg. Imaging at 6 weeks revealed a viable fetus, and an anomaly scan at 16 weeks showed a healthy fetus. However, unfortunately, she aborted around 21 weeks. A scan immediately prior to abortion revealed a subchorionic haematoma.

Ethnic and gender differences in rates of congenital adrenal hyperplasia in Western Australia over a 21 year period

AIM

To evaluate the incidence, sex distribution, ethnicity, age at diagnosis, clinical presentation and morbidity of all childhood-onset congenital adrenal hyperplasia (CAH) cases in Western Australia (WA) between 1990 and 2010, a state where newborn screening for CAH is not in place.

METHODS

The total number of all known CAH cases was identified. Case files were reviewed retrospectively to determine clinical details. Classical CAH (C-CAH) was defined as patients presenting before 6 months of age and non-classical (NC-CAH) as presenting after 6 months.

RESULTS

Of the 41 CAH cases (26 female) born in WA, 5(12.2%) were of Aboriginal ethnicity. CAH was due to 21-hydroxylase deficiency in 40 cases. Of those with 21-hydroxylase deficiency, 37 were C-CAH (25 female) and 3 NC-CAH (all male). The incidence of C-CAH in WA was estimated to be 0.67 per 10, 000 live births (1:14, 869). The incidence rate ratio of Aboriginal compared with non-Aboriginal C-CAH was 2.45 (95% confidence interval 0.96-6.29). The mean age of diagnosis of C-CAH cases was lower in females (8.9 ± 2.5 days) compared to males (23.4 ± 9.8 days). Among these males, 72.7% presented initially with adrenal crisis.

CONCLUSION

The estimated incidence of classical CAH is similar to composite worldwide data. The increased female-to-male ratio is not in keeping with the expected sex distribution seen in a recessively inherited disease. The delayed diagnosis in males, with a significant proportion presenting with adrenal crisis, could be avoided with newborn screening. The higher rate of CAH in patients with Aboriginal ethnicity is a novel observation.

Development of an indirect enzyme immunoassay using monoclonal antibodies for the measurement of 17alpha-hydroxyprogesterone in human serum

An indirect enzyme immunoassay for the measurement of total 17alpha-hydroxyprogesterone (17OHP) in serum using monoclonal antibodies generated in our laboratory was developed. Here, (a) instead of extraction with solvents, serum was heated to free protein-bound 17OHP and assay was performed at pH 9.6, (b) to ensure uniform assay conditions for both standards and samples, buffer for standards contained charcoal-stripped pre-heated pooled cord serum. Assays were done in 96-well EIA microplates pre-coated with 17alpha-hydroxyprogesterone-3-(o-carboxymethyl)oxime: bovine serum albumin. Secondary antibody was horseradish peroxidase-linked sheep anti-mouse IgG polyclonal antibody. The method was accurate and suitable for screening for congenital adrenal hyperplasia.

CYP21A2 gene mutations in congenital adrenal hyperplasia: genotype-phenotype correlation in Turkish children

BACKGROUND

Congenital adrenal hyperplasia (CAH) due 21-hydroxylase deficiency (21-OHD) is a common autosomal recessive disorder. It is caused by defects in the CYP21A2 gene.

OBJECTIVE

Our aim was to determine the frequency of common gene mutations and to evaluate genotype-phenotype correlations in Turkish 21-OHD patients.

METHODS

Molecular analysis of the CYP21A2 gene was performed for the detection of the eight most common point mutations [p.P30L, IVS2-13C>G (IVS-2), p.I172N, exon 6 mutation cluster (p.I236N, p.V237E, p.M239K), p.V281L, p.Q318X, p.R356W, 8-bp-deletion], of large deletion and conversion by southern blotting, allele specific semi-quantitative PCR/enzyme restriction method and sequencing, in 56 patients with 21-OHD, from 52 families.

RESULTS

Disease-causing mutations were identified in 77 out of 91 alleles (84.6%) of the patients. Mutations were found in 34 of 43 alleles (79.1%) in salt wasting (SW; n=26), 32 of 36 alleles (88.8%) in simple virilizing (SV; n=24) and 11 of 12 alleles (91.6%) in non-classical (NC; n=6) form of CAH. The most frequent mutations were IVS-2 (22.0%), large conversion (14.3%), p.I172N (9.9%) p.R356W (8.8%), and large deletion (6.6%). In the SW form, the most frequent genotypes were homozygous for IVS-2 (11.5%) and homozygous for large conversion of the gene (11.5%). In the SV form, the most frequent genotype was homozygous for IVS-2 (20%), followed by compound heterozygous for p.I172N/8-bp del (10%). Homozygous for p.V281L (16.7%) was most common in NC. In most cases there was good correlation between genotype and phenotype. In the SW and NC forms, genotypes of all the patients correlated with their phenotypes.

CONCLUSIONS

This is the first comprehensive study on the molecular basis of CAH patients in the Turkish population. Based on these results, we propose a modified screening strategy to facilitate molecular testing of CAH patients in our population.

Two-year pilot study of newborn screening for congenital adrenal hyperplasia in New South Wales compared with nationwide case surveillance in Australia

AIM

To assess the benefits and practicalities of setting up a newborn screening (NBS) program in Australia for congenital adrenal hyperplasia (CAH) through a 2 year pilot screening in ACT/NSW and comparing with case surveillance in other states.

METHODS

The pilot newborn screening occurred between 1/10/95 and 30/9/97 in NSW/ACT. Concurrently, case reporting for all new CAH cases occurred through the Australian Paediatric Surveillance Unit (APSU) across Australia. Details of clinical presentation, re-sampling and laboratory performance were assessed.

RESULTS

185,854 newborn infants were screened for CAH in NSW/ACT. Concurrently, 30 cases of CAH were reported to APSU, twelve of which were from NSW/ACT. CAH incidence was 1 in 15 488 (screened population) vs 1 in 18,034 births (unscreened) (difference not significant). Median age of initial notification was day 8 with confirmed diagnosis at 13(5-23) days in the screened population vs 16(7-37) days in the unscreened population (not significant). Of the 5 clinically unsuspected males in the screened population, one had mild salt-wasting by the time of notification, compared with salt-wasting crisis in all 6 males from the unscreened population. 96% of results were reported by day 10. Resampling was requested in 637 (0.4%) and median re-sampling delay was 11(0-28) days with higher resample rates in males (p < 0.0001). The within-laboratory cost per case of clinically unsuspected cases was A$42 717.

CONCLUSION

There seems good justification for NBS for CAH based on clear prevention of salt-wasting crises and their potential long-term consequences. Also, prospects exist for enhancing screening performance.

Incidence of classical 21-hydroxylase deficiency and distribution of CYP21A2 mutations in Estonia

AIMS

To determine the incidence of classical 21-hydroxylase deficiency (21-OHD) in Estonia from 1978 to 2004, and describe their phenotype and genotype.

METHODS

All Estonian endocrinologists informed us about their patients with 21-OHD. The diagnosis was confirmed in 20 patients, who were all screened for 8 common mutations of the CYP21A2 gene.

RESULTS

The 27-year period incidence was 1:25,500. The incidence from 1992 was 1:16,100, which more accurately reflects the real situation in Estonia. The salt-wasting form (SW) was diagnosed in 14 (7 males) and the simple virilizing form in 6 patients (1 male). The median age at diagnosis of the SW form was 30 days in males and 2 days in females. The investigation of 34 unrelated alleles showed that a common deletion/conversion was the most frequent mutation in our group (7/34). Six other mutations were present: p.Ile172Asn (5/34), 8-bp deletion (3/34), intron-2 splice mutation (3/34), p.Arg356Trp (3/34), p.Gln318X (3/34) and a small conversion (2/34). Mutations in 8 alleles remained uncertain.

CONCLUSIONS

The incidence of classical 21-OHD in Estonia in 1992-2004 was 1:16,100. The genotype of our patients is similar to those from other Caucasian populations. The relatively late age at diagnosis and the skewed female:male ratio supports the need for newborn screening for 21-OHD.

Neonatal screening for congenital adrenal hyperplasia: experience and results in Argentina

AIM

To report the experience of the neonatal screening program for congenital adrenal hyperplasia (CAH) carried out in Buenos Aires, Argentina, from 1997 to 2006.

POPULATION AND METHODS

17-Hydroxyprogesterone (17OHP) was measured with an immunofluorometric assay in filter paper blood samples collected at neonatal maternity discharge. Filter paper blood levels <40 nmol/l were considered normal. 17OHP levels from 40-90 nmol/l triggered a new assessment to decide on a course of action. Confirmation of CAH was made with levels >90 nmol/l. This led to clinical follow up. For preterm (PT) infants, data were adjusted according to percentiles for gestational age and/or birth weight.

RESULTS

From 80,436 screened newborns (46.8% girls), 8848 (11%) were PT. 15 term (T) and 3 PT infants were recalled (0.022%). Nine were confirmed as having CAH (8 T and 1 PT) (female/male: 0.8; incidence 1:8937). Mean ages of screening and treatment were 5.7 and 13 days. Only 33% of affected children were clinically suspected of having CAH prior to screening. Four boys and two girls presented salt-wasting forms and severe adrenal insufficiency crises were prevented as a result of the screening.

CONCLUSIONS

Our findings confirm the benefits of CAH neonatal screening in our country with a high incidence of the classical form. Established criteria of screening and follow up allowed us to detect unrecognized affected males and females and to successfully prevent salt-wasting crises.

Ethnic-specific distribution of mutations in 716 patients with congenital adrenal hyperplasia owing to 21-hydroxylase deficiency

Congenital adrenal hyperplasia (CAH) due to 21-hydroxylase deficiency (21OHD) occurs worldwide. The most common mutations in the CYP21A2 gene in 716 unrelated patients were analyzed and the mutations were grouped by ethnicity, as defined through self-declaration corroborated by review of pedigrees extending to two or three generations. Prevalent allelic mutations and genotypes were found to vary significantly among ethnic groups, and the predominance of the prevalent mutations and genotypes in several of these populations was significant. There are ethnic-specific mutations in the CYP21A2 gene. A large deletion is prevalent in the Anglo-Saxons; a V281L (1685 G to T) mutation is prevalent in Ashkenazi Jews; an R356W (2109 G to A) mutation is prevalent in the Croatians; an IVS2 AS -13 (A/C to G) mutation is prevalent in the Iranians and Yupik-speaking Eskimos of Western Alaska; and a Q318X (1994 C to T) mutation is prevalent in East Indians. Genotype/phenotype non-correlation was seen when at least one IVS2 AS -13 (A/C to G) mutation in the CYP21A2 gene was present.

How many deaths can be prevented by newborn screening for congenital adrenal hyperplasia?

BACKGROUND/AIMS

Congenital adrenal hyperplasia (CAH) is increasingly being included in newborn screening programs. Screening can prevent neonatal mortality in children with salt-wasting CAH, but the number of deaths prevented is not known. Cost-effectiveness analyses of screening require estimates of the probability of mortality in CAH.

METHODS

We reviewed the literature to identify cohort studies of children with CAH ascertained clinically in the absence of screening. We abstracted the numbers of infant deaths attributable to CAH. We also addressed sex ratios among children with clinically detected CAH and the contribution of ascertainment bias to unbalanced ratios.

RESULTS

The evidence suggests a probability of infant death due to adrenal crises in salt-wasting CAH of 4% or less in contemporary advanced economies without screening for CAH. This is lower than previous estimates, although the rate of mortality could be considerably higher in populations with limited clinical awareness or access.

CONCLUSION

Although screening for CAH is conducted in a number of countries, further research is still needed to provide reliable estimates on the numbers of prevented deaths, along with evidence-based assessments of the potential benefits, harms, and costs of screening.

Diagnosis and management of congenital adrenal hyperplasia

Congenital adrenal hyperplasia is the name applied to a class of autosomal recessive disorders resulting from deficiency of one of five enzymes necessary for cortisol synthesis by the adrenal cortex. Congenital adrenal hyperplasia is most often attributable to steroid 21-hydroxylase deficiency, accounting for more than 90% of cases. This discussion will be limited to the most common form of the disease, highlighting methods of diagnostic screening and challenges in disease management.

Newborn screening for congenital adrenal hyperplasia has reduced sensitivity in girls

OBJECTIVES

To characterize Wisconsin-born infants with 21-hydroxylase deficiency-congenital adrenal hyperplasia (21-OH-D-CAH) who were not identified by the newborn screening for 21-OH-D-CAH, and to examine male and female screening 17-hydroxyprogesterone (17-OHP) levels.

STUDY DESIGN

Information on infants with false-negative results was gathered. Results of the Wisconsin newborn screening for 21-OH-D-CAH from January 1, 2000, to June 30, 2003, were analyzed to detect possible differences between male (n=119,842) and female (n=114,951) infants.

RESULTS

Six of 7 female infants with false-negative results had genital masculinization, and 4 of 8 infants with false-negative results had laboratory evidence of salt-wasting. None died, had a salt-wasting crisis, or was assigned the wrong sex. A significant difference in the mean 17-OHP levels between male (17.5 ng/mL) and female (15.4 ng/mL) infants (P <.0001) was detected. The sensitivity of newborn screening for female infants was 60%, compared with 80% for male infants.

CONCLUSIONS

Male and female infants have significantly different mean 17-OHP levels on newborn screening, and female infants comprise most of the infants with false-negative results. Although health professionals should not assume that newborn screening for 21-OH-D-CAH is a means of identifying all affected infants, the primary goals of newborn screening for CAH (prevention of salt-wasting crises and sex misassignment) are fulfilled.

Cutoff levels of 17-alpha-hydroxyprogesterone in neonatal screening for congenital adrenal hyperplasia should be based on gestational age rather than on birth weight

OBJECTIVE

In newborn screening programs for congenital adrenal hyperplasia, 17-alpha-hydroxyprogesterone (17OHP) cutoff levels are based on birth weight (BW) or on gestational age (GA). We investigated which approach would result in the greatest specificity and sensitivity.

STUDY DESIGN

For the determination of 17OHP, a neonatal 17OHP assay was used in filter paper blood of 9492 newborns. The relationships between 17OHP and BW and between 17OHP and GA were studied by regression analysis. Reference curves with a specificity of 99.95% were constructed with the method that summarizes the distribution by three smoothed curves representing the skewness (L curve), the median (M curve), and the coefficient of variation (S curve). Median cutoff levels for BW and for GA according to the 99.95% reference curves were calculated.

RESULTS

Regression analysis showed that GA is a better predictor of 17OHP than BW (R(2) was 50.6 vs. 35.8%, respectively). At a specificity of 99.95%, the calculated median 17OHP cutoff level was lower for GA [12.6 microg/liter (38 nmol/liter)] than for BW [17.6 microg/liter (54 nmol/liter)], thus leading to a greater sensitivity.

CONCLUSION

This study demonstrates that GA is a better predictor of 17OHP in newborns and will result in greater specificity than BW despite the fact that the determination of GA might be less reliable than BW.

Triagem neonatal para hiperplasia adrenal congênita: experiência do estado do Rio de Janeiro

OBJETIVO: Descrever a distribuição das concentrações de 17OH Progesterona (17OHP) na triagem neonatal para pesquisa de Hiperplasia Adrenal Congênita por deficiência da 21hidroxilase (HAC-D21OH). CASUÍSTICA E MÉTODO: Análise da 17OHP por método imunofluorimétrico em 76.360 amostras de sangue colhido em papel filtro no período de junho de 1992 a dezembro de 2000 no Estado do Rio de Janeiro. O valor de corte foi definido em 10ng/mL e os casos com resultados acima deste valor eram chamados para nova coleta. RESULTADOS: Foram reconvocados 38 casos para nova coleta, sendo confirmados 11 casos com a forma clássica da HAC-D21OH (4 do sexo masculino, 6 feminino e 1 indeterminado), com valores de 17OHP na primeira amostra variando de 25 a 254,5ng/mL (média de 133ng/mL) e na segunda amostra de 45,86 a 360ng/mL (média de 218,84ng/mL). Os pacientes com a forma perdedora de sal apresentaram concentrações mais elevadas que os com a forma virilizante simples, tanto na primeira amostra (média de 169,21 contra 27,46ng/mL) quanto na segunda (média de 227,16 versus 110,95ng/mL). As concentrções de 17OHP nos 27 casos não confirmados (falso-positivos) variaram de 10,27 a 27,50ng/mL (média de 14,80ng/mL) na primeira amostra e de 2,39 a 32,39ng/mL (média 10,07ng/mL) na segunda amostra. Oito mantiveram concentrações de 17OHP moderadamente elevadas, sendo que normalizaram no decorrer do primeiro ano de vida em 7 casos, e em 1 paciente, apesar de assintomático, manteve valores elevados de 17OHP durante o acompanhamento de oito anos, com teste de estímulo com ACTH compatível com a forma não clássica da HCA-D21OH. CONCLUSÃO: A dosagem da 17OHP foi um método eficaz para a triagem da HAC-D21OH sendo capaz de discriminar as crianças normais daquelas acometidas pela forma clássica da doença.

Female preponderance in congenital adrenal hyperplasia due to CYP21 deficiency in England: implications for neonatal screening

Congenital adrenal hyperplasia (CAH) due to 21-hydroxylase (CYP21) deficiency causes symptoms ranging from life-threatening neonatal adrenal crises to minimal virilization in adulthood. The relationship between CYP21 genotype and phenotypic markers in a non-screened population of 73 CAH children (44 female, 29 male; 54 white, 19 Asian) treated at the Royal Manchester Children's Hospital was investigated and ethnic and sex differences assessed. The patients were categorized according to the mutation on the mildest allele. The age at the time of diagnosis differed significantly between the groups (p = 0.02): all 25 Null and 25 of 26 of the I2 splice patients were diagnosed during the neonatal period, whereas 7 of 11 I172N patients were diagnosed late. Degree of female genital virilization, 17-hydroxyprogesterone level at diagnosis, and fludrocortisone requirement during the 1st year of treatment correlated with the genotype, although Asian Null patients required more fludrocortisone than their white counterparts (p = 0.055). There was an equal sex ratio in both the I2 splice (12 female/14 male) and I172N (5 female/6 male) groups. However, in the Null group, the ratio was 4.0 (20 female/5 male; p = 0.003), suggesting that some Null male infants perish before being clinically detected to have CYP21 deficiency. Our findings strongly support the need for implementation of a neonatal screening programme for CAH in the UK which may reduce the male infant mortality.

Gene conversion (655G splicing mutation) and the founder effect (Gln318Stop) contribute to the most frequent severe point mutations in congenital adrenal hyperplasia (21-hydroxylase deficiency) in the Spanish population

This study addresses the contributions of gene conversion and a founder effect to the distribution of the two most frequent severe point mutations of the 21-hydroxylase (21OH) gene causing congenital adrenal hyperplasia: the 655G splicing mutation at intron 2, and Gln318Stop in a Spanish population. Direct and indirect analyses of segregated mutant and normal 21OH genes in 200 Spanish families (classic and nonclassic 21OH deficiency) were performed. Both mechanisms were found to contribute to different degrees to the defective investigated alleles. The 655G splicing mutation (62 alleles, 15.5%) seemed to be almost exclusively related to recent conversion events, whereas Gln318Stop (33 alleles, 8.3%) is more likely to be due to the dissemination of remotely generated mutant alleles. Other severe defective alleles, 8 bp-deletion (13 alleles, 3.3%), 306insT (5 alleles, 1.3%), and gene deletions (43 alleles, 11%), as well as the mild mutation Val281Leu (120 alleles, 30%), also appear to be strongly associated with particular D6S273 alleles. Although gene conversion contributes to the generation of severe 21OH alleles, the high frequency of some severe mutations in different geographic areas is consistent with a founder effect.

Epidemiology of 21-hydroxylase deficiency in Singapore

We report the incidence and epidemiology of 21-hydroxylase deficiency in Singapore, based on a retrospective study of all known patients diagnosed with classical 21-hydroxylase deficiency in the past 21 years. The database was obtained from the case registry and questionnaire methodology, with 100% coverage of all practising pediatricians in Singapore. There were 42 patients affected with 21-hydroxylase deficiency in 964,558 live births over 21 years, comprising 64.3% salt wasters and 35.7% simple virilizers, of whom 50.0% were males and 50.0% females. The incidence of classical 21-hydroxylase deficiency is 4.5 per 100,000 live births, with a carrier frequency of 1:76, and a gene frequency of 0.0067. Although retrospective studies have inherent limitations, the gender and phenotype ratios suggest that the data provide a crude incidence level. This study underscores the necessity for prospective neonatal screening, so that the benefits of early diagnosis and treatment can be realized.

Congenital adrenal hyperplasia: epidemiology, management and practical drug treatment

Congenital adrenal hyperplasia (CAH) owing to 21-hydroxylase deficiency is a common disorder, and is characterised by a defect in cortisol biosynthesis with or without a defect in aldosterone synthesis and androgen excess. The classic form, also known as the severe form, occurs in 1:15,000 births worldwide, while the nonclassic or mild form occurs in approximately 1:1,000 births worldwide and is much more common (up to 1:20) in certain ethnic groups. In classic 21-hydroxylase deficiency, glucocorticoids are given in doses sufficient to suppress adrenal androgen secretion, and mineralocorticoids are given to normalise electrolytes and plasma renin activity. The management of CAH may be complicated by iatrogenic Cushing's syndrome, inadequately treated hyperandrogenism, or both. Prenatal treatment may decrease virilisation of the affected female foetus, but the efficacy and safety of treating CAH prenatally remains to be fully defined. Close clinical monitoring of growth and development is essential to optimise treatment outcome. New treatment approaches are currently under investigation in the most severely affected patients, while nonclassic CAH does not always require treatment.

Neonatal screening for congenital adrenal hyperplasia: 17-hydroxyprogesterone levels and CYP21 genotypes in preterm infants

OBJECTIVE

Neonatal screening for congenital adrenal hyperplasia (CAH) among preterm infants is complicated by the fact that healthy preterm infants have higher levels of 17-hydroxyprogesterone (17-OHP) than term infants, resulting in a higher false-positive rate. Even when gestational age-related cutoff levels after ether extraction were used, the false-positive cases primarily comprised preterm infants. The aim of the study was to optimize the procedure for neonatal screening for CAH in preterm infants.

METHODS

The 17-OHP levels in 6200 preterm infants were correlated to the gestational age. We also calculated the number of recalls for different putative cutoff levels of the 17-OHP by direct assay and after extraction in 1275 preterm infants who represented the most elevated cases in a population of approximately 30 000 preterm infants. The CYP21 genotypes and screening levels were determined in the 12 preterm infants with CAH diagnosed since the start of screening. The effect of possible interfering factors such as gestational age, neonatal stress, and prenatal glucocorticoid treatment for pulmonary maturation was studied.

RESULTS

The extraction procedure did not significantly improve the sensitivity or specificity of the screening, whereas it delayed the day of recall from 8 to 13 days (median). We could not demonstrate any systematic influence of the studied stress factors or the prenatal glucocorticoid treatment on the 17-OHP screening levels. In the patients with CAH, the 17-OHP levels correlated better with disease severity than with the degree of prematurity.

CONCLUSIONS

On the basis of these results, we omitted the extraction step and changed the cutoff levels in the Swedish screening program for preterm infants. We chose to use a cutoff level of 400 nmol/L plasma in infants who were born before week 35 and 150 nmol/L for infants who were born in weeks 35 and 36. For detecting more patients, the cutoff level would have to be much lower, which would result in a number of false-positive tests that we consider to be unacceptably high. It is clear that neonatal screening cannot detect all infants with CAH. Some milder forms of the disease, just like in the past, will have to be diagnosed on the basis of clinical signs and symptoms.

Methodological issues in newborn screening evaluation with special reference to congenital adrenal hyperplasia

Evidence-based evaluation of newborn screening is essential because of the increasing number of genetic tests, the mandatory nature of newborn screening in the United States, and the growing cost to the public to maintain expensive screening programs. This paper discusses the methodological problems that arise when applying universally accepted criteria to disorders such as congenital adrenal hyperplasia. These problems include the tendency of screening to alter the natural history of the disease, the lack of consensus about terms and definitions, and the paucity of longitudinal studies on screen detected neonates. In order to evaluate and compare candidate screens we recommend formal national trials of promising programs, with defined responsibility of state agencies, physicians, patients, and insurers for data submission and analysis.

Congenital adrenal hyperplasia due to 21-hydroxylase deficiency

More than 90% of cases of congenital adrenal hyperplasia (CAH, the inherited inability to synthesize cortisol) are caused by 21-hydroxylase deficiency. Females with severe, classic 21-hydroxylase deficiency are exposed to excess androgens prenatally and are born with virilized external genitalia. Most patients cannot synthesize sufficient aldosterone to maintain sodium balance and may develop potentially fatal "salt wasting" crises if not treated. The disease is caused by mutations in the CYP21 gene encoding the steroid 21-hydroxylase enzyme. More than 90% of these mutations result from intergenic recombinations between CYP21 and the closely linked CYP21P pseudogene. Approximately 20% are gene deletions due to unequal crossing over during meiosis, whereas the remainder are gene conversions--transfers to CYP21 of deleterious mutations normally present in CYP21P. The degree to which each mutation compromises enzymatic activity is strongly correlated with the clinical severity of the disease in patients carrying it. Prenatal diagnosis by direct mutation detection permits prenatal treatment of affected females to minimize genital virilization. Neonatal screening by hormonal methods identifies affected children before salt wasting crises develop, reducing mortality from this condition. Glucocorticoid and mineralocorticoid replacement are the mainstays of treatment, but more rational dosing and additional therapies are being developed.

How sexually dimorphic are we? Review and synthesis

The belief that Homo sapiens is absolutely dimorphic with the respect to sex chromosome composition, gonadal structure, hormone levels, and the structure of the internal genital duct systems and external genitalia, derives from the platonic ideal that for each sex there is a single, universally correct developmental pathway and outcome. We surveyed the medical literature from 1955 to the present for studies of the frequency of deviation from the ideal male or female. We conclude that this frequency may be as high as 2% of live births. The frequency of individuals receiving "corrective" genital surgery, however, probably runs between 1 and 2 per 1,000 live births (0.1-0.2%). Am. J. Hum. Biol. 12:151-166, 2000. Copyright 2000 Wiley-Liss, Inc.

How sexually dimorphic are we? Review and synthesis

The belief that Homo sapiens is absolutely dimorphic with the respect to sex chromosome composition, gonadal structure, hormone levels, and the structure of the internal genital duct systems and external genitalia, derives from the platonic ideal that for each sex there is a single, universally correct developmental pathway and outcome. We surveyed the medical literature from 1955 to the present for studies of the frequency of deviation from the ideal male or female. We conclude that this frequency may be as high as 2% of live births. The frequency of individuals receiving "corrective" genital surgery, however, probably runs between 1 and 2 per 1,000 live births (0.1-0.2%). Am. J. Hum. Biol. 12:151-166, 2000. Copyright 2000 Wiley-Liss, Inc.

Virilising 21-hydroxylase deficiency: timing of newborn screening and confirmatory tests can be crucial

Early diagnosis of congenital adrenal hyperplasia (CAH) can be lifesaving. With the advent of newborn screening programs employing blood 17-hydroxyprogesterone, fewer cases are missed. Because false positive results occur, especially in premature and low birth weight babies, infants with borderline elevations, although requiring follow-up, are often considered normal. We describe a newborn female that, despite severe virilization, only had a borderline elevation in 17-hydroxyprogesterone (17OHP) on newborn screening, as well as on initial confirmatory testing in our clinical laboratory. Our confirmatory method, which employs high performance liquid chromatography (HPLC) separation, because of its high specificity, yields steroid values from both normal children and those with CAH that are lower than found with older, less specific methods. Given the heterogeneity of phenotypes of CAH, less severe forms, especially in males, could result in marginally abnormal laboratory results early in life, with possible adverse effects later. Although in retrospect the diagnosis of the described patient was clear and not a novel entity, we consider it an important example for several reasons. It emphasizes the broad range of 17OHP levels in CAH, the lack of correlation of these levels with clinical phenotype and the importance of the timing of both screening and confirmatory tests. Due to the complexity of interpreting these tests, any screening program for CAH should be controlled by an experienced pediatric endocrinologist.

Longitudinal measurements of 17alpha-hydroxyprogesterone in premature infants during the first three months of life

AIMS

To determine normal concentrations of 17alpha-hydroxyprogesterone (17OHP) for premature infants.

METHODS

17OHP was measured in 66 consecutive premature infants once a week during the first month, and once every two weeks thereafter, until the age of 3 months. The 17OHP values in 100 full term healthy neonates on the third day of life served as controls. Blood was sampled on filter paper using a neonatal radioimmunoassay kit. Findings were correlated with gestational age, birthweight, mode of delivery, Apgar scores, presence of respiratory distress syndrome and intake of maternal steroids.

RESULTS

Mean 17OHP was raised at 7 days of age (138.9, 46.3, 53.3, 29.9 nmol/l, respectively, for infants whose gestational age was under 29 weeks, 29 to 30 weeks, 31 to 32 weeks, and 33 weeks and above). It fell sharply in the first two weeks after which it gradually decreased further, reaching 32.7, 23.6, 16.9, and 13.0 nmol/l, respectively, by the age of 90 days. The mean (SEM) 17OHP concentration in full term infants on day 3 of life was 17.8 (8.9) nmol/l. These values were independent of the presence and severity of respiratory distress syndrome and of prenatal maternal steroids.

CONCLUSIONS

The increased 17OHP concentrations found at birth fell to those found in term infants during the first three months of life in infants over 31 weeks of gestation. Postconceptional age is the most important factor determining 17OHP concentration.

Adrenal insufficiency in the term and preterm neonate

The adrenal gland is part of the endocrine system and produces hormones that are essential for survival. The adrenal cortex, the largest part of the adrenal gland, produces three major hormones. Glucocorticoids regulate metabolism of glucose, protein, and fat and allow the body to respond to stress by increasing blood glucose levels and cardiac output. Mineralocorticoids regulate fluid and electrolyte balance and help maintain blood pressure. Androgens are responsible for sexual differentiation in the fetus. Insufficient production of these hormones can occur for many reasons and can have a profound effect on the newborn. It is important for neonatal nurses to be familiar with signs and symptoms and appropriate treatment of adrenal insufficiency. This article explores causes, signs and symptoms, and treatment of adrenal insufficiency in the newborn.

[Neonatal screening of congenital adrenal hyperplasia due to 21-hydroxylase deficiency: Lille experience 1980-1996]

AIM

The results of the neonatal screening of congenital adrenal hyperplasia due to 21-hydroxylase deficiency by 17-hydroxyprogesterone measurement from blood spot on blotting-paper in 408,138 newborns in the French Nord-Pas-de-Calais region from 1980 to 1996 are reported.

METHODS

This measurement successively used a tracer tritium labelled (RIA H3), 125 iodine (RIA I125), then immunofluorometric method (Delfia). From 1992, sampling was systematically performed at the third day of life.

RESULTS

Thirty-three cases were detected and confirmed (20 boys and 13 girls). Diagnosis was made before recalling on a clinical basis in three boys and eight girls. In 22 cases (17 boys and five girls) when diagnosis was not made before recalling, it could have been suspected in three girls because of a sex ambiguity once associated with dehydration and in eight boys because of failure to thrive (six times) or a marked dehydration (twice). Lack of sex ambiguity in two girls characterized non classical form of the illness. These two patients benefited from the early detection of the illness on growth data. Out of 49 subjects who died before recall, three could be suspected of bearing 21-hydroxylase deficiency. One single false negative case was found, which led to decrease cut-off value. On the other hand, false positive cases were frequent (0.37%), mainly in premature newborns (88% of cases).

CONCLUSION

Although decrease of median age for recall at 7 days did not prevent the occurrence of two cases of dehydration, neonatal screening of 21-hydroxylase deficiency appears to be efficient, as far as diagnostic strategy is considered.

Results of screening 1.9 million Texas newborns for 21-hydroxylase-deficient congenital adrenal hyperplasia

OBJECTIVE

To assess results of newborn screening for 21-hydroxylase-deficient congenital adrenal hyperplasia (CAH) in Texas over 6 years of screening 1.9 million infants.

METHODS

In 1989, CAH was incorporated into the ongoing Texas Newborn Screening Program, which requires two screens on each newborn. 17-Hydroxyprogesterone was assayed, without extraction, by radioimmunoassay of blood collected from heel sticks onto filter paper collection cards. Infants with elevated levels of 17-hydroxyprogesterone were referred for evaluation, and those considered to have CAH were studied with respect to disease characteristics. Data were collected by pediatric endocrinologists using standardized forms that included type of CAH, results of laboratory tests, treatment regimen, disease symptoms and signs, and, for girls, degree of genital virilization.

RESULTS

The incidence of classic CAH in Texas is 1:16 008, with a ratio of salt-wasting to simple-virilizing of 2.7:1. A majority of infants detected were undiagnosed until screened, despite signs of salt-wasting or ambiguous genitalia. It was difficult to differentiate salt-wasting from simple-virilizing CAH in infants who were identified before the onset of adrenal insufficiency or electrolyte abnormalities. A substantial number of infants with nonclassic (NC) CAH also were detected. Not all infants were detected on the initial screen; 14% of infants with classic CAH and 87% with NC CAH were detected on the second routine screening test.

CONCLUSIONS

Our findings confirm the benefits of newborn screening for CAH and the importance of a second screening test, and suggest that programs for newborn CAH screening must consider complex issues in diagnosis and treatment. These results also confirm that CAH is a continuum of disorders, rather than a disorder with discrete subtypes. In addition, the difficulties in differentiating CAH subtypes in newborns, and thus deciding appropriate treatment, and the high incidence of NC CAH suggest that standard diagnostic criteria and treatment regimens for CAH may need modification. Where screening exists, physicians will encounter more cases of CAH than in the past.

Improved precision of newborn screening for congenital adrenal hyperplasia using weight-adjusted criteria for 17-hydroxyprogesterone levels

OBJECTIVE

To evaluate the efficacy and efficiency of weight-adjusted threshold levels for 17-hydroxyprogesterone (17-OHP) in screening newborn infants for 21 hydroxylase deficiency-congenital adrenal hyperplasia (21-OH-D-CAH).

DESIGN

Analysis of the number of false-positive reports and diagnoses in infants, of 21-OH-D-CAH with the use of two strategies. Before October 1993, separate criteria for definite abnormal 17-OHP levels were established and implemented for 41,846 infants on the basis of birth weight: either less than 2200 gm (17-OHP level, 90 ng/ml) or 2200 gm or more (40 ng/ml). To reduce the burden of follow-up testing in low birth weight infants, criteria for definite abnormal 17-OHP results were statistically determined for four, rather than two, birth weight divisions: 1299 gm or less (17-OHP level > or = 165 ng/ml), 1300 to 1600 gm (> or = 135 ng/ml), 1700 to 2200 gm (> or = 90 ng/ml), and more than 2200 gm (> or = 40 ng/ml). These criteria were applied to the next 149,684 infants screened, and rates of false-positive test results and of false-positive diagnoses of 21-OH-D-CAH were compared.

RESULTS

Before implementation of four-tiered weight-adjusted 17-OHP criteria, 205 definite abnormal reports yielded four confirmed cases of 21-OH-D-CAH (positive predictive value = 2%; incidence of 21-OH-D-CAH = 1 in 10,461). With the revised criteria, 61 of 149,684 infants had definite abnormal results and 14 cases of 21-OH-D-CAH were confirmed (positive predictive value, 20%; incidence of 21-OH-D-CAH, 1 in 10,692). No undetected severe cases of 21-OH-D-CAH have been subsequently reported.

CONCLUSIONS

Weight-adjusted criteria for 17-OHP levels in screening for 21 -OH-D-CAH markedly reduced the number of false-positive results requiring immediate follow-up testing, particularly among low birth weight infants. Increased specificity afforded by these criteria was not accompanied by diminished sensitivity in detecting severe cases. Long-term follow-up of this screened cohort will determine whether the goals of newborn screening for 21-OH-D-CAH are adequately and efficiently fulfilled by this approach.