LEOPARD syndrome (PTPN11, T468M) in three boys fulfilling neurofibromatosis type 1 clinical criteria.

Noonan syndrome (NS) and neurofibromatosis type 1 (NF1) are well-defined entities. The association of both disorders is called neurofibromatosis-Noonan syndrome (NFNS), a disorder that has been related to mutations in the NF1 gene. Both NS and NFNS display phenotypic overlapping with LEOPARD syndrome (LS), and differential diagnosis between these two entities often represents a challenge for clinicians. We report on three patients (two brothers and a not-related patient) diagnosed as having NFNS. They fulfilled NF1 diagnostic criteria and had some features of NS. The three of them had hypertophic cardiomyopathy while neurofibromas, Lisch nodules, and unidentified bright objects on MRI were absent. PTPN11 gene assays revealed a T468M mutation, typical of LS. Thorough clinical examinations of the patients revealed multiple lentigines, which were considered to be freckling in the initial evaluation. We conclude that NF1 clinical criteria should be used with caution in patients with features of NS. Patients with hyperpigmented cutaneous spots associated with cardiac anomalies, even if fulfilling the minimal NF1 criteria for diagnosis, should be strongly considered for LS diagnosis.

Carrier detection and prenatal diagnosis of congenital adrenal hyperplasia must identify 'apparently mild' CYP21A2 alleles which associate neonatal salt-wasting disease.

OBJECTIVE: Couples at risk of severe congenital adrenal hyperplasia (CAH) may be offered prenatal treatment or preimplantation diagnosis. However, proper genetic counselling requires the accurate identification of apparently 'mild alleles' in partners of CAH-carriers/patients. METHODS: CYP21A2 gene analyses were performed in 255 patients with severe 21-hydroxylase deficiency (21-OHD), 94 with mild 21-OHD, 752 parental samples, 233 clinically unaffected partners and 253 historic DNA samples. GENSCAN and ClustalX2.0 software were used for in silico analyses, and Epidat 3.1 software for statistical calculations. RESULTS: Twenty-seven partners were carriers of p.Val282Leu (alias p.Val281Leu, allele frequency 11.7%, 7.4-16.1). 'Val282Leu alleles' were detected in 30 patients with salt-wasting (SW) disease, 21 with other pseudogene-derived and rare coding cis severe mutations, and 9 without. These CYP21A2 genes were compared to those of 94 fully characterized patients with mild deficiency carrying p.Val282Leu in compound heterozygosity with a severe allele. A rare intronic variant, c.292+5G>A, was detected in the nine 'severe Val282Leu alleles' and that was not seen in mild p.Val282Leu alleles, in other deficient alleles or in normal chromosomes. The in silico documented effect on splicing and the clinical association (p < 0.0001) confirmed p.Val282Leu; c.292+5G>A as a severe allele. CONCLUSION: As only severe alleles require clinical intervention, CAH-carrier detection of p.Val282Leu should be followed by the analysis of c.292+5G>A.

Formas virilizantes simples de hiperplasia suprarrenal congénita: adaptación y validación prospectiva del cribado molecular de diagnóstico / Simple virilizing forms of congenital adrenal hyperplasia: adaptation and prospective validation of the molecular screening

Fundamento y objetivo: El análisis de mutaciones del gen CYP21A2 es de gran utilidad en el diagnóstico de la hiperplasia suprarrenal congénita (HSC). A diferencia de las formas pierde-sal, solo un 83% de las formas virilizantes simples (VS) se detectan con el cribado básico de mutaciones recurrentes. Las mutaciones raras con una distribución local podrían ser causantes de esta menor eficacia. El objetivo del presente trabajo es identificar nuevas variantes asociadas a formas VS en nuestra población y valorar su impacto en la eficiencia del cribado de diagnóstico.Pacientes y métodos: Fase preliminar: secuenciación de CYP21A2 en 13 pacientes con formas VS y caracterización molecular básica incompleta. Fase retrospectiva: se estudiaron 2.097 muestras de ADN (561 pacientes) para la mutación p.R426H. Fase prospectiva: incorporación de la mutación p.R426H al cribado básico de HSC en 1.041 muestras de ADN (245 pacientes) para la validación del estudio ampliado.Resultados: Se detectó la mutación p.R426H en 5 pacientes de la fase preliminar y 10 más posteriormente. La frecuencia estimada del alelo pp.R426H fue del 0,71% en total y del 7,14% en formas VS. Los haplotipos asociados al alelo mutado sugieren una diseminación preferente del mismo. Los fenotipos observados en los pacientes confirman la afectación moderada-severa de la actividad enzimática codificada. Conclusiones: La frecuencia alélica y su asociación a formas clínicas graves justifican la incorporación de la mutación p.R426H al panel de cribado molecular. La eficiencia diagnóstica mejora especialmente para las formas VS. Dos nuevos casos detectados prospectivamente demuestran la utilidad de esta nueva estrategia (AU)

Background and objective: Congenital Adrenal Hyperplasia (CAH) is not an infrequent genetic disorder for which mutation-based analysis for CYP21A2 gene is a useful tool. Contrarily to salt-wasting forms the basic mutation screening accounts only for 83% of simple virilising (SV) phenotypes. Rare alleles with a local distribution not included in the basic panel may reduce its diagnostic accuracy. Our aim is to explore underlying prevalent mutations among our partially characterised SV forms and to evaluate their potential impact in the mutation screening.Patients and methodsPreliminary study: CYP21A2 gene sequencing in 13 SV patients partially characterised. Retrospective targeted study: 2,097 DNA samples (561 patients) were re-analysed for p.R426H mutation. Prospective targeted study: incorporation of the p.R426H mutation to the initial exploration of CAH in 1,041 DNA samples to validate this extended screening.Results: p.R426H mutation was detected in five patients in the preliminary analysis and in ten more during targeted studies. A frequency for this mutation was 0.71% in the whole group and 7.14% in SV forms. Associated haplotypes were identical thus suggesting a preferential dissemination. The observed phenotypes correlated and confirmed the moderate-to-severe effect on the enzymatic activity.Conclusions: Our data relative to allelic frequency of the p.R426H mutation and its strong association to SV forms justify the incorporation of the p.R426H mutation into the basic screening panel because of the significant improvement in the initial characterization of affected patients, especially among those with SV forms. Two new cases detected remark the usefulness of this novel approach (AU)

[Simple virilizing forms of congenital adrenal hyperplasia: adaptation and prospective validation of the molecular screening]. / Formas virilizantes simples de hiperplasia suprarrenal congénita: adaptación y validación prospectiva del cribado molecular de diagnóstico.

BACKGROUND AND OBJECTIVE: Congenital Adrenal Hyperplasia (CAH) is not an infrequent genetic disorder for which mutation-based analysis for CYP21A2 gene is a useful tool. Contrarily to salt-wasting forms the basic mutation screening accounts only for 83% of simple virilising (SV) phenotypes. Rare alleles with a local distribution not included in the basic panel may reduce its diagnostic accuracy. Our aim is to explore underlying prevalent mutations among our partially characterised SV forms and to evaluate their potential impact in the mutation screening. PATIENTS AND METHODS: Preliminary study: CYP21A2 gene sequencing in 13 SV patients partially characterised. Retrospective targeted study: 2,097 DNA samples (561 patients) were re-analysed for p.R426H mutation. Prospective targeted study: incorporation of the p.R426H mutation to the initial exploration of CAH in 1,041 DNA samples to validate this extended screening. RESULTS: p.R426H mutation was detected in five patients in the preliminary analysis and in ten more during targeted studies. A frequency for this mutation was 0.71% in the whole group and 7.14% in SV forms. Associated haplotypes were identical thus suggesting a preferential dissemination. The observed phenotypes correlated and confirmed the moderate-to-severe effect on the enzymatic activity. CONCLUSIONS: Our data relative to allelic frequency of the p.R426H mutation and its strong association to SV forms justify the incorporation of the p.R426H mutation into the basic screening panel because of the significant improvement in the initial characterization of affected patients, especially among those with SV forms. Two new cases detected remark the usefulness of this novel approach.