Begoña Ezquieta

Analysis of steroid 21-hydroxylase gene mutations in the Spanish population

Steroid 21 -hydroxylase deficiency is the major cause of congenital adrenal hyperplasia. Genotyping for deletions and nine point mutations in the CYP21 gene has been performed in 38 Spanish patients and their relatives by Southern blot analysis and allele-specific oligonucleotide hybridization. Three clinical variants were included in this study, viz., salt-wasting (SW, 21 patients), simple virilizer (SV, two patients), and late-onset (LO, 15 patients) forms. Twenty-three patient genotypes (16 SW, two SV, and five LO) were fully characterized. In both alleles, all but one of these severe forms (SW and SV) presented mutations that abolished or severely affected enzymatic activity. Patients with LO forms showed mutations that moderately impaired enzymatic activity in both alleles, or severe mutations in only one chromosome. Of 46 chromosomes from severe forms, 41 were characterized in this study (89%). The most frequent mutation was an aberrant splicing site (655 A or C to G) in intron 2, in 30% of these chromosomes. Deletions were found in 20%, and large gene conversions in 13% of these alleles. This screening allowed the characterization of 18 out of 30 LO chromosomes, the most frequent mutation being Val281Leu (37%). Severe mutations were found, in heterozygosis, in one third of LO patients.

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.

Prevalencia de enfermedades recesivas frecuentes en población española mediante análisis de ADN en muestras del cribado neonatal

Fundamento y objetivo La fibrosis quistica (FQ) y las formas no clasicas de hiperplasia suprarrenal congenital por deficiencia de 21-hidroxilasa (NC21OHD) son enfermedades autosomicas recesivas frecuentes. En su estudio se utilizan las frecuencias descritas para poblacion caucasica (1:2.500 y 1:1.000, respectivamente). Nos planteamos conocer si estos datos son aplicables a nuestra poblacion. Material y metodo Determinacion de las frecuencias de las mutaciones recurrentes (∼ 50%) de cada entidad, DF508 y Val281Leu, en 300 muestras (600 alelos) consecutivas y anonimas del cribado neonatal. Se realizaron una amplificacion de los genes CFTR y CYP21A2 y un analisis directo de las mutaciones. Resultados Las frecuencias alelicas para DF508 y Val281Leu han sido de 0,005 y 0,038, respectivamente (frecuencia de portadores: un 1,1 y un 7,5%). Considerando que estas mutaciones suponen un 48% (FQ) y un 57% (NC21OHD) de los alelos en pacientes, se estiman unas prevalencias medias de 1:8.028 (FQ) y 1:230 (NC21OHD). Los errores estandar para estos datos son del 0,6 y del 1,5%, respectivamente. Conclusiones En nuestra poblacion, la FQ tiene una menor frecuencia y la NC21OHD es mas prevalente, por lo que no pueden extrapolarse los datos de frecuencia obtenidos en otras poblaciones caucasicas.

Myeloproliferative disorder in Noonan syndrome.

Children with Noonan syndrome (NS) are at increased risk of developing juvenile myelomonocytic leukemia (JMML) or a myeloproliferative disorder associated with NS (MPD/NS) resembling JMML in the first weeks of life; whereas JMML is an aggressive disorder requiring hematopoietic stem cell transplantation, MPD/NS may resolve without treatment and cases with spontaneous remission have also been reported. Two cases of NS with hematologic disorders are described. Diagnosis of the syndrome was confirmed by the identification of earlier reported germline missense mutations in the PTPN11 gene. Splenomegaly in 1 patient and leukocytosis, monocytosis and “in vitro” culture assays consistent with JMML in both were the most salient hematologic features. After a 24-month follow-up, these 2 infants continue to improve and JMML has been ruled out. Splenomegaly persists in 1 patient and monocytosis in both, but without signs of malignancy, thereby suggesting abnormal hematopoiesis or MPD/NS, as described in NS.

Microsatellite markers in the indirect analysis of the steroid 21-hydroxylase gene.

Prenatal diagnosis and treatment of congenital adrenal hyperplasia due to steroid 21‐hydroxylase (21‐OH) deficiency has been proved to be effective. Screening for a panel of nine point mutations, deletions, and gene conversions allows the identification of most of the mutations, although 6–12 per cent of chromosomes remain uncharacterized. In the present study, microsatellite typing in the HLA region was performed in 23 21‐OH deficiency families to determine the usefulness of these markers in the indirect identification of disease alleles. Two Génèthon markers (D6S273 and D6S439) in the HLA complex, class III and II regions in 5′ and 3′, respectively to the CYP21 gene, were typed together with a microsatellite at intron 3 of the TAP1 gene also in 3′. The heterozygosity of these markers provided informativity in all but one family, in which only the father was informative. Direct genotyping of the chromosomes confirmed in each case the correct assignment of the disease alleles in the sibling. The indirect analysis of the 21‐OH gene through D6S273, TAP1, and D6S439 microsatellites provides useful information in the molecular analysis of steroid 21‐OH deficiency.

LEOPARD Syndrome: A Variant of Noonan Syndrome Strongly Associated With Hypertrophic Cardiomyopathy

INTRODUCTION AND OBJECTIVES LEOPARD syndrome is an autosomal dominant condition related to Noonan syndrome, although it occurs less frequently. The aim of this study was to characterize the clinical and molecular features of a large series of LEOPARD syndrome patients. METHODS We collected clinical data from 19 patients in 10 hospitals. Bidirectional sequencing analysis of PTPN11, RAF1, and BRAF focused on exons carrying recurrent mutations. RESULTS After facial dysmorphism, structural heart defects (88%) were the most common feature described. Hypertrophic cardiomyopathy (71%) was diagnosed more often than pulmonary valve stenosis (35%). Multiple lentigines or café au lait spots were found in 84% of the series, and deafness was diagnosed in 3 patients. Mutations in PTPN11 were identified in 16 (84%) patients (10 patients had the recurrent LEOPARD syndrome mutation, p.Thr468Met) (NP_002825.3T468M). Two other patients had a mutation in RAF, and 1 patient had a mutation in BRAF. When compared with other neurocardiofaciocutaneous syndromes, LEOPARD syndrome patients showed a higher prevalence of hypertrophic cardiomyopathy and cutaneous abnormalities, and a lower prevalence of pulmonary valve stenosis and short stature. CONCLUSIONS LEOPARD syndrome patients display distinctive features apart from multiple lentigines, such as a higher prevalence of hypertrophic cardiomyopathy and lower prevalence of short stature. Given its clinical implications, active search for hypertrophic cardiomyopathy is warranted in Noonan syndrome spectrum patients, especially in LEOPARD syndrome patients.

Alteraciones de los genes de la vía RAS-MAPK en 200 pacientes españoles con síndrome de Noonan y otros síndromes neurocardiofaciocutáneos. Genotipo y cardiopatía

INTRODUCTION AND OBJECTIVES Molecular characterization of congenital heart diseases now includes the not infrequent dysmorphic Noonan syndrome. A study of 6 genes of the RAS-MAPK pathway in Spanish patients is presented: the impact of heart disease, clinical expressivity, and diagnostic yield are investigated. METHODS The study included 643 patients (and 182 family members) diagnosed by dysmorphologists, cardiologists, and pediatric endocrinologists from 74 tertiary hospitals. Bidirectional sequencing analysis of PTPN11, SOS1, RAF1, BRAF, KRAS and HRAS focused on exons carrying recurrent mutations accounting for 80% to 95% of previously described mutations. RESULTS Mutations were detected in 230 patients (91 women and 139 men) in 200 (31%) families (172 PTPN11+, 14 SOS1+, 9 RAF1+, 5 BRAF+). There was specific reference to the heart defect suffered in 156 index cases: 103 patients had shown pulmonary stenosis, 12 pulmonary stenosis with hyperthrophic cardiomyopathy, 18 hypertrophic cardiomiopathy, and 14 other cardiopathies; heart disease was absent in 9 index cases. Heart disease had not been documented in 23 of 30 family members with positive genotype and compatible clinical signs. Diagnostic yield was higher (P=.016) for samples from some centers (53%; 14/32) and even from certain professionals (64%; 9/14; P=.019). Characterization rate was 18% in patients for whom clinical data were not available. Genotyping led to a more precise diagnosis in 26 patients. CONCLUSIONS Most patients (94%) with a positive genotype had known congenital heart disease, 79% pulmonary stenosis and 12% hyperthrophic cardiomyopathy. Cardiopathy had not been documented in 76% of family members carrying the mutation. Molecular study is a useful tool in these syndromes but a more rigorous clinical diagnosis should be intended as well.

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

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.

An XX male with an intratubular undifferentiated germ cell neoplasia

OBJECTIVE To report a case of a 46,XX male with an intratubular undifferentiated germ cell neoplasia within an extra-abdominal gonad. DESIGN Case report. SETTING Molecular, cytogenetic, pathologic, and clinical units of three tertiary hospitals. PATIENT(S) A male with ambiguous genitalia at birth and descended testes observed in a pediatric endocrinology setting. INTERVENTION(S) Physical examination, hormonal assays, cytogenetic investigation, molecular analysis, surgical intervention for biopsies and bilateral orchiectomy, and pathologic evaluation. MAIN OUTCOME MEASURE(S) Pathologic evaluation with immunostaining for placental alkaline phosphatase and C-kit. RESULT(S) Conventional chromosome analysis revealed a 46,XXq- karyotype, and fluorescence in situ hybridization experiments with the SRY probe found a signal at the short arm of the deleted X chromosome. Molecular analysis indicated the presence of a portion of the short arm of the Y chromosome including the proto-oncogene TSPY. Pathologic evaluation of the gonads revealed an intratubular undifferentiated germ cell neoplasia. CONCLUSION(S) This is the first case of a 46,XX male with descended testes in whom an intratubular undifferentiated germ cell neoplasia developed. When proposals of management in this subgroup of disorders of sexual differentiation are formulated, the risk of germ cell malignancy must be taken into account.

Síndrome cardiofaciocutáneo, un trastorno relacionado con el síndrome de Noonan: hallazgos clínicos y moleculares en 11 pacientes

OBJECTIVES To describe 11 patients with cardiofaciocutaneous syndrome (CFC) and compare them with 130 patients with other RAS-MAPK syndromes (111 Noonan syndrome patients [NS] and 19 patients with LEOPARD syndrome). PATIENTS AND METHODS Clinical data from patients submitted for genetic analysis were collected. Bidirectional sequencing analysis of PTPN11, SOS1, RAF1, BRAF, and MAP2K1 focused on exons carrying recurrent mutations, and of all KRAS exons were performed. RESULTS Six different mutations in BRAF were identified in 9 patients, as well as 2 MAP2K1 mutations. Short stature, developmental delay, language difficulties and ectodermal anomalies were more frequent in CFC patients when compared with other neuro-cardio-faciocutaneous syndromes (P<.05). In at least 2 cases molecular testing helped reconsider the diagnosis. DISCUSSION CFC patients showed a rather severe phenotype but at least one patient with BRAF mutation showed no developmental delay, which illustrates the variability of the phenotypic spectrum caused by BRAF mutations. Molecular genetic testing is a valuable tool for differential diagnosis of CFC and NS related disorders.