Clinical variability in a Noonan syndrome family with a new PTPN11 gene mutation.
ABSTRACT Noonan syndrome (NS) is an autosomal dominant disorder comprising short stature, facial dysmorphism, short and/or webbed neck, heart defects, and cryptorchidism in males. The gene responsible for the disorder (PTPN11) was recently identified, and explains 30-50% of the cases clinically diagnosed as NS. Cardiofaciocutaneous (CFC) syndrome, a similar but distinct entity, is characterized by relative macrocephaly, characteristic facial appearance, ectodermal abnormalities (sparse and friable hair, sparse eyebrows, hyperkeratotic skin), congenital heart defects, and growth and mental retardation. We describe on a young woman who presents clinical features of NS (short stature, triangular facies, with downslanting palpebral fissures and apparent hypertelorism, webbed neck, pulmonary stenosis, bleeding diathesis, prominent corneal nerves), but with a more prominent ectodermal involvement (sparse and very coarse hair, sparse eyebrows and eyelashes) and developmental delay/mental retardation, which are characteristic of CFC patients. Sequencing of the PTPN11 gene showed a T411M substitution, not previously described in patients with NS. The same mutation was found in her mother and older sister, not initially considered to be affected by NS, but with very subtle clinical findings compatible with this diagnosis. Molecular dynamic studies indicate that this new mutation, similar to other previously described mutations, favors a more active protein conformation. However, the main disruptive effect is not directly in the catalytic domain, suggesting that the location of this mutation could make the protein more susceptible to gene-gene or gene-environment interactions. Atypical cases of NS should be screened for mutations in the PTPN11 gene and in the case of a positive result, first-degree relatives should also be tested for the specific mutation.
Article: Syndromes neuro-cardio-facio-cutanésAnnales de Dermatologie et de Vénéréologie 06/2011; 138(6):483-493. DOI:10.1016/j.annder.2011.02.029 · 0.67 Impact Factor
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ABSTRACT: Detailed longitudinal evaluation of corneal and other ophthalmological features of patients with lipoid proteinosis (LP). Ophthalmological examinations, chart review, ultrasound biomicroscopy, corneal confocal microscopic examinations with Nidek confoScan 4 and direct sequencing of the extracellular matrix protein 1 gene in individuals from three consanguineous Saudi families with LP. Seven individuals affected with LP (four female and three male subjects) were evaluated together with nine unaffected parents and siblings. All affected individuals had homozygous mutations in extracellular matrix protein 1. Four patients were examined frequently (every 6 months) beginning in infancy and early childhood. Globe and vision were normal in all individuals, and moniliform blepharosis always appeared after the age of 4 years. Prominent corneal nerves were detected in all patients regardless of age and were more apparent in patients with more severe genetic mutations. Conversely, the severity of moniliform blepharosis seemed age-dependent rather than genotype-related. Prominent corneal nerves can be helpful in the early diagnosis of LP and should be added to the list of LP ophthalmological diagnostic features.The British journal of ophthalmology 05/2012; 96(7):935-40. DOI:10.1136/bjophthalmol-2012-301617 · 2.81 Impact Factor
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ABSTRACT: Costello syndrome is caused by HRAS germline mutations affecting Gly(12) or Gly(13) in >90% of cases and these are associated with a relatively homogeneous phenotype. Rarer mutations in other HRAS codons were reported in patients with an attenuated or mild phenotype. Disease-associated HRAS missense mutations result in constitutive HRAS activation and increased RAF-MEK-ERK and PI3K-AKT signal flow. Here we report on a novel heterozygous HRAS germline alteration, c.266C>G (p.S89C), in a girl presenting with severe fetal hydrops and pleural effusion, followed by a more benign postnatal course. A sibling with the same mutation and fetal polyhydramnios showed a Dandy-Walker malformation; his postnatal course was complicated by severe feeding difficulties. Their apparently asymptomatic father is heterozygous for the c.266C>G change. By functional analyses we identified reduced levels of active HRAS(S89C) and diminished MEK, ERK and AKT phosphorylation in cells overexpressing HRAS(S89C) , which represent novel consequences of disease-associated HRAS mutations. Given our patients' difficult neonatal course and presence of this change in their asymptomatic father, we hypothesize that its harmful consequences may be time limited, with the late fetal stage being most sensitive. Alternatively, the phenotype may develop only in the presence of an additional as-yet-unknown genetic modifier. While the pathogenicity of the HRAS c.266C>G change remains unproven, our data may illustrate wide functional and phenotypic variability of germline HRAS mutations.American Journal of Medical Genetics Part A 09/2012; 158A(9):2106-18. DOI:10.1002/ajmg.a.35449 · 2.05 Impact Factor