Retinitis pigmentosa in a young man with Noonan syndrome: further evidence that Noonan syndrome (NS) and the cardio-facio-cutaneous syndrome (CFC) are variable manifestations of the same entity?

The Helena syndromes

The author gives a personal account on how he was introduced to the field of clinical genetics as a student of John Opitz in Helena, MT. That process was facilitated by the study of several malformation syndromes. Particularly instructive were the approaches to the cardio-facio-cutaneous, the Perlman, and the FG syndrome. These three conditions are briefly revisited with a critical perspective, made possible by the elapse of 20 years, since the time when the author became acquainted with them.

The cardiofaciocutaneous syndrome

The cardiofaciocutaneous (CFC) syndrome is a condition of sporadic occurrence, with patients showing multiple congenital anomalies and mental retardation. It is characterised by failure to thrive, relative macrocephaly, a distinctive face with prominent forehead, bitemporal constriction, absence of eyebrows, hypertelorism, downward-slanting palpebral fissures often with epicanthic folds, depressed nasal root and a bulbous tip of the nose. The cutaneous involvement consists of dry, hyperkeratotic, scaly skin, sparse and curly hair, and cavernous haemangiomata. Most patients have a congenital heart defect, most commonly pulmonic stenosis and hypertrophic cardiomyopathy. The developmental delay usually is moderate to severe. The syndrome is caused by gain-of-function mutations in four different genes BRAF, KRAS, mitogen-activated protein/extracellular signal-regulated kinase MEK1 and MEK2, all belonging to the same RAS-extracellular signal-regulated kinase (ERK) pathway that regulates cell differentiation, proliferation and apoptosis. The CFC syndrome is a member of a family of syndromes that includes the Noonan and Costello syndromes, presenting with phenotypic similarities. Noonan syndrome is caused by mutations in the protein tyrosine phosphatase SHP-2 gene (PTPN11), with a few people having a mutation in KRAS. Costello syndrome is caused by mutations in HRAS. The protein products of these genes also belong to the RAS-ERK pathway. Thus, the clinical overlap of these three conditions, which often poses a problem of differential diagnosis, is explained by their pathogenetic relatedness.

First small supernumerary ring chromosome carrying 10q euchromatin in a patient with mild phenotype characterized by molecular cytogenetic techniques and review of the literature

We report the identification and characterization of the first supernumerary ring chromosome 10 containing a considerable proportion of 10q euchromatin by microdissection and reverse painting in a female patient presenting with short stature. Fluorescence in situ hybridization studies showed that the marker chromosome originates from chromosome 10 and includes the euchromatic bands p11.2 and q11.2. The supernumerary marker chromosome 10 was found in 14% of the peripheral blood lymphocytes analyzed. This constitutional mosaic could be confirmed in oral mucosa cells as a second cell system (16%) by interphase FISH using an alphoid centromeric probe for chromosome 10. Parental karyotypes were normal, uniparental disomy for the normal chromosomes 10 could be excluded by microsatellite analysis. The karyotype of the patient detected in peripheral blood cells can be described as mos 47,XX,+mar.rev ish r(10)(p11.2q11.2)(wcp10+,cep10+)/46,XX.

Cutaneous manifestations in the cardiofaciocutaneous syndrome, a variant of the classical Noonan syndrome. Report of a case and review of the literature

We report one patient with cardiofaciocutaneous (CFC) syndrome. He presented with clinical findings characteristic of this condition such as: cutaneous abnormalities, including ichthyosis, widespread keratosis pilaris, a peculiar craniofacial appearance with sparse, curly hair and low-set posteriorly rotated ears; congenital heart defects; and mild mental and motor retardation. We submit a comprehensive review of previously published articles regarding the dermatological findings in CFC syndrome (recently shown to be a variant of Noonan syndrome) emphasizing diagnostic criteria and its differentiation from the Costello syndrome.

PTPN11 mutations are not responsible for the Cardiofaciocutaneous (CFC) syndrome

Cardiofaciocutaneous (CFC) syndrome is a multiple congenital anomalies/mental retardation syndrome characterized by congenital heart defects, characteristic facial appearance, short stature, ectodermal abnormalities and mental retardation. It was described in 1986, and to date is of unknown genetic etiology. All reported cases are sporadic, born to non-consanguineous parents and have apparently normal chromosomes. Noonan and Costello syndromes remain its main differential diagnosis. The recent finding of PTPN11 missense mutations in 45-50% of the Noonan patients studied with penetrance of almost 100% and the fact that in animals mutations of this gene cause defects of semilunar valvulogenesis, made PTPN11 mutation screening in CFC patients a matter of interest. We sequenced the entire coding region of the PTPN11 gene in ten well-characterised CFC patients and found no base changes. We also studied PTPN11 cDNA in our patients and demonstrated that there are no interstitial deletions either. The genetic cause of CFC syndrome remains unknown, and PTPN11 can be reasonably excluded as a candidate gene for the CFC syndrome, which we regard as molecular evidence that CFC and Noonan syndromes are distinct genetic entities.

Cardio-facio-cutaneous syndrome and moyamoya syndrome

We reported a patient with cardio-facio-cutaneous (CFC) syndrome associated with moyamoya syndrome. The patient was referred at 6 years 5 months with left hemiplegia and right-sided eye deviation. He had an apparently short stature, macrocephaly, left ptosis and atopic skin, and was odd looking. He exhibited an incomplete right bundle branch block on electrocardiogram and an atrial septal defect on ultrasound cardiography. He was diagnosed as having CFC syndrome. Head magnetic resonance imaging showed a flow void in the bilateral basal ganglia, but did not show any ischemic changes. Magnetic resonance angiography showed bilateral stenosis with an internal carotid artery at the Willis artery ring level and bilateral moyamoya. Contrast angiography demonstrated occlusion of both middle cerebral arteries. Cerebrovascular anomalies have not previously been reported in CFC syndrome. This is the first case of CFC syndrome associated with moyamoya syndrome.

Apaf1 (CED-4 homolog) regulates programmed cell death in mammalian development

The cytosolic protein APAF1, human homolog of C. elegans CED-4, participates in the CASPASE 9 (CASP9)-dependent activation of CASP3 in the general apoptotic pathway. We have generated by gene trap a null allele of the murine Apaf1. Homozygous mutants die at embryonic day 16.5. Their phenotype includes severe craniofacial malformations, brain overgrowth, persistence of the interdigital webs, and dramatic alterations of the lens and retina. Homozygous embryonic fibroblasts exhibit reduced response to various apoptotic stimuli. In situ immunodetection shows that the absence of Apaf1 protein prevents the activation of Casp3 in vivo. In agreement with the reported function of CED-4 in C. elegans, this phenotype can be correlated with a defect of apoptosis. Our findings suggest that Apaf1 is essential for Casp3 activation in embryonic brain and is a key regulator of developmental programmed cell death in mammals.