Expanding the molecular spectrum of pathogenic SHOC2 variants underlying Mazzanti syndrome.

We previously molecularly and clinically characterized Mazzanti syndrome, a RASopathy related to Noonan syndrome that is mostly caused by a single recurrent missense variant (c.4A > G, p.Ser2Gly) in SHOC2, which encodes a leucine-rich repeat-containing protein facilitating signal flow through the RAS-mitogen-associated protein kinase (MAPK) pathway. We also documented that the pathogenic p.Ser2Gly substitution causes upregulation of MAPK signaling and constitutive targeting of SHOC2 to the plasma membrane due to the introduction of an N-myristoylation recognition motif. The almost invariant occurrence of the pathogenic c.4A > G missense change in SHOC2 is mirrored by a relatively homogeneous clinical phenotype of Mazzanti syndrome. Here, we provide new data on the clinical spectrum and molecular diversity of this disorder and functionally characterize new pathogenic variants. The clinical phenotype of six unrelated individuals carrying novel disease-causing SHOC2 variants is delineated, and public and newly collected clinical data are utilized to profile the disorder. In silico, in vitro and in vivo characterization of the newly identified variants provides evidence that the consequences of these missense changes on SHOC2 functional behavior differ from what had been observed for the canonical p.Ser2Gly change but converge toward an enhanced activation of the RAS-MAPK pathway. Our findings expand the molecular spectrum of pathogenic SHOC2 variants, provide a more accurate picture of the phenotypic expression associated with variants in this gene and definitively establish a gain-of-function behavior as the mechanism of disease.

Two Japanese patients with Noonan syndrome-like disorder with loose anagen hair 2.

Noonan syndrome-like disorder with loose anagen hair (NSLH) is a rare disease characterized by typical features of Noonan syndrome with additional findings of relative or absolute macrocephaly, loose anagen hair, and a higher incidence of intellectual disability. NSLH1 is caused by a heterozygous mutation in the SHOC2 gene on chromosome 10q25, and NLSH2 is caused by a heterozygous mutation in the Protein phosphatase one catalytic subunit beta (PPP1CB) gene on chromosome 2p23. Protein phosphatase1 (PP1), encoded by PPP1CB, forms a complex with SHOC2 and dephosphorylates RAFs, which results in activation of the signaling cascade and contribution to Noonan syndrome pathogenesis. Here, we report two genetically confirmed Japanese patients with NSLH2 having the same de novo mutation in PPP1CB presenting prominent-hyperteloric-appearing eyes and a tall forehead similar to individuals carrying a mutation in PPP1CB, c.146C > G; p.Pro49Arg, which is different from typical facial features of Noonan syndrome. They also showed short stature, absolute macrocephaly, and loose anagen hair like NSLH1: however, growth hormone deficiency often seen in NSLH1 caused by SHOC2 mutation was absent. Although a number of Noonan syndrome and NSLH1 patients have shown blunted or no response to GH therapy, linear growth was promoted by recombinant human growth hormone (rhGH) in one of our patients. Since another NSLH2 patient with good response to rhGH treatment was reported, rhGH therapy may be effective in patients with NSLH2.

Noonan syndrome with loose anagen hair with variants in the PPP1CB gene: First familial case reported.

Rasopathies are a group of phenotypically overlapping conditions that include Noonan, Noonan with multiple lentigines, Noonan with loose anagen hair, Costello, Cardio-facio-cutaneous, and Neurofibromatosis-Noonan syndromes. Noonan syndrome with loose anagen hair (NS-LAH) is clinically characterized by prominent forehead, macrocephaly, growth hormone deficiency, sparse, loose and slow-growing anagen hair, hyperpigmented skin with eczema or ichthyosis, mild psychomotor delays, hypernasal voices, and attention deficit hyperactivity disorder. Variants in SHOC2 are responsible for the majority of the cases. Gripp et al. identified four unrelated individuals with similar phenotype to NS-LAH with pathogenic variants in PPP1CB. In this study, we present one family and one patient with NS-LAH and variants in PPP1CB. The first patient belongs to a family with a likely pathogenic variant, c.545T>A (p.Met182Lys), the first family published so far with a variant in this gene. The second patient harbors a de novo pathogenic variant, c.146C>G (p.Pro49Arg). This study presents two additional patients with this rare syndrome in order to increase the clinical characterization of the syndrome and provide more evidence of the pathogenicity of the c.545T>A (p.Met182Lys) variant in PPP1CB, a gene recently associated with NS-LAH.

A case report of Noonan syndrome-like disorder with loose anagen hair 2 treated with recombinant human growth hormone.

Protein phosphatase 1 catalytic subunit beta (PPP1CB) is a disease-causing gene of Noonan-like syndrome, which acts via the RAS/MAPK pathway. To date, only 17 patients diagnosed with PPP1CB-related Noonan-like syndrome have been reported around the world, with few reports in Asia. Twelve reported patients are of short stature and only one patient was treated with growth hormone (GH); however, follow-up data is lacking. To the best of our knowledge, this is the first reported patient with complete recombinant human growth hormone (rhGH) treatment follow-up data; the patient has a de novo c.146C>G (p.Pro49Arg) mutation in the PPP1CB gene. The hair pattern of the patient (coarse, curly, slow growing, and fragile) combined with Noonan dysmorphic features, developmental delay, and congenital heart disease, are highly consistent with the typical features observed in Noonan syndrome-like disorder with loose anagen hair 2 (NSLH2). rhGH treatment, administered for 3 years and 8 months, promoted the patient's linear growth. Our findings expand the data regarding the treatment of short stature in patients with NSLH2 caused by PPP1CB mutation. Clinical manifestation, growth and development process, and rhGH therapy effect data will aid in future revision of the relevant diagnosis and treatment guidelines.

ADA2 deficiency in a patient with Noonan syndrome-like disorder with loose anagen hair: The co-occurrence of two rare syndromes.

Noonan syndrome-like disorder with loose anagen hair (NS/LAH) is one of the RASopathies, a group of clinically related developmental disorders caused by germline mutations in genes that encode components acting in the RAS/MAPK pathway. Among RASopathies, NS/LAH (OMIM 607721) is an extremely rare, multiple anomaly syndrome characterized by dysmorphic facial features similar to those observed in Noonan syndrome along with some distinctive ectodermal findings including easily pluckable, sparse, thin, and slow-growing hair. ADA2 deficiency (DADA2, OMIM 615688) is a monogenic autoinflammatory disorder caused by homozygous or compound heterozygous mutations in ADA2, with clinical features including recurrent fever, livedo racemosa, hepatosplenomegaly, and strokes as well as immune dysregulation. This is the first report of NS/LAH and ADA2 deficiency in the same individual. We report on a patient presenting with facial features, recurrent infections and ectodermal findings in whom both the clinical and molecular diagnoses of NS/LAH and ADA2 deficiency were established, respectively.

Hematopoietic and neural crest defects in zebrafish shoc2 mutants: a novel vertebrate model for Noonan-like syndrome.

The extracellular signal-related kinase 1 and 2 (ERK1/2) pathway is a highly conserved signaling cascade with numerous essential functions in development. The scaffold protein Shoc2 amplifies the activity of the ERK1/2 pathway and is an essential modulator of a variety of signaling inputs. Germline mutations in Shoc2 are associated with the human developmental disease known as the Noonan-like syndrome with loose anagen hair. Clinical manifestations of this disease include congenital heart defects, developmental delays, distinctive facial abnormalities, reduced growth and cognitive deficits along with hair anomalies. The many molecular details of pathogenesis of the Noonan-like syndrome and related developmental disorders, cumulatively called RASopathies, remain poorly understood. Mouse knockouts for Shoc2 are embryonic lethal, emphasizing the need for additional animal models to study the role of Shoc2 in embryonic development. Here, we characterize a zebrafish shoc2 mutant, and show that Shoc2 is essential for development, and that its loss is detrimental for the development of the neural crest and for hematopoiesis. The zebrafish model of the Noonan-like syndrome described here provides a novel system for the study of structure-function analyses and for genetic screens in a tractable vertebrate system.

Cleft palate and hypopituitarism in a patient with Noonan-like syndrome with loose anagen hair-1.

Noonan syndrome (NS), the most common of the RASopathies, is a developmental disorder caused by heterozygous germline mutations in genes encoding proteins in the RAS-MAPK signaling pathway. Noonan-like syndrome with loose anagen hair (NSLH, including NSLH1, OMIM #607721 and NSLH2, OMIM #617506) is characterized by typical features of NS with additional findings of macrocephaly, loose anagen hair, growth hormone deficiency in some, and a higher incidence of intellectual disability. All NSLH1 reported cases to date have had an SHOC2 c.4A>G, p.Ser2Gly mutation; NSLH2 cases have been reported with a PPP1CB c.146G>C, p.Pro49Arg mutation, or c.166G>C, p.Ala56Pro mutation. True cleft palate does not appear to have been previously reported in individuals with NS or with NSLH. While some patients with NS have had growth hormone deficiency (GHD), other endocrine abnormalities are only rarely documented. We present a female patient with NSLH1 who was born with a posterior cleft palate, micrognathia, and mild hypotonia. Other findings in her childhood and young adulthood years include hearing loss, strabismus, and hypopituitarism with growth hormone, thyroid stimulating hormone (TSH), and gonadotropin deficiencies. The SHOC2 mutation may be responsible for this patient's additional features of cleft palate and hypopituitarism.

SHOC2 subcellular shuttling requires the KEKE motif-rich region and N-terminal leucine-rich repeat domain and impacts on ERK signalling.

SHOC2 is a scaffold protein composed almost entirely by leucine-rich repeats (LRRs) and having an N-terminal region enriched in alternating lysine and glutamate/aspartate residues (KEKE motifs). SHOC2 acts as a positive modulator of the RAS-RAF-MEK-ERK signalling cascade by favouring stable RAF1 interaction with RAS. We previously reported that the p.Ser2Gly substitution in SHOC2 underlies Mazzanti syndrome, a RASopathy clinically overlapping Noonan syndrome, promoting N-myristoylation and constitutive targeting of the mutant to the plasma membrane. We also documented transient nuclear translocation of wild-type SHOC2 upon EGF stimulation, suggesting a more complex function in signal transduction.Here, we characterized the domains controlling SHOC2 shuttling between the nucleus and cytoplasm, and those contributing to SHOC2S2G mistargeting to the plasma membrane, analysed the structural organization of SHOC2's LRR motifs, and determined the impact of SHOC2 mislocalization on ERK signalling. We show that LRRs 1 to 13 constitute a structurally recognizable domain required for SHOC2 import into the nucleus and constitutive targeting of SHOC2S2G to the plasma membrane, while the KEKE motif-rich region is necessary to achieve efficient SHOC2 export from the nucleus. We also document that SHOC2S2G localizes both in raft and non-raft domains, and that it translocates to the non-raft domains following stimulation. Finally, we demonstrate that SHOC2 trapping at different subcellular sites has a diverse impact on ERK signalling strength and dynamics, suggesting a dual counteracting modulatory role of SHOC2 in the control of ERK signalling exerted at different intracellular compartments.

A novel rasopathy caused by recurrent de novo missense mutations in PPP1CB closely resembles Noonan syndrome with loose anagen hair.

Noonan syndrome is a rasopathy caused by mutations in multiple genes encoding components of the RAS/MAPK pathway. Despite its variable phenotype, limited genotype-phenotype correlations exist. Noonan syndrome with loose anagen hair (NS-LAH) is characterized by its distinctive hair anomalies, developmental differences, and structural brain abnormalities and is caused by a single recurrent missense SHOC2 mutation. SHOC2 forms a complex with protein phosphatase 1 (PP1C). Protein phosphatases counterbalance kinases and control activation of signaling proteins, such as the mitogen-activated protein kinases of the RAS/MAPK pathway. Here we report four patients with de novo missense mutations in protein phosphatase one catalytic subunit beta (PPP1CB), sharing a recognizable phenotype. Three individuals had the recurrent PPP1CB c.146G>C, p.Pro49Arg mutation, the fourth had a c.166G>C, p.Ala56Pro change. All had relative or absolute macrocephaly, low-set and posteriorly angulated ears, and developmental delay. Slow growing and/or sparse hair and/or an unruly hair texture was present in all. Three individuals had feeding difficulties requiring feeding tubes. One of two males had cryptorchidism, another had pectus excavatum. Short stature was present in three. A female with the recurrent mutation had a Dandy-Walker malformation and optic nerve hypoplasia. Mild ventriculomegaly occurred in all, cerebellar tonsillar ectopia was seen in two and progressed to Chiari 1 malformation in one individual. Based on the combination of phenotypic findings and PPP1CB's effect on RAF dephosphorylation within the RAS/MAPK pathway, this novel condition can be considered a rasopathy, most similar to NS-LAH. Collectively, these mutations meet the standardized criteria for pathogenicity. © 2016 Wiley Periodicals, Inc.

N(1)-methylspermidine, a stable spermidine analog, prolongs anagen and regulates epithelial stem cell functions in human hair follicles.

Spermidine (Spd), the prototypic polyamine, has been shown to be essential for hair follicle (HF) growth. However, Spd can be readily converted into other polyamines, and is physiologically unstable. Therefore, to assess its individual functions on HFs, we used the metabolically stable Spd analog N(1)-methylspermidine (N(1)-MeSpd). N(1)-MeSpd was confirmed to be a metabolically stable compound, with a half life of 90 h. 0.5 µM N(1)-MeSpd strongly prolonged anagen and decreased cell apoptosis in HFs in culture after 6 days, accompanied by specific stimulation of the expression of the epithelial stem cell-associated keratin, K15. N(1)-MeSpd also reduced lactate dehydrogenase activity in the culture supernatant, a parameter of cell death and cell lysis. N(1)-MeSpd diminished intracellular reactive oxygen species production in cultured keratinocytes, and reduced tumor necrosis factor-α, interleukin (IL)-1ß and IL-6 gene and protein expression after lipopolysaccharide stimulation. This suggests that some effects of N(1)-MeSpd may be mediated by anti-oxidative and anti-inflammatory effects. These additional properties of N(1)-MeSpd could be clinically important for the treatment of inflammatory alopecias and inflammatory scalp diseases.

Improved growth velocity of a patient with Noonan-like syndrome with loose anagen hair (NS/LAH) without growth hormone deficiency by low-dose growth hormone therapy.

Noonan-like syndrome with loose anagen hair (NS/LAH; OMIM 607721) is caused by a heterozygous c.4A>G mutation in SHOC2. Most cases exhibit both growth hormone deficiency (GHD) and growth hormone insensitivity (GHI) and thus require a high dose of growth hormone (GH) therapy (e.g., 35-40 µg/kg/day). We report on a genetically diagnosed NS/LAH patient manifesting severe short stature (-3.85 SDs) with low serum level of IGF1, 30 ng/ml. The peak levels of GH stimulation tests were within the normal range, and GHI was not observed in the IGF1 generation test. However, with low-dose GH therapy (25 µg/kg/day) for two years, IGF1 level and height were remarkably improved (IGF1: 117 ng/ml, height SDs: -2.20 SDs). Further, catch-up of motor development and improvement of the proportion of extending limbs to trunk were observed (the Developmental Quotient score increased from 68 to 98 points, and the relative sitting height ratio decreased from 0.62 to 0.57). Our results suggest that endocrinological causes for short stature are variable in NS/LAH and that GH therapy should be considered as a possible treatment for delayed development in NS/LAH.

Moyamoya disease in two patients with Noonan-like syndrome with loose anagen hair.

Moyamoya disease is a unique chronic cerebrovascular condition caused by progressive stenosis of the arteries around the circle of Willis with prominent arterial collateral circulation. Noonan-like syndrome with loose anagen hair (NSLH) is characterized by short stature, characteristic facial phenotype, darkly pigmented and hairless skin, mild psychomotor delay with attention deficit disorder, and easily pluckable, sparse, thin, slow growing hair. Mutations in SHOC2 have been reported to underlie NSLH. In this paper, we describe two individuals with NSLH who also have moyamoya disease and in whom heterozygous germline mutation in SHOC2 was found.

Moyamoya syndrome in a patient with Noonan-like syndrome with loose anagen hair.

BACKGROUND: Noonan-like syndrome with loose anagen hair is one of the RASopathies characterized by Noonan syndrome-like features with unique ectodermal abnormalities. This syndrome is caused by mutations in the SHOC2 gene. We encountered a patient with moyamoya syndrome associated with Noonan-like syndrome with loose anagen hair presenting with transient ischemic attacks. PATIENT DESCRIPTION: A 6-year-old girl was diagnosed with Noonan-like syndrome with loose anagen hair because of profound short stature and ectodermal anomalies such as sparse and easily pluckable hair. A heterozygous mutation of c.4A>G (p.S2G) in the SHOC2 gene was identified, and recombinant human growth hormone therapy was initiated at 8 years of age. At age 10, she manifested recurrent left hemiplegia. Moreover, cerebrovascular imaging revealed occlusion or narrowing of both internal carotid arteries and both middle cerebral arteries with distal moyamoya-like vessels. She is treated with aspirin and calcium channel blocker. CONCLUSIONS: We describe the first case of Noonan-like syndrome with loose anagen hair associated with moyamoya syndrome, although it has been reported to be associated with a few cases of other RASopathies, including Noonan, cardiofaciocutaneous, and Costello syndromes. This report emphasizes the associations between cerebrovascular anomalies and Noonan-like syndrome with loose anagen hair.

Phenotypic variability associated with the invariant SHOC2 c.4A>G (p.Ser2Gly) missense mutation.

Noonan-like syndrome with loose anagen hair (NS/LAH; OMIM 607721) is a developmental disorder clinically related to Noonan syndrome (NS) and characterized by facial dysmorphisms, postnatal growth retardation, cardiac anomalies (in particular dysplasia of the mitral valve and septal defects), variable neurocognitive impairment, and florid ectodermal features. A distinctive trait of NS/LAH is its association with easily pluckable, slow growing, sparse, and thin hair. This rare condition is due to the invariant c.4A > G missense (p.Ser2Gly) change in SHOC2, which encodes a regulatory protein that participate in RAS signaling. Here we report two patients with molecularly confirmed NS/LAH, with extremely different phenotypic expression, in particular concerning the severity of the cardiac phenotype and neurocognitive profile. While the first available clinical records outlined a relatively homogeneous phenotype in NS/LAH, the present data emphasize that the phenotype spectrum associated with this invariant mutation is wider than previously recognized.

Hydrops fetalis in a preterm newborn heterozygous for the c.4A>G SHOC2 mutation.

Fetal hydrops is a condition resulting from interstitial fluid accumulation in fetal compartments secondary to increased capillary permeability and characterized by high rates of perinatal mortality and morbidity. Clinical features include skin edema, hydrothorax, pericardial effusion, ascites with or without polyhydramnios, and placental edema. While it may occur as associated feature in multiple disorders, it has been documented to recur in Noonan syndrome, the most common disorder among RASopathies, but also in cardiofaciocutaneous and Costello syndromes. Here, we report on the occurrence of severe hydrops in a newborn heterozygous for the invariant c.4A>G missense change in SHOC2 which underlies Noonan-like syndrome with loose anagen hair, documenting that it represents a clinically relevant complication in this condition, shared by RASopathies.

Coarctation of the aorta in Noonan-like syndrome with loose anagen hair.

Noonan-like syndrome with loose anagen hair (NS/LAH; OMIM 607721) due to a missense mutation c.4A>G in SHOC2 predicting p.Ser2Gly has been described recently. This condition is characterized by facial features similar to Noonan syndrome, reduced growth, cardiac defects, and typical abnormal hair. We report on a patient with molecularly confirmed NS/LAH with coarctation of the aorta. The girl was precipitously born at 37 weeks of gestation at home and required a 3-min resuscitation. Increased nuchal translucency and aortic coarctation with a small ventricular septal defect were described prenatally, hypertrophic cardiomyopathy was detected postnatally. The patient presented with facial dysmorphism typical of NS with redundant skin over the nape and on the back. Short stature, relative macrocephaly, failure-to-thrive together with dystrophic appearance, developmental delay mainly in motor milestones and very thin, sparse, slow-growing hair occurred a few weeks after birth. Endocrine evaluation revealed low IGF-1 levels and borderline growth hormone deficiency. Growth hormone therapy started at 16 months had a partial effect and prevented further growth deterioration. Coarctation of the aorta is not a typical heart defect among individuals with NS/LAH, therefore our observation extends the phenotypic spectrum of this disorder.

GH Therapy and first final height data in Noonan-like syndrome with loose anagen hair (Mazzanti syndrome).

Noonan-like syndrome with loose anagen hair (NS/LAH or Mazzanti Syndrome) is caused by a single missense mutation in SHOC2 promoting tN-myristoylation of the encoded protein. Cardinal features include facial features resembling NS, short stature often associated with proven growth hormone deficiency (GHD), typical ectodermal anomalies, and distinctive behavior. Overall, the clinical features are more severe than those generally observed in NS, even though the phenotype improves with age. We report on growth and pubertal trend in seven patients heterozygous for a mutated SHOC2 allele, treated with long-term GH-therapy, and final height (FH) in three of them. They were approximately -3 SDS below the Italian general population standards, they had very low IGF1 levels at baseline and GHD at pharmacological tests. All patients were treated with GH (0.035 mg/kg/day) for a mean period of 8.49 ± 5.72 years. After the 1st year of GH-therapy, IGF1 level and height velocity had increased. Three of 7 patients reached the FH (-2.34 ± 0.12 SDS) at 18.25 ± 0.73 years, after GH administration for 12.39 ± 2.12 years. Pubertal development was variable, showing a prolonged and delayed puberty or rapid pubertal progression that could impair the FH. Overall, our data in this small cohort suggest that NS/LAH patients benefit from long-term GH-therapy, although they do not show the characteristic catch-up growth of isolated GHD. While the observed growth and pubertal behavior is consistent with a dysfunction of the hypothalamic-pituitary-gonadal axis, the functional link between SHOC2 and the GH/IGF signaling pathways remains to be clarified.

Loose anagen hair syndrome in black-haired Indian children.

Loose anagen hair syndrome (LAHS) is an uncommonly reported autosomal dominant hair disorder with incomplete penetrance that primarily affects children but is occasionally seen in adults. LAHS is characterized by the ability to easily and painlessly extract unsheathed anagen hairs from the scalp with gentle traction. The hair is sparse and does not grow long. Usually the hairs are not fragile and do not have areas of breakage. Initially it was considered a rare, sporadic condition found predominantly in young white girls with blonde hair. Because autosomal dominant inheritance has been reported, it was suspected that the condition might be equally common in boys but was probably underdiagnosed.

Clinical Heterogeneity in two patients with Noonan-like Syndrome associated with the same SHOC2 mutation.

Noonan-like syndrome with loose anagen hair (NS/LAH; OMIM #607721) has been recently related to the invariant c.4A > G missense change in SHOC2. It is characterized by features reminiscent of Noonan syndrome. Ectodermal involvement, short stature associated to growth hormone (GH) deficiency (GHD), and cognitive deficits are common features. We compare in two patients with molecularly confirmed NS/LAH diagnosis, the clinical phenotype and pathogenetic mechanism underlying short stature. In particular, while both the patients exhibited a severe short stature, GH/IGFI axis functional evaluation revealed a different pathogenetic alteration, suggesting in one patient an upstream alteration (typical GHD) and in the other one a peripheral GH insensitivity.