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

Mid-aortic Syndrome in a Pediatric Cohort

Mid-aortic syndrome (MAS) is an uncommon condition characterized by severe narrowing of the abdominal aorta, usually involving visceral and renal arteries. Most patients are asymptomatic and typically present with incidental hypertension which might evolve into end-organ damage if untreated. Our aim was to review 8 new pediatric MAS cases. A retrospective observational study of all pediatric patients with MAS diagnosis (April 1992-November 2021) was conducted. Patients underwent systematic evaluation (medical and family history; 12-lead electrocardiogram; echocardiogram; angiography and/or computed tomography or magnetic resonance angiography). 8 pediatric patients with MAS were included. Median age at diagnosis was 2.6 [0.2-4.7] years; median follow-up time was 8.6 [6.6-10.0] years. 6/8 patients presented with incidental hypertension, 1/8 with heart murmur, and 1/8 with heart failure symptoms. All patients were on antihypertensive treatment. 1/8 patients underwent surgery and 7/8 an endovascular treatment. At the end of the study period, among the 6 patients that underwent a successful endovascular procedure, 2 achieved good blood pressure (BP) control, 2 acceptable BP control, 1 stage 1 hypertension and, another, stage 2 hypertension. There was 1 death during follow-up. BP monitoring in pediatric patients is crucial for early recognition of MAS. Treatment should be based on the individual clinical characteristics of patients with careful planning of surgical revascularisation, if possible, after adult growth is completed. Our study demonstrates that endovascular treatment might be a good alternative to surgery. Nevertheless, further trials with larger sample size and longer-term follow-up are required to determine the best treatment approach.

Lymphatic Abnormalities in Noonan Syndrome Spectrum Disorders: A Systematic Review

Noonan syndrome spectrum disorders are a group of phenotypically related conditions, resembling Noonan syndrome, caused by germline pathogenic variants in genes within the Ras/mitogen-activated protein kinase (Ras/MAPK) signalling pathway. Lymphatic dysplasia with a clinical lymphatic abnormality is one of the major features. We performed a systematic review to get more insight in (1) the prevalence of clinically lymphatic abnormalities in patients with a genetically proven Noonan syndrome spectrum disorder, (2) if a genotype-lymphatic phenotype relation can be found and describe the clinical presentation and course of the lymphatic abnormality. Most studies report patients with Noonan syndrome. Prenatally, the prevalence of increased nuchal translucency differs from 7% in patients with pathogenic PTPN11 variants to 38% in patients with pathogenic RIT1 variants, and the prevalence of pleural effusions differed from 7% in patients with pathogenic SOS1 to 29% in patients with pathogenic RIT1 variants. Postnatally, the prevalence of lymphedema differs from 16% in patients with pathogenic PTPN11 variants to 44% in patients with pathogenic SOS1 variants, and the prevalence of acquired chylothorax is 4% in patients with pathogenic RIT1 variants. Lymphatic abnormalities do occur in patients with cardiofaciocutaneous syndrome and Costello syndrome. In conclusion, Noonan syndrome spectrum disorders, Noonan syndrome in particular, are associated with lymphatic abnormalities. Combining the available published literature about genetically proven Noonan syndrome spectrum disorders, it appears likely that the lifetime prevalence of these abnormalities in Noonan syndrome is higher than the 20% that were generally accepted so far. This is increasingly important, because the activation of the RAS/MAPK pathway can be inhibited by RAS/MAPK inhibitors, and clinically severe lymphatic abnormalities may improve.

Hypertrophic Cardiomyopathy in RASopathies: Diagnosis, Clinical Characteristics, Prognostic Implications, and Management

RASopathies are multisystemic disorders caused by germline mutations in genes linked to the RAS/mitogen-activated protein kinase pathway. Diagnosis of RASopathy can be triggered by clinical clues ("red flags") which may direct the clinician toward a specific gene test. Compared with sarcomeric hypertrophic cardiomyopathy, hypertrophic cardiomyopathy in RASopathies (R-HCM) is associated with higher prevalence of congestive heart failure and shows increased prevalence and severity of left ventricular outflow tract obstruction. Biventricular involvement and the association with congenital heart disease, mainly pulmonary stenosis, have been commonly described in R-HCM. The aim of this review is to assess the prevalence and unique features of R-HCM and to define the available therapeutic options.

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.

Clinical and functional characterization of a novel RASopathy-causing SHOC2 mutation associated with prenatal-onset hypertrophic cardiomyopathy

SHOC2 is a scaffold protein mediating RAS-promoted activation of mitogen-activated protein kinase (MAPK) signaling in response to extracellular stimuli. A recurrent activating mutation in SHOC2 (p.Ser2Gly) causes Mazzanti syndrome, a RASopathy characterized by features resembling Noonan syndrome and distinctive ectodermal abnormalities. A second mutation (p.Met173Ile) supposed to cause loss-of-function was more recently identified in two individuals with milder phenotypes. Here, we report on the third RASopathy-causing SHOC2 mutation (c.807_808delinsTT, p.Gln269_His270delinsHisTyr), which was found associated with prenatal-onset hypertrophic cardiomyopathy. Structural analyses indicated a possible impact of the mutation on the relative orientation of the two SHOC2's leucine-rich repeat domains. Functional studies provided evidence of its activating role, revealing enhanced binding of the mutant protein to MRAS and PPP1CB, and increased signaling through the MAPK cascade. Differing from SHOC2 ^S2G , SHOC2 ^{Q269_H270delinsHY} is not constitutively targeted to the plasma membrane. These data document that diverse mechanisms in SHOC2 functional dysregulation converge toward MAPK signaling upregulation.

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.

Loose Anagen Syndrome: A Retrospective Chart Review of 37 Cases

BACKGROUND/OBJECTIVES

Loose anagen syndrome (LAS) is a disorder of abnormal anchorage of the hair to the scalp. Its symptoms include an inability to grow hair long and hair that is easily pulled out.

METHODS

We conducted a retrospective chart review of patients with LAS over the last 10 years at the Children's Hospital of Philadelphia and found 37 cases.

RESULTS

LAS was more common in females and was found in all hair colors and skin types.

CONCLUSION

Diagnosis of LAS should be made based on history, microscopic findings, and hair bulb and shaft features.

Noonan syndrome-like disorder with loose anagen hair: a second case with neuroblastoma

Noonan-like syndrome with loose anagen hair (NSLH), also known as Mazzanti syndrome, is a RASopathy characterized by craniofacial features resembling Noonan syndrome, cardiac defects, cognitive deficits and behavioral issues, reduced growth generally associated with GH deficit, darkly pigmented skin, and an unique combination of ectodermal anomalies. Virtually all cases of NSLH are caused by an invariant and functionally unique mutation in SHOC2 (c.4A>G, p.Ser2Gly). Here, we report on a child with molecularly confirmed NSLH who developed a neuroblastoma, first suspected at the age 3 months by abdominal ultrasound examination. Based on this finding, scanning of the SHOC2 coding sequence encompassing the c.4A>G change was performed on selected pediatric cohorts of malignancies documented to occur in RASopathies (i.e., neuroblastoma, brain tumors, rhabdomyosarcoma, acute lymphoblastic, and myeloid leukemia), but failed to identify a functionally relevant cancer-associated variant. While these results do not support a major role of somatic SHOC2 mutations in these pediatric cancers, this second instance of neuroblastoma in NSLAH suggests a possible predisposition to this malignancy in subjects heterozygous for the c.4A>G SHOC2 mutation.

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.