Трансплантация сердца у ребенка с синдромом Нунан

Резюме

Синдромы, вызванные мутациями в генах, кодирующих компоненты сигнального пути RAS/MAPK (RASопатии), клинически и генетически гетерогенны.
Наиболее частые проявления этих синдромов - врожденные заболевания сердца и сосудов, кардиомиопатии, скелетные аномалии, множественные лентиго, предрасположенность к новообразованиям, задержка физического и умственного развития разной степени. Известно, что мутации более чем в 10 генах приводят к развитию RASопатий, и этот список продолжает пополняться. Развернутый клинический фенотип RASопатий очевиден, однако на ранних стадиях заболевания постановка диагноза может вызывать определенные трудности.

Цель - в настоящей работе представлен случай успешной трансплантации сердца ребенку с синдромом Нунан в возрасте 3 года 8 мес.

Материал и методы. Клиническое, биохимическое и инструментальное обследование включало разовые электрокардиограммы покоя и 24-часовое суточное холтеровское мониторирование, допплерографию, ультразвуковое исследование сердца, определение активности ферментов. Генетическое исследование включало классическое цитогенетическое обследование (кариотип), секвенирование по Сенгеру кодирующих и прилегающих интронных областей генов LMNA, PTPN11 и RAF1.

Клинический случай. Девочка впервые поступила в детское кардиологическое отделение в возрасте 4,5 мес с симптомами сердечной недостаточности. Была диагностирована симметричная обструктивная гипертрофическая кардиомиопатия. Учитывая многочисленные особенности фенотипа, заподозрили синдромную природу заболевания. Был диагностирован синдром Нунан, вызванный мутацией p. Gln510Glu в гене PTPN11. В связи с быстрым прогрессированием гипертрофии миокарда и сердечной недостаточности ребенку выполнена трансплантация сердца. В течение 1 года после трансплантации состояние девочки стабильное, жалоб на состояние здоровья нет.

Заключение. У пациентов с RASопатиями ингибирование мутантного пути RAS/MAPK может рассматриваться как возможный подход к терапии. Однако сейчас для пациентов детского возраста с быстропрогрессирующей гипертрофией миокарда трансплантация сердца является единственным вариантом лечения с доказанной эффективностью. 

Ключевые слова:гипертрофическая кардиомиопатия, синдром Нунан, RAS-каскад, трансплантация сердца, PTPN11, ДНК-диагностика

Клин. и эксперимент. хир. Журн. им. акад. Б.В. Петровского. 2017. № 3. С. 65-70.

Статья поступила в редакцию: 21.06.2017. Принята в печать: 07.07.2017. 

RAS proteins bound to certain enzymes, including RAS mitogen-activated protein kinase (MAPK), provide regulation of signal transduction, control cellular proliferation, differentiation and survival. RASopathies are group of syndromes caused by mutations in various genes of the RAS/MAPK pathway. RASopathies-associated gene panel covers five major genes, including more than 70% mutations: PTPN11, BRAF, KRAS, RAF1, and SOS1 but the list of genetic forms was significantly expanded [1]. RASopathies are characterized by a combination of cardiac and skin changes, dysplastic phenotype, difficulty in learning, some patients develop lymphoproliferative disorders. This group includes Noonan syndrome, LEOPARD, Costello syndrome, cardio faciocutaneous syndrome, Legius syndrome and a wide range of overlapping phenotypes [1]. Cardiac anomalies associated with RASopathies are characterized by the clinical phenotype of hypertrophic cardiomyopathy and manifest both as cardiac hypertrophy and congenital heart defects (pulmonary artery stenosis and coarctation of the aorta). Skin changes are not consistent and may develop later to the age 4-5 years old [2].

The prevalence of Noonan syndrome, an auto-somal dominant congenital disorder, ranges from 1:2500 to 1:1000 in newborns [1]. About 75% of NS patients have cardiac abnormalities among which the pulmonary artery stenosis is the most common variant. Hypertrophic cardiomyopathy is detected in 20% of the patients.

Aim - the present case reports of the successful heart transplantation due to rapidly progressive cardiac hypertrophy in a 3 year 8 month old girl diagnosed with Noonan syndrome.

Material and methods

Clinical and genetic study was performed based on Helsinki declaration. Parents had given a written consent for publication of the clinical description and open-face pictures. Clinical and instrumental examinations comprised regular general examination, electrocardiography, doppler echocardiography, 24-h Holter recording. Biochemical examination included general and biochemical testing of blood and urine, enzyme analysis, tandem mass spectrometry (TMS). Genetic testing involved chromosome analysis, or karyotype, and the search for mutations in the coding and adjacent intron regions of the LMNA, PTPN11 and RAF1 genes by Sanger direct capillary sequencing.

Clinical observation

Patient Ksenia N. (DOB 05/05 /2012) first entered the Perinatal Cardiology Center (PCC) of the City Clinical Hospital #67 in Moscow 4.5 months of age on 20.09.2012. It was known from her history that the child’s mother was 25 years old (with hereditary thrombophilia, the proband’s maternal grandmother had 10 years of infertility), the 4th pregnancy (1 pregnancy: m/a; 2 pregnancy: pre-term birth at 33-34 week, the child was born with congenital GI anomalies, operated; 3 pregnancy: frozen) complicated by thrombophilia, myopia, allergic rhinitis, the threat of interruption, colpitis, anemia, ARI. The woman during pregnancy received complex treatment forthe existing diseases. Second labor with elective induction at 39 weeks. Birth weight - 3000 g, length - 50 cm, head circumference - 34 cm, chest circumference - 33 cm. Cephalohematoma of the right parietal bone. A rough systolic murmur over the heart became noticeable 9 hours after birth. Echocardiogram conducted at the maternity hospital revealed echocardiographic signs of myocardial hypertro- phy. On the 5th day of life the infant was transferred from the maternity hospital to the State Children’s Hospital #1 in St. Petersburg. During the examination symmetrical obstructive hypertrophic cardiomyopathy (HCM) with outflow tract obstruction of both ventricles, grade 1-2 mitral regurgitation was revealed. Interventricular septum thick- ness: 15 mm; LV posterior wall thickness: 3 mm; LV/aortic pressure gradient: 35 mm Hg; combined pulmonary artery stenosis (PAS) with the pressure gradient between the pulmonary artery and the right ventricle of 70 mm Hg. The girl was examined for intrauterine infections (IUI), the data suggesting IUI were not found. From birth the infant had transient factor IX deficiency (at the age of 2 months IX factor: 37.1% (norm - 44-121%). For obstructive HCM the child was assigned to metoprolol.

When examined at the PCC, a moderately dysplastic phenotype with macrocrania, exophthalmos attracted attention (Fig. 1). There were symptoms of atopic dermatitis. The presence of HCM in combination with the phenotypic traits required the exclusion of both genetic syndromic pathology and inherited metabolic disorder. Karyotype: normal female - 46,XX. The absence of macroglossia, hyperferritinemia, myopathic syndrome with the symptomatic complex of “flaccid child” allowed to exclude Pompe disease (glycogenosis type II). The results of one- dimensional electrophoresis of glycosaminoglycans made in the laboratory of the Research Centre of Medical Genetics (Moscow, RU) showed no abnormalities which made it possible to exclude mucopolysaccharidosis in the girl. Tandem mass spectrometry (MS) excluded organic aciduria, hereditary aminoacidopathies, and defects of mitochondrial beta-oxidation. A slight increase in the concentration of 2-Hydroxybutyrateof homovanillic acid was of nonspecific character. Congenital pathology of the thyroid gland was excluded.

Cardiac examination at the PCC showed the presence of obstructive HCM with signs of progression of the pathological process. Echocardiogram from 24.09.2012: RV outflow tract (RVOT) pressure gradient: 80 mm Hg; left ventricular outflow tract (LVOT) gradient: 75 mm Hg. Left ventricular posterior wall thickness: 20мм; interventricular septum thickness: 18мм; RV anterior wall thickness: 13 mm. Because of symptoms of bronchial obstruction syndrome, beta-adrenergic antagonist metoprolol was replaced by atenolol, after that the wheezing in the lungs ceased to be heard. Verospiron was added to the treatment due to the signs of II A stage of circulatory failure.

Further dynamic observation indicated disease progression: a sleep disorder, shortness of breath, puffing while breathing. The girl gained weight badly, despite of good appetite. Diuretic therapy was strengthened by the addition of furosemide. At the age of 8 months RV outflow tract (RVOT) pressure gradient was around 100 mm Hg. DNA-based diagnostic testsmade it possible to exclude mutations in the LMNA gene (laminopathies) and Hutchinson-Gilford progeria syndrome (HGPS).

At the age of 10 months (March 2013) the child was quite active. The moderately dysplastic phenotype was preserved: a brachycephalic skull, macrocrania with a pronounced venous pattern, smaller facial features, larger eyes with Von Graefe’s sign, and low set ears. The girl was undernourished (body weight at admission - 6320 g, length - 69 cm, head circumference - 42 cm, chest circumference - 39 cm). Body weight deficiency in relation to height was 25% (second degree malnutrition). Muscular tone and skin turgor were reduced. Moderate dyspnea with respi- ration rate of 36-40 breathsper minute. Blood pressure - 90/60 mm Hg. Heart rate - 104-120 beats per minute. The borders of relative cardiac dullness were significantly expanded to the left: upper 2ICS; left along the left anterior axillary line; right along the right parasternal line. Heart sounds were sonorous, rhythmic, a tendency to bradycardia, rough systolic murmurs with chordalclicks over the whole heart with an epicenter in 2LICS conducting to the back were heard. All peripheral pulses were well palpable. The liver - +2.0 cm. The spleen - +2.0 cm. No teeth.

The child sat down, got up, walked with support, played with toys on her own, babbled.

The results of the cardiac examination did not reveal any cardiac rhythm disturbances in the infant, but there were signs of symmetric obstructive hypertrophic cardiomyopathy with LVEF - 91%; mitral valve regurgitation: grade 2; the left ventricular outflow gradient - 70 mm Hg; the right ventricular outflow gradient - 90 mm Hg. The stenoses were mainly infundibular in nature. The thickness of the myocardium did not undergo significant changes. A functioning ductus arteriosus with a left-to-right shunting of 3.5 mm, as well as sinusoids within the interventricular septum were detected. There was no effusion in the pericardial cavity (Fig. 2). Due to heart failure symptoms treatment with beta-blockers and diuretics was continued. During examination the child was diagnosed with microscopic hematuria without signs of urinary tract pathology according to ultrasound imaging.

Fig. 2. Echo-CG of patient K. at 4.5 months old. Obstructive HCM: А - B-mode; В - M-mode 

Ksenia N. has had some characteristic extra-cardiac features becoming more prominent with an age. Postnatal growth retardation was observed. Transitory micro-hematuria wasfoundalong witha normal renal ultrasound examination. Ksenia N.’s cognitive development was not impaired.

Genetic screening for the suspected inherited syndrome was continued in both clinics (Cincinnati, USA, and Moscow, RU). Mutationр. Gln510Glu in the PTPN11 gene was revealed (Fig. 3). Diagnosis of the Noonan syndrome was established based on clinical appearance and genetic data.

Thus, as a result of the comprehensive examination, the child was diagnosed with the following clinical diagnosis: Noonan syndrome. Symmetric obstructive hypertrophic cardiomyopathy. Mitral incompetence 2+, tricuspid valve regurgitation 1+. Patent arterial duct (PDA). Circulatory failure of IIa degree. ROSS functional class II. Protein-energy undernutri- tion (PEU) of the II degree.

Given the serious form of the disorder characterized by severe myocardial hypertrophy of both ventricles and interventricular septum with severe bilateral obstruction and increase in left and right ventricular outflow gradients, symptoms of heart failure, no response to conservative therapy, and high risk of sudden death syndrome, on July 22, 2013 Ksenia N. entered the Heart Institute at Cincinnati Children’s Hospital Medical Center (Ohio, USA) where the ques- tion of performing auxiliary surgery for the existing diseases was considered.

A comprehensive examination showed the impossibility of surgical correction of the existing disorders and the inexpediency of such intervention. Echocardiogram recorded the following parameters: LVED - 2.57 cm; LVES - 0.71 cm; RVED - 1.54 cm; the peak left ventricular outflow gradient - 121 mm Hg; the systolic gradient - 58 mm Hg; the peak right ventricular gradient - 107 mm Hg. Almost complete obliteration of the right ventricle cavity during systole. Interventricular septum thickness in diastole (IVSd) - 19 mm; interventricular septum thickness in systole (IVSs) - 23 mm; LV posterior wall thickness in diastole - 14.6 mm; LV posterior wall thickness in systole(LVPWs) - 22.7 mm. The ratio of inter-ventricular septum to left posterior ventricular wall thickness - 1.31. Grade 2 mitral regurgitation, grade 1 aortic insufficiency, grade 1 pulmonary valve insufficiency, moderate left atrial enlargement, hyperdynamic myocardial function. LVEF - 73%. LV mass - 161.62 g, LV mass index - 311.2 g/m2. The ductus arteriosus with left-to-right shunt of blood flow. Absence of pericardial effusion. Accordingly, the child had HCM with severe right and left ventricular outflow tract obstruction, moderate mitral valve regurgitation with left atrial dilation, and patent ductusarteriosus.

It was decided that heart transplantation was the only way to provide real assistance to this patient. The girl was put on the UNOS heart transplant waiting list in 2013 (status 1B). Preoperative preparation involved genetic testing, nutritional correction, compulsory preventive vaccination, treatment of dental caries, and continuation of drug therapy for severe right and left ventricular outflow tract obstruction. The waiting period for the organ transplant was 2.5 years. During the whole waiting period the child’s condition was regarded as very serious. On the 29th January, 2016 Ksenia N. (3 y. 8 m. old) underwent orthotopic heart transplantation at the Heart Institute of Cincinnati Children’s Hospital Medical Center (Ohio, USA). The surgery and the nearest post-operative period proceeded without complications. During histological examination Parvovirus B19 was found both in the native and donor hearts. Appropriate treatment with intravenous immunoglobulin was carried out. During 2016 and up to now the child has received complex immunosuppressive therapy according to the scheme [the calcineurin inhibitor tacrolimus, antiproliferative agent CellCept® (mycophenolatemofetil), corticosteroid prednisolone] under the control of regularly conducted catheterizations and endomyocardial biopsies. There were no signs of rejection and changes in the coronary arteries of the donor heart in the postoperative period (outcome 1A). To prevent dental caries antimicrobial therapy was prescribed to the infant. After surgery the girl’s condition has significantly improved: motor activity has increased (she is learning to ride a scooter, skates, and a bicycle), her appetite has normalized, microcirculatory flow has been improved (warm limbs, pink lips). The child has gained weight which may be partly caused by corticosteroids. She has a growth delay: a typical sign of Noonan syndrome. Examination reveals mild pericardial and pleural effusions. It cannot be ruled out that these changes are also due to the side effects associated with glucocorticoid administration.

It was one year after cardiac transplantation on 29.01.2017 (Fig. 4). The child up to the present time has lived and been observed at the Heart Institute of Cincinnati Children’s Hospital Medical Center (Ohio, USA). In May 2017 the girl turns 5 years old.

Fig. 4. 1 year after heart transplantation 

Discussion

Mutation p. Gln510Glu in the PTPN11 gene was first described in patients with Noonan syndrome and rapidly progressive HCM in 2005 [3]. Later this mutation was also found in patients with rapidly progressive severe biventricular obstructive HCM, ventricular arrhythmias, mitral valve defects, facial dysmorphic features, “cafe-au-lait” spots, and multiple lentigines corresponding to the LEOPARD syndrome [4, 5].

Noonan and LEOPARD syndromes caused by mutations in the PTPN11 gene are allelic disorders, and share most of phenotypic features including high prevalence of the cardiac hypertrophy [6].

The myocardial hypertrophy in Ksenia N.’s case was also severe, symmetrical, and obstructive. The results of the cardiac examination conducted both at the Perinatal Cardiology Center in Moscow and the Heart Institute of Cincinnati Children’s Hospital Medical Center, and previous clinical descriptions have completely coincided pointing out the stability of cardiac phenotype and severe prognosis for the carriers of thep. Gln510Glu mutation.

Remarkably that thisp. Gln510Glu mutation in the PTPN11 gene was found in patients with different clinical phenotype, with Noonan syndrome with and without multiple lentigines, and clear LEOPARD syndrome [3-5].

Genotype-phenotype correlations in Noonan syndrome and other RASopathies are now being actively studied. The prevalence rate of HCM in LS has been reported to be much higher than that in NS (70-80% versus 10-25%) [7]. It was shown mutation in the PTPN11 gene leading to the NS usually enhance Erk pathway [8]. On the other hand, LEOPARD syndrome mutations almost exclusively impair catalytic activity of the PTPN11 [9]. Two independent research groups had studied functional effects of the p. Gln510Glu mutation, and it seems that mutant protein share those properties [7, 10].

This clinical observation is more consistent with Noonan syndrome phenotype at the moment. But we cannot exclude that additional clinical feature as skin involvement might appear in our patient later.

The future perspective of the therapy could be a gene-specific treatment approach. The promising results of the target inhibition of RAS/MAPK pathway was shown in transgenic mice harboring dominant- negative p. Y279C mutation in the PTPN11 gene treated by rapamicyne [9]. Rapamicyne inhibits Akt/mTOR pathway which is usually up-regulated in LEOPARD syndrome model cells, and it was shown to completely reverse cardiac hypertrophy inLSmut+/- mice [9]. The single case of the successful palliative treatment of the Noonan syndrome infant with rapidly progressive cardiac hypertrophy with everolimus (a rapamicyne analogue) was published recently [11].

Conclusion

It suggests that mutation-specific RAS/MAPK pathway inhibition might be considered for patients with RASopathies at least as a bridge therapy before heart transplantation. Further study is needed to analyze better short-term and long-term results of the treatment with ramapicyne and analogues. But for now the heart transplantation is the only proven option for pediatric patients with rapidly progressing cardiac hypertrophy.

Acknowledgements

The authors thank the parents of the patient for their cooperation and permission to publish data and pictures. 

Литература 

 1. Marin T.M., Keith K., Davies B., et al. Rapamycin reverses hypertrophic cardiomyopathy in a mouse model of LEOPARD syndrome-associated PTPN11 mutation. J Clin Invest. 2011; 121 (3): 1026-43.

2. Takahashi K., Kogaki S., Kurotobi S., et al. A novel mutation in the PTPN11 genein a patient with Noonan syndrome and rapidly progressive hypertrophic cardiomyopathy. Eur J Pediatr. 2005; 164 (8): 497-500.

3. Digilio M.C., Sarkozy A., Pacileo G., et al. PTPN11 gene mutations: linking the Gln510Glu mutation “LEOPARD syndrome pheno- type”. Eur J Pediatr. 2006; 165 (11): 803-5.

4. Hahn A., Lauriol L., Thul J., et al. Rapidly progressive hypertrophic cardiomyopathy in an infant with noonan syndrome with multiple lentigines. Palliative treatment with a rapamycin analog. Am J Med Genet A. 2015; 0 (4): 744-51.

5. Wakabayashi Y., Yamazaki K., Narumi Y., et al. Implantable cardioverter defibrillator for progressive hypertrophic cardiomyopathy in a patient with LEOPARD syndrome and a novel PTPN11 mutation Gln510His. Am J Med Genet A. 2011; 155A (10): 2529-33.

6. Ganigara M., Prabhu A., Kumar R.S. LEOPARD syndrome in an infant with severe hypertrophic cardiomyopathy and PTPN11 muta- tion. Ann Pediatr Cardiol. 2011; 4 (1): 74-6.

7. Faienza M., Giordani L, Ferraris M., et al. PTPN11 gene mutation and severe neonatal hypertrophic cardiomyopathy: what is the link? Pediatr Cardiol. 2009; 30 (7): 1012-5.

8. Aoki Y., Niihori T., Inoue Sh.-I. et al. Recent advances in RA- Sopathies. J Hum Gen. 2016; 61: 33-9.

9. Keilhack H., David F., McGregor M., et al. Diverse biochemical properties of Shp2 mutants. Implications for disease phenotypes. J Biol Chem. 2005; 280 (35): 30984-93.

10. Ishida H., Kogaki S., Narita J., et al. LEOPARD-type SHP2 mutant Gln510Glu attenuates cardiomyocyte differentiation and promotes cardiac hypertrophy via dysregulation of Akt/GSK-3β/ β-catenin signaling. Am J Physiol Heart Circ Physiol. 2011; 301 (4): H1531-9.

11. Schramm C., Fine D., Edwards M., et al. The PTPN11 loss-of- function mutation Q510E-Shp2 causes hypertrophic cardiomyopathy by dysregulating mTOR signaling. Am J Physiol Heart Circ Physiol. 2012; 302 (1): H231-43.