Gonadal function in Noonan syndrome

Noonan syndrome (NS) is a relatively common developmental disorder characterised by the association of craniofacial abnormalities, congenital heart defects, short stature and skeletal abnormalities, variable developmental delay/learning disability, and predisposition to certain cancers. NS is caused by germline mutations in genes encoding components or regulators of the RAS/mitogen-activated protein kinase (MAPK) signaling pathway. Although abnormalities in the hypothalamic-pituitary-gonadal axis have long been reported in NS patients, there is only scarce published data on this subject. Puberty is usually delayed of about two years for both boys and girls with NS. However, in the majority of patients, it starts spontaneously suggesting a normal hypothalamic-pituitary input. The lower fat mass usually observed in NS patients may influence the timing of puberty. Although there is almost no reliable data on this issue, it is usually considered that fertility is not affected in NS females. In contrast, primary testicular insufficiency, predominant on Sertoli cell function, is reported in NS males. However, the exact frequency of infertility in adult males is unknown. More generally, although the features of NS are well described during childhood, little is known about the progression of the disease in adulthood. Prospective long-term follow-up studies are required to further investigate gonadal function and fertility in NS adults and to clarify the long-term follow-up of these patients.

Coronary artery disease in adults with Noonan syndrome: Case series and literature review

Noonan syndrome (NS) is a genetic disorder characterized by facial dysmorphism, congenital heart disease, and short stature. In very rare cases, patients with this syndrome have coronary disease. Their management and prognosis are currently unclear. We have described 4 cases of coronary aneurysms/coronary ectasia and 1 case of a single coronary artery in patients with adult Noonan syndrome, followed in a medical and surgical center of adult congenital heart disease. The average age was 49.4years old. The majority of them had both pulmonary stenosis and interauricular communication. None had symptoms of angina, at rest, or with stress. Only one patient who had any structural heart disease, had a thrombotic complication with chronic occlusion of the right coronary and anterior inter ventricular artery, fortuitous finding, with no ischemic signs to functional tests, treated only with anti-vitamin K. Finally, any deaths have also been reported in our series. Coronary artery diseases essentially coronary aneurysm/ectasia remain a rare condition in adult patients with NS. Evolution is unknown and complications such as coronary artery thrombosis do not necessarily require surgical treatment.

[Multiple granular cell tumours in a patient with Noonan's syndrome and juvenile myelomonocytic leukaemia]

BACKGROUND

Granular cell tumour (GCT) is a rare form of tumour comprising Schwann cells. Herein, we report a case of a child presenting Noonan syndrome complicated by juvenile myelomonocytic leukaemia (JMML) and who also developed a multiple form of GCT. We discussed the molecular mechanisms that might account for this association.

PATIENTS AND METHODS

A six-year-old boy with Noonan syndrome complicated by JMML presented three asymptomatic subcutaneous nodules on his back, forearm and neck. Histological analysis revealed GCT. A literature review revealed seven cases of Noonan syndrome presenting GCT, none of which were associated with JMML. Mutation of gene PTPN11, via hyperactivation of intracellular Ras signalling may cause the development of GCT and JMML in children presenting Noonan syndrome.

DISCUSSION

Detailed clinical examination is recommended in children presenting GCT to screen for multiple forms and for signs of malformation suggestive of a genetic syndrome. Ours is the first case to be described of Noonan syndrome complicated by JMML associated with multiple GCT. This association once again raises the important question of the role of the Ras-MAPK signalling pathway in the development of benign and malignant tumours of solid organs or blood, associated with genetic syndromes.

[Enigmatic lymphatic diseases involving the lung]

Lymphedema associated with other developmental malformations (Milroy syndrome, Hennekam syndrome, Noonan syndrome, Gorham-Stout syndrome, yellow nail syndrome) are unfrequent disease, but explorations led to the identification of genetic mutations that have then been validated in mouse models. However, lymphatic vessels complexity and its proximity with the venous system suggest the need for further researches, especially in the comprehension of pulmonary symptoms.