Noonan-like syndrome with loose anagen hair: three clinical cases

Noonan-like syndrome with loose anagen hair is a rare inherited disease caused by heterozygous mutation in the  SHOC2  gene. The disease was first described in 1991. The main clinical manifestations of the disease are phenotype features similar to those observed in Noonan syndrome: orbital hypertelorism, eyelid ptosis, low-set, and posteriorly rotated auricles, as well as skin and hair lesions, development delay, loose anagen hair, cardiovascular disorders, and mental retardation. It has an autosomal dominant mode of inheritance. We have described three clinical cases of this disease for the first time in Russia. All children in this group had a Noonan-like phenotype, macrocephaly, wide, short neck, hair and skin lesions, congenital heart disease, development delay of different severity, and hypotonia. One child had hypertrophic cardiomyopathy, nonobstructive form, aneurysmal dilatation of interatrial septum, minor dilation of the pulmonary artery and atria, apical aneurysm other cases showed a congenital defect of the urinary system. These patients have thin, sparse, slowly growing hair, dark skin. One girl was diagnosed with multiple capillary haemangiomas on her head and trunk. Pathogenic nucleotide variant c.4A>G, p.S2G in heterozygous state of the SHOC2 gene was revealed in all our patients. The same was described previously in patients with this syndrome. Differential diagnosis at suspicion on Noonan-like syndrome with loose anagen hair should be carried out with Noonan syndrome, Cardiofaciocutaneous syndrome (CFC), Costello syndrome.