Congenital central hypoventilation syndrome (CCHS)is a rare disorder characterized by hypoventilation during sleep and blunted ventilatory responses to hypercapnia and hypoxemia.It is normally found in neonatal and infant.Late-onset cases have been reported recently.The paired-like homeobox gene PHOX2B is the disease-defining gene for CCHS;a mutation in the PHOX2B gene is requisite to the diagnosis of CCHS.As a lifelong disease,the key treatment is ensuring adequate ventilation and oxygenation,effective modalities include positive pressure ventilation,negative pressure ventilation and diaphragmatic pacing.The strategy of anti-mutant protein and the use of progestin open up clinical perspectives to enhance ventilation in CCHS patients.

Rett syndrome ( RTT) is a devastating neurological disorder that is caused largely by muta-tions in the X-linked gene MECP2,other two genes associated with RTT are CDKL5 and FOXG1. RTT is one of the most common causes of mental retardation in girls,male cases are rare. Classical features of typical RTT in-clude losing acquired spoken language and hand skills,hand stereotypies,epilepsy and respiratory disorders. The diagnosis of RTT mainly depends on the clinical characteristics. Atpresent, it still lacks atargeted treatment. In this review,we summarize both the gene research,diagnosis and treatmentprogresses of RTT so as to improve the understanding of RTT.

Exosomes are some small membrane-bound vesicles released by cells into extracellular spaces.They carry a variety of bioactive molecules, such as proteins, RNA and lipids for material exchange and communication in cells.Exosomes have been recognized as an important pathway in the nervous system in both normal and disease settings.Meanwhile, exosomes can pass through the blood-brain barrier.Therefore, exosomes provide a new strategy for the diagnosis and treatment of central nervous system diseases.In this review, general characteristics of exosomes, pathological and physiological functions of exosomes in central nervous systems and the progress of exosomes applied to the diagnosis and treatment of central nervous system diseases are discussed.