What is Angelman Syndrome? Angelman Syndrome (AS), also known as Angelman syndrome, is a neurodevelopmental disorder caused by abnormalities in the maternal allele of the UBE3A gene located in the 15q11-13 chromosomal region. Its main characteristics include severe developmental delay, intellectual disability, a happy demeanor with frequent laughter, language impairment, ataxia, and seizures. The incidence of AS is approximately 1 in 20,000 to 1 in 12,000.

What is Phenylketonuria? Phenylketonuria (PKU) is a common monogenic inherited disorder, classified as an autosomal recessive genetic condition. It is caused by mutations in the phenylalanine hydroxylase (PAH) gene, leading to congenital metabolic dysfunction that prevents normal metabolism of phenylalanine (Phe), resulting in its accumulation in the blood and organs. PKU patients typically exhibit severe developmental delay, neurological deficits, behavioral abnormalities, and epileptic seizures. In China, the overall incidence of PKU is approximately 1 in 11,000, with higher prevalence in northern populations compared to southern regions.

Pulmonary Alveolar Proteinosis (PAP) is a rare disease characterized by abnormal accumulation of surfactant material within the alveoli, primarily classified into acquired (autoimmune), congenital, and secondary types. Among these, autoimmune PAP (also known as idiopathic or adult-onset PAP) is the most common, accounting for approximately 90% of all cases. The typical clinical presentation includes insidiously progressive dyspnea, which may be accompanied by dry cough or scanty frothy sputum. Imaging often reveals diffuse "crazy-paving" or ground-glass opacities. Epidemiological data indicate that the prevalence of this disease is approximately 6.87 cases per million population.

Hypophosphatemic Rickets (HR) is a relatively rare disease with an incidence of approximately 1 in 25,000. It is primarily caused by genetic or acquired factors leading to excessive renal phosphate excretion, resulting in severely low blood phosphate levels and impaired bone mineralization. In childhood, it manifests as frontal bossing, pigeon chest, rachitic rosary, limb deformities (bowlegs or knock-knees), growth retardation, short stature, waddling gait, and dental abnormalities (enamel defects, recurrent dental abscesses). In adulthood, symptoms include bone pain, muscle weakness, multiple fractures, height loss, and restricted mobility.

What is Multiple Sclerosis? Multiple Sclerosis (MS) is a chronic immune-mediated disease characterized by multifocal inflammatory demyelination, axonal degeneration, and glial scar formation in the Central Nervous System (CNS). Clinical manifestations include cognitive decline, fatigue, muscle weakness, sensory abnormalities, ataxia, and progressive neurological disability. With approximately 2.8 million patients globally, MS predominantly affects young adults aged 20-40 and is the leading cause of non-traumatic neurological disability in this age group.Based on its natural history, MS is classified into four phenotypes: Relapsing-Remitting MS (RRMS, 80%), Secondary Progressive MS (SPMS), Primary Progressive MS (PPMS, 10%~15%), and Progressive Relapsing MS (PRMS, <5%).