What Is Phenylketonuria? Phenylketonuria (PKU) is a common autosomal recessive monogenic metabolic disorder caused by pathogenic variants in the phenylalanine hydroxylase (PAH) gene. Mutations impair the function of PAH enzyme, blocking normal phenylalanine (Phe) catabolism and resulting in systemic accumulation…

What Is Angelman Syndrome? Angelman Syndrome (AS) is a neurodevelopmental disorder triggered by dysfunction of the maternally inherited UBE3A gene located on chromosomal region 15q11–13. Its hallmark clinical manifestations include severe developmental delay, intellectual disability, persistent happy demeanor, speech impairment,…

What Is Rett Syndrome? Rett Syndrome (RTT) is a severe neurodevelopmental disorder caused by loss-of-function variants in the MECP2 gene located on the X chromosome, predominantly affecting female patients. Clinical manifestations typically emerge between 6 and 18 months of age…

What Is Fibrodysplasia Ossificans Progressiva? Fibrodysplasia Ossificans Progressiva (FOP), also known as “Stone Man Syndrome”, is an ultra-rare hereditary connective tissue disorder. Its hallmark clinical features include congenital bilateral great toe malformation, together with progressive, widespread and irreversible heterotopic ossification…

What Is Paroxysmal Nocturnal Hemoglobinuria? Paroxysmal Nocturnal Hemoglobinuria (PNH) is a rare acquired clonal disorder of hematopoietic stem cells. Its classic clinical triad consists of three core manifestations: Most PNH patients die from thrombosis or progressive cytopenia. The disease incidence…

What Is Marfan Syndrome? Marfan Syndrome (MFS) is an autosomal dominant connective tissue disorder that affects multiple organ systems, primarily the skeletal, ocular, and cardiovascular systems. Typical clinical manifestations include arachnodactyly, scoliosis, lens dislocation, high myopia, and the most life-threatening…

What Is Hepatolenticular Degeneration? Hepatolenticular Degeneration, also known as Wilson Disease (WD), is a rare autosomal recessive genetic disorder caused by mutations in the ATP7B gene, which leads to abnormal copper accumulation in organs including the liver, brain and cornea.…

Achondroplasia (ACH) is a common genetic skeletal dysplasia. Its core clinical manifestations include disproportionate short stature, macrocephaly with frontal bossing, midface hypoplasia, and bowed tibia. The incidence ranges from 1 in 15,000 to 1 in 25,000 live births. Pathogenesis The…

Albinism is a rare hereditary disorder. It is primarily caused by the deficiency or dysfunction of tyrosinase, which disrupts melanin synthesis and leads to pigment loss in the skin, hair and eyes. Without the protection of melanin, patients are vulnerable…

Cystic fibrosis is an autosomal recessive rare hereditary disorder triggered by pathogenic mutations in the CFTR gene located on the long arm of human chromosome 7. Gene defects impair chloride transport across epithelial cells and trigger excessive sodium & water…