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Paroxysmal bursts of laughter

MedGen UID:
Concept ID:
Synonyms: Frequent laughing or smiling; Paroxysmal laughter
HPO: HP:0000749

Term Hierarchy

CClinical test,  RResearch test,  OOMIM,  GGeneReviews
  • CROGParoxysmal bursts of laughter

Conditions with this feature

Angelman syndrome
MedGen UID:
Concept ID:
Disease or Syndrome
Angelman syndrome (AS) is characterized by severe developmental delay or intellectual disability, severe speech impairment, gait ataxia and/or tremulousness of the limbs, and a unique behavior with an inappropriate happy demeanor that includes frequent laughing, smiling, and excitability. Microcephaly and seizures are also common. Developmental delays are first noted at around age six months; however, the unique clinical features of AS do not become manifest until after age one year, and it can take several years before the correct clinical diagnosis is obvious.
Mental retardation-hypotonic facies syndrome X-linked, 1
MedGen UID:
Concept ID:
Disease or Syndrome
The term 'X-linked mental retardation-hypotonic facies syndrome' comprises several syndromes previously reported separately. These include Juberg-Marsidi, Carpenter-Waziri, Holmes-Gang, and Smith-Fineman-Myers syndromes as well as 1 family with X-linked mental retardation with spastic paraplegia. All these syndromes were found to be caused by mutation in the XH2 gene and are characterized primarily by severe mental retardation, dysmorphic facies, and a highly skewed X-inactivation pattern in carrier women (Abidi et al., 2005). Other more variable features include hypogonadism, deafness, renal anomalies, and mild skeletal defects. X-linked alpha-thalassemia/mental retardation syndrome (ATR-X; 301040) is an allelic disorder with a similar phenotype with the addition of alpha-thalassemia and Hb H inclusion bodies in erythrocytes.

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