Jordan's syndrome
Other namesPPP2R5D-related intellectual disability, mental retardation, autosomal dominant 35(MRD35)
SpecialtyPsychiatry, pediatrics, occupational medicine, neurology, ophthalmology
SymptomsMild to severe global developmental delay, seizure, macrocephaly, hypotonia, autism, dysmorphic facial features
DurationLifelong
CausesHeterozygous PPP2R5D mutation
Diagnostic methodMolecular genetic testing
Differential diagnosisCowden syndrome, Sotos syndrome, Smith-Kingsmore syndrome, M-CM, MPPH, 9q34 deletion syndrome, 16p11.2 deletion syndrome
ManagementOccupational therapy, physical therapy, speech therapy, applied behavior analysis
Frequency23 (2019)[1]

Jordan's Syndrome (JS) or PPP2R5D-related intellectual disability is a rare autosomal dominant neurodevelopmental disorder caused by de novo mutations in the PPP2R5D gene.[2] It is characterized by hypotonia, intellectual disability, and macrocephaly.[3] Children with JS may also have epilepsy or meet criteria for diagnosis with autism spectrum disorder.[4]

Signs and symptoms

Symptoms of Jordan's Syndrome (JS) are not formally defined but typically appear in early childhood and can range from mild to severe global developmental delay and intellectual disability, usually including speech delay and impairment.[5][1] Patients with JS may meet some or all criteria for diagnosis with autism spectrum disorder due to many shared developmental symptoms.[4] Initial clinical findings may include macrocephaly, hypotonia, epilepsy, ophthalmologic abnormalities, and dysmorphic facial features. Magnetic resonance imaging may further reveal megalencephaly or defects of the ventricles or white matter. Individuals with JS may also have skeletal, cardiac, endocrine, or genital abnormalities.[1] Certain JS mutations can also cause early-onset parkinsonism between ages 20-40.[6]

Genetics

All cases of JS are caused by de novo missense point mutations in PPP2R5D, which encodes a subunit of the enzyme PP2A. At least 8 different pathogenic mutations have been identified: E197K, E198K, E200K, E420K, P201R, W207R, Q211P, and P53S.[7]

Patients are exclusively diagnosed with JS upon discovery of a pathogenic variant of PPP2R5D via genetic testing.[3][4] As of 2019, at least 23 individuals with JS have been reported.[1]

Mechanisms

The molecular mechanisms underlying JS are unknown. Broadly, PP2A dysfunction is known to be associated with other pathologies such as Alzheimer's disease, Parkinson's disease, and cancer.[7] Studies of specific JS-causing variants such as E420K have implicated PI3K/AKT/mTOR pathway dysregulation in JS pathogenesis.[5]

Diagnosis

Jordan's Syndrome is diagnosed through molecular genetic testing, most commonly exome sequencing.[2]

Research

PPP2R5D-related intellectual disability was named "Jordan's Syndrome" after Jordan Lang, who was diagnosed by whole exome sequencing in 2014.[8] Lang's parents founded the charitable organization Jordan's Guardian Angels to connect families of individuals with JS. The foundation also funds PPP2R5D research, spanning diverse model systems from alpacas and fruit flies[9] to patient-derived induced pluripotent stem cells.[10] Ten primary investigators are affiliated with the foundation:[11]

References

  1. 1 2 3 4 Mirzaa G, Foss K, Nattakom M, Chung WK (24 January 2019). "PPP2R5D-Related Neurodevelopmental Disorder". In Adam MP, Ardinger HH, Pagon RA, Wallace SE, Bean LJ, Mirzaa G (eds.). GeneReviews®. Seattle, WA: University of Washington. PMID 30676711.
  2. 1 2 "PPP2R5D-related intellectual disability". MedlinePlus. 1 February 2021. Retrieved 2021-10-01.
  3. 1 2 Yan, Lulu; Shen, Ru; Cao, Zongfu; Han, Chunxiao; Zhang, Yuxin; Liu, Yingwen; Yang, Xiangchun; Xie, Min; Li, Haibo (2021-02-12). "A Novel Missense Variant in the Gene PPP2R5D Causes a Rare Neurodevelopmental Disorder with Increased Phenotype". BioMed Research International. 2021: 1–7. doi:10.1155/2021/6661860. PMC 7895568. PMID 33628804.
  4. 1 2 3 Shang, Linshan; Henderson, Lindsay B.; Cho, Megan T.; Petrey, Donald S.; Fong, Chin-To; Haude, Katrina M.; Shur, Natasha; Lundberg, Julie; Hauser, Natalie; Carmichael, Jason; Innis, Jeffrey (2016-01-01). "De novo missense variants in PPP2R5D are associated with intellectual disability, macrocephaly, hypotonia, and autism". Neurogenetics. 17 (1): 43–49. doi:10.1007/s10048-015-0466-9. ISSN 1364-6753. PMC 4765493. PMID 26576547.
  5. 1 2 Papke, Cinta M.; Smolen, Kali A.; Swingle, Mark R.; Cressey, Lauren; Heng, Richard A.; Toporsian, Mourad; Deng, Liyong; Hagen, Jacob; Shen, Yufeng; Chung, Wendy K.; Kettenbach, Arminja N. (January 2021). "A disorder-related variant (E420K) of a PP2A-regulatory subunit (PPP2R5D) causes constitutively active AKT-mTOR signaling and uncoordinated cell growth". Journal of Biological Chemistry. 296: 100313. doi:10.1016/j.jbc.2021.100313. ISSN 0021-9258. PMC 7952134. PMID 33482199.
  6. ↑ Kim CY, Wirth T, Hubsch C, Németh AH, Okur V, Anheim M, et al. (2020). "Early-Onset Parkinsonism Is a Manifestation of the PPP2R5D p.E200K Mutation". Ann Neurol. 88 (5): 1028–1033. doi:10.1002/ana.25863. PMC 9052555. PMID 32743835. S2CID 220943402.
  7. 1 2 Biswas, Dayita; Cary, Whitney; Nolta, Jan A. (January 2020). "PPP2R5D-Related Intellectual Disability and Neurodevelopmental Delay: A Review of the Current Understanding of the Genetics and Biochemical Basis of the Disorder". International Journal of Molecular Sciences. 21 (4): 1286. doi:10.3390/ijms21041286. PMC 7072873. PMID 32074998.
  8. ↑ "The History of Jordan's Syndrome". Jordan's Guardian Angels. Retrieved 2021-10-01.
  9. 1 2 Turney, Spencer (13 August 2019). "Meet the alpacas that are helping researchers who study autism, Alzheimer's and cancer". Vanderbilt University. Retrieved 2021-10-01.
  10. 1 2 3 "On a mission: $12 million state appropriation earmarked for Jordan's syndrome". 25 July 2018. Retrieved 2021-10-01.
  11. ↑ "Our Research Team". Jordan's Guardian Angels. Retrieved 2021-10-01.
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