Halpein-Birk syndrome
Other namesHLBKS
SpecialtyNeurodevelopmental
SymptomsIntrauterine growth retardation, developmental delay, spastic quadriplegia with profound contractures, dysmorphism, microcephaly and agenesis of the corpus callosum
Usual onsetCongenital
CausesSEC31 gene LOF mutation
PrognosisEarly lethality

Halperin-Birk syndrome (HLBKS) is a rare autosomal recessive neurodevelopmental disorder caused by a null mutation in the SEC31A gene. Signs and symptoms include intrauterine growth retardation, marked developmental delay, spastic quadriplegia with profound contractures, dysmorphism, and optic nerve atrophy with no eye fixation. Brain MRI demonstrated microcephaly and agenesis of the corpus callosum.[1]

The syndrome was first described in 2019 by Daniel Halperin and Prof. Ohad Birk at the Morris Kahn Laboratory for Human Genetics, Ben Gurion University of the Negev.

Signs and symptoms

Source:[1]

Inheritance

  • Autosomal recessive
Autosomal recessive inheritance

Growth

  • Intrauterine growth retardation
  • Failure to thrive

Head & neck

  • Head
  • Face
  • Ears
    • Hearing impairment
  • Eyes
    • Cataracts, congenital
    • Optic atrophy
    • Lack of fixation
    • Visual impairment
    • Long eyelashes
  • Mouth
    • High-arched palate Thick lips

Respiratory

  • Recurrent aspiration

Gastrointestinal

Skeletal

Muscle, soft tissues

Neurologic

Causes

Halperin-Birk syndrome describes a severe autosomal recessive neurodevelopmental disorder caused by a loss of function mutation in SEC31A, a component of the coat protein complex II (COP-II). SEC31A (transcript variant 1; NM_ 001318120), also known as KIAA0905 and SEC31-related protein A (SEC31L1), encodes the transport protein SEC31A, a 1220 amino acid protein that is highly conserved through evolution. It contains multiple WD repeats near the N-terminus and conserved proline-rich region in its C-terminal.[2] SEC31A is a component of the COPII protein complex, responsible for vesicle budding from the Endoplasmic Reticulum (ER). It has been demonstrated to be highly expressed in the notochord, optic tectum, otic vesicle, cleithrum, and fin during embryogenesis.[3] Its importance to neuronal and craniofacial development has been demonstrated mainly through its efficient coupling with SEC13 and the SEC23-SEC31A interface. Failure to recruit SEC31A results in severe secretion defects of procollagen, and an enlarged ER, in line with aberrant protein secretion.

Mechanism

The COP-II complex comprises five highly conserved proteins, among these SEC31A, creating small membrane vesicles that originate from the ER.[4][5] Budding of these vesicles is essential in the cellular trafficking pathway, through which membrane and luminal cargo proteins are transported from their site of synthesis to other cellular compartments.[6] This machinery assembles hierarchically, driven by the initial recruitment and activation of the small GTPase SAR1, which exists in a soluble cytoplasmic form when in its GDP-bound state.[7] SAR1 is promoted by SEC12, a membrane-bound GEF that catalyzes GDP/GTP exchange.[8] Once tightly anchored into the ER membrane, the active GTP-bound SAR1 recruits the SEC23-SEC24 heterodimer to form the inner “pre-budding” complex, capable of engaging cargo through interactions between SEC24 and multiple ER export motifs.[9][10] Finally, the SEC13–SEC31A hetero-tetramer is recruited to promote coat polymerization, membrane curvature, and eventually membrane fission.[11][12] With the full complement of the COP-II complex, the extruded membrane is separated from the ER membrane to form an intact vesicle.[13]

Most mammalian COP-II complex subunits have one or more paralogues with partially redundant functions, as the loss of selected copies often results in a genetic disease.[14] The mammalian repertoire consists of two SAR1 paralogs, SAR1A and SAR1B; two SEC23 paralogs, SEC23A and SEC23B; four SEC24 paralogs, SEC24A, SEC24B, SEC24C, and SEC24D; a single SEC13 and two SEC31 paralogs: SEC31A, comprising part of the SEC13/SEC31 hetero-tetramer, and SEC31B. The repertoire of COP-II paralogs available in mammals could contribute to a wide variety of COP-II coats, thus facilitating selective cargo transport in a tissue-specific manner. Alternative splicing could further contribute to the COP-II vesicle and cargo selection diversity.[15]

Associated diseases/phenotypes with mutations in the COP-II complex genes described to date (2021)
Yeast COP-II Mammalian COP-II Organism Associated disease/phenotypes OMIM
SAR1p SAR1A
SAR1B Human Chylomicron retention (CMRD)/Anderson's disease 246700
SEC23p SEC23A Human Cranio-lenticulo-sutural dysplasia (CLSD) 607812
Zebrafish Skeletal and craniofacial development defects
SEC23B Human Congenital dyserythropoietic anemia type II (CDAII) 610512
Zebrafish Aberrant erythrocyte development
SEC24p SEC24A Arabidopsis thaliana Secretory and Golgi proteins accumulate in ER
SEC24B Mice Neural tube defects and craniorachischisis
SEC24C Mice Embryonic lethality
SEC24D Human Osteogenesis imperfecta-like syndrome 607186
Zebrafish Craniofacial dysmorphology, defects in trafficking of ECM proteins including type II collagen
Medaka Skeletal and facial development defects
Mice Early embryonic lethality
SEC13p SEC13 Zebrafish Defects in proteoglycan deposition cause CLSD-like phenotype
SEC31p SEC31A Human Halperin-Birk syndrome 618615
SEC31B

Molecular genetics

CRISPR/Cas9-mediated knockdown of the SEC31A gene in human SH-SY5Y neuroblastoma cells resulted in the failure of the cells to expand to generate viable clones. In addition, knockdown of the gene in HEK293 cells increased susceptibility to ER stress compared to controls. These results suggest that enhanced ER stress response is likely part of the molecular mechanism of the human disease.[1]

Diagnosis

There is no specific test to diagnose HLBKS other than exome/genome sequencing.[1]

Treatment

Currently, there are no genetic therapies specifically targeting the underlying cause of HLBKS. However, following the identification of the syndrome, a preimplantation genetic diagnosis (PGD) can be offered when one or both genetic parents are carriers of a mutation in this gene.[1]

Research

Animal model

In-vivo C. elegans experiments have demonstrated that SEC31A-deficient mutants are embryonically lethal due to various developmental defects.[16] Halperin et al. (2019) found that complete loss of Sec31a in Drosophila was embryonically lethal and associated with eye and brain development defects, consistent with abnormal neurodevelopment.[1]

References

  1. 1 2 3 4 5 6 Halperin, Daniel; Kadir, Rotem; Perez, Yonatan; Drabkin, Max; Yogev, Yuval; Wormser, Ohad; Berman, Erez M.; Eremenko, Ekaterina; Rotblat, Barak; Shorer, Zamir; Gradstein, Libe (2019-03-01). "SEC31A mutation affects ER homeostasis, causing a neurological syndrome". Journal of Medical Genetics. 56 (3): 139–148. doi:10.1136/jmedgenet-2018-105503. ISSN 0022-2593. PMID 30464055. S2CID 53717389.
  2. ↑ Tang, Bor Luen; Zhang, Tao; Low, Delphine Y.H.; Wong, Ee Tsin; Horstmann, Heinrich; Hong, Wanjin (May 2000). "Mammalian Homologues of Yeast Sec31p". Journal of Biological Chemistry. 275 (18): 13597–13604. doi:10.1074/jbc.275.18.13597. PMID 10788476.
  3. ↑ Sprague, J. (2006-01-01). "The Zebrafish Information Network: the zebrafish model organism database". Nucleic Acids Research. 34 (90001): D581–D585. doi:10.1093/nar/gkj086. ISSN 0305-1048. PMC 1347449. PMID 16381936.
  4. ↑ Lord, C.; Ferro-Novick, S.; Miller, E. A. (2013-02-01). "The Highly Conserved COPII Coat Complex Sorts Cargo from the Endoplasmic Reticulum and Targets It to the Golgi". Cold Spring Harbor Perspectives in Biology. 5 (2): a013367. doi:10.1101/cshperspect.a013367. ISSN 1943-0264. PMC 3552504. PMID 23378591.
  5. ↑ Barlowe, C (June 2003). "Signals for COPII-dependent export from the ER: what's the ticket out?". Trends in Cell Biology. 13 (6): 295–300. doi:10.1016/S0962-8924(03)00082-5. PMID 12791295.
  6. ↑ Jensen, Devon; Schekman, Randy (2011-01-01). "COPII-mediated vesicle formation at a glance". Journal of Cell Science. 124 (1): 1–4. doi:10.1242/jcs.069773. ISSN 1477-9137. PMID 21172817. S2CID 36908436.
  7. ↑ Gürkan, Cemal; Stagg, Scott M.; LaPointe, Paul; Balch, William E. (October 2006). "The COPII cage: unifying principles of vesicle coat assembly". Nature Reviews Molecular Cell Biology. 7 (10): 727–738. doi:10.1038/nrm2025. ISSN 1471-0072. PMID 16990852. S2CID 20469113.
  8. ↑ Bielli, Anna; Haney, Charles J.; Gabreski, Gavin; Watkins, Simon C.; Bannykh, Sergei I.; Aridor, Meir (2005-12-19). "Regulation of Sar1 NH2 terminus by GTP binding and hydrolysis promotes membrane deformation to control COPII vesicle fission". Journal of Cell Biology. 171 (6): 919–924. doi:10.1083/jcb.200509095. ISSN 1540-8140. PMC 2171319. PMID 16344311.
  9. ↑ Barlowe, Charles (August 2003). "Molecular Recognition of Cargo by the COPII Complex". Cell. 114 (4): 395–397. doi:10.1016/S0092-8674(03)00650-0. PMID 12941266. S2CID 13972413.
  10. ↑ Miller, Elizabeth A; Beilharz, Traude H; Malkus, Per N; Lee, Marcus C.S; Hamamoto, Susan; Orci, Lelio; Schekman, Randy (August 2003). "Multiple Cargo Binding Sites on the COPII Subunit Sec24p Ensure Capture of Diverse Membrane Proteins into Transport Vesicles". Cell. 114 (4): 497–509. doi:10.1016/S0092-8674(03)00609-3. PMID 12941277. S2CID 6247102.
  11. ↑ Stagg, Scott M.; Gürkan, Cemal; Fowler, Douglas M.; LaPointe, Paul; Foss, Ted R.; Potter, Clinton S.; Carragher, Bridget; Balch, William E. (2006-01-12). "Structure of the Sec13/31 COPII coat cage". Nature. 439 (7073): 234–238. Bibcode:2006Natur.439..234S. doi:10.1038/nature04339. ISSN 0028-0836. PMID 16407955. S2CID 2426465.
  12. ↑ Fath, Stephan; Mancias, Joseph D.; Bi, Xiping; Goldberg, Jonathan (June 2007). "Structure and Organization of Coat Proteins in the COPII Cage". Cell. 129 (7): 1325–1336. doi:10.1016/j.cell.2007.05.036. PMID 17604721. S2CID 10692166.
  13. ↑ Antonny, Bruno; Madden, David; Hamamoto, Susan; Orci, Lelio; Schekman, Randy (June 2001). "Dynamics of the COPII coat with GTP and stable analogues". Nature Cell Biology. 3 (6): 531–537. doi:10.1038/35078500. ISSN 1465-7392. PMID 11389436. S2CID 19851244.
  14. ↑ Zanetti, Giulia; Pahuja, Kanika Bajaj; Studer, Sean; Shim, Soomin; Schekman, Randy (January 2012). "COPII and the regulation of protein sorting in mammals". Nature Cell Biology. 14 (1): 20–28. doi:10.1038/ncb2390. ISSN 1465-7392. PMID 22193160. S2CID 2828521.
  15. ↑ Khoriaty, Rami; Vasievich, Matthew P.; Ginsburg, David (2012-07-05). "The COPII pathway and hematologic disease". Blood. 120 (1): 31–38. doi:10.1182/blood-2012-01-292086. ISSN 0006-4971. PMC 3390960. PMID 22586181.
  16. ↑ Skop, Ahna R.; Liu, Hongbin; Yates, John; Meyer, Barbara J.; Heald, Rebecca (2004-07-02). "Dissection of the Mammalian Midbody Proteome Reveals Conserved Cytokinesis Mechanisms". Science. 305 (5680): 61–66. Bibcode:2004Sci...305...61S. doi:10.1126/science.1097931. ISSN 0036-8075. PMC 3679889. PMID 15166316.
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