omphalocele

3MC Syndromes

Clinical Characteristics
Ocular Features: 

The major ocular features involve the periocular structures.  These result in the typical facial dysmorphism and include hypertelorism, blepharoptosis, blepharophimosis, and highly arched eyebrows. Ptosis, unilateral or bilateral, can be present.

One patient was reported to have unilateral aniridia and a corneal leucoma.  Tear duct atresia was reported in another individual.

Systemic Features: 

Systemic features are highly variable in their presence and severity.   Facial clefting, growth deficiency, cognitive impairment, and hearing loss are present about half the time in some combination while craniosynostosis, urogenital anomalies, and radioulnar synostosis are seen in about a third of individuals.  More rare features include cardiac defects and abdominal midline defects (omphalocele and diastasis recti).

Genetics

This condition (3MC) is now postulated to include at least 3 disorders (Malpuech-Michels-Mingarelli-Carnevale syndromes) and considered here as a single autosomal recessive disease complex with overlapping clinical features that requires genotyping for diagnostic separation.  These are: 3MC1 syndrome (257920) resulting from homozygous mutations in the MASP1 gene (3q27.3), 3MC2 syndrome (265050) caused by mutations in the COLEC11 gene (2p25.3) and 3MC3 (248340) with mutations in the COLEC10 gene (8q24.12).

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

No effective general treatment has been reported.

References
Article Title: 

COLEC10 is mutated in 3MC patients and regulates early craniofacial development

Munye MM, Diaz-Font A, Ocaka L, Henriksen ML, Lees M, Brady A, Jenkins D, Morton J, Hansen SW, Bacchelli C, Beales PL, Hernandez-Hernandez V. COLEC10 is mutated in 3MC patients and regulates early craniofacial development. PLoS Genet. 2017 Mar 16;13(3):e1006679. doi: 10.1371/journal.pgen.1006679. eCollection 2017 Mar.

PubMed ID: 
28301481

Mutations in lectin complement pathway genes COLEC11 and MASP1 cause 3MC syndrome

Rooryck C, Diaz-Font A, Osborn DP, Chabchoub E, Hernandez-Hernandez V, Shamseldin H, Kenny J, Waters A, Jenkins D, Kaissi AA, Leal GF, Dallapiccola B, Carnevale F, Bitner-Glindzicz M, Lees M, Hennekam R, Stanier P, Burns AJ, Peeters H, Alkuraya FS, Beales PL. Mutations in lectin complement pathway genes COLEC11 and MASP1 cause 3MC syndrome. Nat Genet. 2011 Mar;43(3):197-203.

PubMed ID: 
21258343

Donnai-Barrow Syndrome

Clinical Characteristics
Ocular Features: 

A number of ocular features have been described in this disorder, including telecanthus, hypertelorism, and iris hypoplasia with marked iris transillumination.  Myopia is commonly present and retinal detachments are a risk.  Several patients had iris colobomas.  Cataracts, small optic nerves, and macular hypoplasia have been reported as well.  The lid fissures usually slant downward. 

Systemic Features: 

The facial dysmorphology, in addition to the periocular malformations, includes a prominent brow or frontal bossing, posterior rotation of the ears, a flat nasal bridge and a short nose.  Sensorineural hearing loss is universal and at least some patients have complete or partial agenesis of the corpus callosum, and an enlarged anterior fontanel.  Diaphragmatic and umbilical hernias often occur together.  Low-molecular-weight proteinuria in the absence of aminoaciduria is a frequent feature.  Developmental delays are often seen but occasional patients have normal intellect.  Rare patients have seizures. 

Genetics

This is a rare autosomal recessive disorder caused by homozygous mutations in the LRP2 (low-density lipoprotein receptor-related protein 2 or megalin) gene located at 2q24-q31.  Some patients have an ocular phenotype resembling the Stickler syndrome (609508).

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

Treatment is focused on specific manifestations such as cataract and retinal detachment surgery. Patients need to be monitored throughout life for retinal disease.  Omphaloceles and diaphragmatic hernias need to be repaired.  Hearing aids may be beneficial. 

References
Article Title: 
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