Variability of systemic and oro-dental phenotype in two families with non-lethal Raine syndrome with FAM20C mutations.
BACKGROUND
Raine syndrome (RS) is a rare autosomal recessive bone dysplasia typified by osteosclerosis and dysmorphic facies due to FAM20C mutations. Initially reported as lethal in infancy, survival is possible into adulthood. We describe the molecular analysis and clinical phenotypes of five individuals from two consanguineous Brazilian families with attenuated Raine Syndrome with previously unreported features.


METHODS
The medical and dental clinical records were reviewed. Extracted deciduous and permanent teeth as well as oral soft tissues were analysed. Whole exome sequencing was undertaken and FAM20C cDNA sequenced in family 1.


RESULTS
Family 1 included 3 siblings with hypoplastic Amelogenesis Imperfecta (AI) (inherited abnormal dental enamel formation). Mild facial dysmorphism was noted in the absence of other obvious skeletal or growth abnormalities. A mild hypophosphataemia and soft tissue ectopic mineralization were present. A homozygous FAM20C donor splice site mutation (c.784 + 5 g > c) was identified which led to abnormal cDNA sequence. Family 2 included 2 siblings with hypoplastic AI and tooth dentine abnormalities as part of a more obvious syndrome with facial dysmorphism. There was hypophosphataemia, soft tissue ectopic mineralization, but no osteosclerosis. A homozygous missense mutation in FAM20C (c.1487C > T; p.P496L) was identified.


CONCLUSIONS
The clinical phenotype of non-lethal Raine Syndrome is more variable, including between affected siblings, than previously described and an adverse impact on bone growth and health may not be a prominent feature. By contrast, a profound failure of dental enamel formation leading to a distinctive hypoplastic AI in all teeth should alert clinicians to the possibility of FAM20C mutations.
Oral Care Center for Inherited Diseases, University Hospital of Brasilia, Department of Dentistry, Health Sciences School, University of Brasilia, Brasilia, Brazil. acevpoppe@gmail.com.
Ana Carolina
AC
Acevedo
Section of Ophthalmology and Neuroscience, University of Leeds, Leeds, UK. j.a.poulter@leeds.ac.uk.
James A
JA
Poulter
Oral Care Center for Inherited Diseases, University Hospital of Brasilia, Department of Dentistry, Health Sciences School, University of Brasilia, Brasilia, Brazil. priscila.gomes.alves@gmail.com.
Priscila Gomes
PG
Alves
Oral Care Center for Inherited Diseases, University Hospital of Brasilia, Department of Dentistry, Health Sciences School, University of Brasilia, Brasilia, Brazil. carollourenco@yahoo.com.br.
Caroline Lourenço
CL
de Lima
Department of Pediatrics, School of Medicine, University of Brasilia, Brasilia, Brazil. lc-castro@uol.com.br.
Luiz Claudio
LC
Castro
Oral Care Center for Inherited Diseases, University Hospital of Brasilia, Department of Dentistry, Health Sciences School, University of Brasilia, Brasilia, Brazil. paulomarcioyamaguti@gmail.com.
Paulo Marcio
PM
Yamaguti
Oral Care Center for Inherited Diseases, University Hospital of Brasilia, Department of Dentistry, Health Sciences School, University of Brasilia, Brasilia, Brazil. lilianmpaula@gmail.com.
Lilian M
LM
Paula
Section of Genetics, School of Medicine, University of Leeds, Leeds, UK. d.a.parry@leeds.ac.uk.
David A
DA
Parry
Section of Ophthalmology and Neuroscience, University of Leeds, Leeds, UK. c.logan@leeds.ac.uk.
Clare V
CV
Logan
Section of Ophthalmology and Neuroscience, University of Leeds, Leeds, UK. c.e.l.smith@leeds.ac.uk.
Claire E L
CE
Smith
Section of Ophthalmology and Neuroscience, University of Leeds, Leeds, UK. medcaj@leeds.ac.uk.
Colin A
CA
Johnson
Section of Ophthalmology and Neuroscience, University of Leeds, Leeds, UK. c.inglehearn@leeds.ac.uk.
Chris F
CF
Inglehearn
Section of Ophthalmology and Neuroscience, University of Leeds, Leeds, UK. a.j.mighell@leeds.ac.uk.|Department of Oral Medicine, School of Dentistry, University of Leeds, Leeds, UK. a.j.mighell@leeds.ac.uk.
Alan J
AJ
Mighell
D000015:Abnormalities, Multiple / Q000235:genetics*; D000293:Adolescent; D001483:Base Sequence; D047389:Casein Kinase I / Q000235:genetics*; D002648:Child; D002675:Child, Preschool; D002972:Cleft Palate / Q000150:complications / Q000235:genetics*; D005094:Exophthalmos / Q000150:complications / Q000235:genetics*; D016326:Extracellular Matrix Proteins / Q000235:genetics*; D005260:Female; D006801:Humans; D008297:Male; D008831:Microcephaly / Q000150:complications / Q000235:genetics*; D009056:Mouth Abnormalities / Q000150:complications*; D009154:Mutation; D010026:Osteosclerosis / Q000150:complications / Q000235:genetics*; D010375:Pedigree; D010641:Phenotype; D014071:Tooth Abnormalities / Q000150:complications*; D055815:Young Adult
D016326:Extracellular Matrix Proteins; D047389:Casein Kinase I; C524449:FAM20C protein, human