Dr F.Mojahedi,Pediatrician Mashhad Medical Genetic Counseling Center Craniosynostosis Premature closure of cranial sutures Birth prevalence 1/3000 Dr F.Mojahedi,Pediatrician Mashhad Medical Genetic Counseling Center ACECR

Normal skull

Double –Suture Synostosis Bicoronal synostosis (24m) Brachycephaly : with reduced A-P length of skull and increased height

Bicoronal Synostosis Acrocephaly:Skull height greater anteriorly,slanting downward posteriorly Oxycephaly (Turribrachycephally):Taller skull,shortened in both width&AP dimention

Complex multi sutures synostosis Skull is shaped like a cloverleaf (kleeblattschadel)

Syndromic CS FGFR related craniosynostosis(8) Others are considered in differential diagnosis Chotzen ,Boston- type CS,Antly- bixler,Baller- Gerold,Carpenter Greig cephalopolysyndactyly,Opitz c syndrome,Shprintzen- Goldberg ,Philadelphia- type CS Over 150 genetic disorders have known that CS is a part of them

FGFs/FGFRs

FGFs/FGFRs

FGFs/FGFRs

FGFs/FGFRs 8p11.2-p11.1 10q26 4p16.3

Apert Syndrome Craniofacial:Turribrachycephaly ,brachycephaly, acrocephaaly,4% cloverleaf moderate to sever midface hypoplasia Hands& Feet : Soft tissue ± Bone syndactyly Thumbs &great toes: mitten hand,socked feet Fused cervical vertebrae usually in C5-C6 ( 68%) , elbow ankylosis, rhizomelic shortening Occasional internal organ anomalies (CHD “ Ps”& genito urinary tract abnormalities “%10”) GUT:hydronephrosis,PCKD,Bicornuate uterus,vagina atresia,Cryptorchidism

Apert syndrome 1/ 65000-100000 Cleft palate “43%” UA:Coanal Atresia & reduced nasopharyngeal dimensions→obstructive sleep apnea→cor pulmonale LA:Complete or partial cartilage sleeve abnormality of the trachea RS”1.5%”:TEF,pulmonary aplasia “RML”

APERT SYNDROME Intellect: varying degree of DD and ID (vast majority) IQ(10-114 ,moderately 62-74) Common CNS malformation: CCA,Gray matter heterotopia,Encephalocele,Gyral abnormalities,Hypoplastic cerebral white matter,variable ventriculomegaly and…papilledema &optic atrophy with loss of vision in cases with insidious intracranial pressure increase Hydrocephaly (2%) ICP FGFR2 sequence alteration(Ser 252 Trp or Pro 253 Arg)

Molecular Genetic Evaluation Testing Strategy  An algorithm to increase efficiency and cost-effectiveness of molecular testing in craniosynostosis disorders involves initial performance of targeted mutation analysis for recurrent mutations as listed below, followed by selective gene sequencing Apert syndrome: Targeted mutation analysis of FGFR2 for the mutations p.Ser252Trp and p.Pro253Arg →If normal, sequence analysis for rare FGFR2 mutations or partial-gene insertions/deletions.

PHENOTYPE/GENOTYPE CORRELATION Cleft palate, severe ocular problems (strabismus, ptosis, astigmatism, and amblyopia), nasolacrimal stenosis, and possibly humeroradial synostosis are more common in individuals with the p.Ser252Trp pathogenic variant in FGFR2  [Akai et al 2006], whereas the degree of syndactyly and intellectual disability is more prominent in individuals with the p.Pro253Arg pathogenic variant in FGFR2  [Slaney et al 1996, Lajeunie et al 1999, Kanauchi et al 2003, Jadico et al 2006]. Individuals with Apert syndrome and the p.Pro253Arg pathogenic variant have a more improved craniofacial appearance following craniofacial surgery [von Gernet et al 2000].

Pfeiffer syndrome 2&3 1/100000 Craniofacial: Cloverleaf skull & extreme proptosis (often unable to close eyelids) in type 2 Turribrachycephalic skull shape in type 3 Thumbs &great toes:Broad & medially deviated great toes &broad thumbs Hands& Feet : Variable degree of brachydactyly, ankylosis of elbows, knees

Pfeiffer syndrome type 2 &3 Intellect: Developmental delay/intellectual disability common “Sever delay” Others: Choanal stenosis/atresia, laryngotracheal abnormalities, cleft palate; hydrocephalus; seizures; increased risk for early deat,Sacrococcygeal appendage in type2 Choanal stenosis/atresia, laryngotracheal abnormalities, hydrocephalus; increased risk for early deat in type3 FGFR 2 &1 related CS

Molecular Genetic Evaluation Testing Strategy  Pfeiffer syndrome:  Sequence analysis of exons 8 and 10 (in which approximately 80% of FGFR2 mutations are located). If normal, sequence analysis ofFGFR2 exons 3, 5, 11, 14, 15, 16, and 17 (in which an additional 10% of mutations are located) Consider FGFR1 testing for Pfeiffer syndrome(p.Pro252Arg.) if a mutation in FGFR2 is not identified and/or the patient has a milder phenotype.

GENOTYPE/PHENOTYPE CORRELATION Pfeiffer syndrome-causing variants p.Ser351Cys, p.Trp290Cys, and p.Cys342Arg in FGFR2 have been associated with severe phenotypes including: cloverleaf skull, severe exophthalmia, midface flattening, hydrocephalus requiring ventriculoperitoneal shunt, radio-ulnar-humeral synostosis, fusion of the cartilaginous tracheal rings (tracheal sleeve), congenital or acquired Chiari malformation, and frequently premature death [Zackai et al 2003, Hockstein et al 2004, Gonzales et al 2005, Akai et al 2006, Lajeunie et al 2006, Oliveira et al 2006, Stevens & Roeder 2006, Chen et al 2008, Ranger et al 2010].

Muenke 1/30000 Craniofacial:Variable, uni or bilateral coronal synostosis, Brachycephaly Turribrachycephaly macrocephaly* pansynostosis plagiocephally(facial asymmetry)* cloverleaf deformity or no sutures synostosis Mild to significant mid face hypoplasia,ocular hypertelorism.temporal bossing*,ptosis or proptosis(mild) Strabismus common(45%) Palatal abnormality

Muenke Thumbs :NL or broad great toes:+/- broad Hands& Feet :+/- carpal fusion or +/-tarsal fusion ,or cone shaped epiphyses,thimble-like middle phalanges Mild Brachydactyly Epilepsy(13%) low to mid frequency SNHL(33-100%)* In a large-cohort international study, more than 70% of individuals with Muenke syndrome had hearing loss, with a majority (70.8%) having bilateral sensorineural hearing loss the remainder having conductive (22%) and mixed forms (8.6%).

MUENKE Intellect: Developmental delay and/or intellectual disability, usually mild, has been reported in approximately one third of individuals [Muenke et al 1997, Kress et al 2006]. Compared to normative populations, individuals with Muenke syndrome have also been reported to be at increased risk for developing some behavioral and emotional problems [Maliepaard et al 2014, Yarnell et al 2015] A study of syndromic craniosynostosis by Bannink et al [2011] found behavioral problems to be more common in boys with Apert and Muenke syndromes, with a prevalence of 67% and 50%, respectively.ly

MUENKE *One of the four with Muenke syndrome had moderate intellectual disability (IQ <70) and a history of behavioral problems; *Two had borderline intellectual disability (IQ 70-80) and required special education; *One was of average intelligence (IQ 90-110), completed high school without difficulty, , Flapper et al [2009]  In a large international study of Muenke syndrome, 40.8% were reported to have intellectual disability and 66.3% had developmental delay, with speech delay the most common type (61.1%) [Kruszka et al 2016]. Approximately 24% had a diagnosis of ADHD.

MUENKE Intracranial anomalies: The following have been reported: Hippocampus and bilateral medial temporal dysgenesis in one person [Grosso et al 2003], who was described as developmentally normal Bilateral lateral ventricular dilatation and a small cerebellum in one person [Yu et al 2010] Porencephalic cyst of the occipital horn of left ventricle and absence of the corpus callosum in one person [Escobar et al 2009]

Testing Strategy Molecular genetic testing approaches can include single-gene testing or use of a multi-gene panel: Single-gene testing: Targeted mutation analysis{FGFR3 mutation(Pro250Arg)} Detection Mutation Rate:>99%  Note: Targeted analysis for the c.749C>G pathogenic variant in FGFR3 is rarely performed because the clinical features of Muenke syndrome overlap with those of other craniosynostosis conditions caused by different heterozygous pathogenic variants in FGFR3 and other craniosynostosis-related genes

SCS

SCS

SCS

SCS

TWIST1 is the only gene in which mutations are known to cause SCS.

Characterization of bHLH Family Proteins Two distinct regions: Basic Region HLH Region involved in DNA binding functions as a dimerization domain

bHLH

Saethre-Chotzen syndrome 1/25000-1/50000 Craniofacial:Bi or uni-coronal synostosis,acro or Brachycephally,other sutures synostosis or no synostosis at all Facial findings:ptosis,small ears with a prominent Crus,Low frontal hairline, strabismus, Downward slanting palpebral fissure Hands &feet:Hallux valgus,partial duplication of the first halluces, syndactyly”2-3”, mild brachydactyly,single palmar flexion crease, triangular epiphyses of the hallux Inceased ICP(21%) Tear duct stenosis Less common: Vertebral malformations ,SS,Palatal anomalies Conductive, mixed, and profound sensorineural hearing loss maxillary hypoplasia, ocular hypertelorism ID common with microdeletion7p21 ID(5 vs 35% in comparison to muenke syndrome)

Molecular Genetic Evaluation Testing Strategy To confirm/establish the diagnosis in a proband. Molecular genetic testing of TWIST1 by sequence analysis (>50%) → if no mutation is identified, perform deletion/duplication analysis (11-28%) →If no TWIST1 mutation can be identified by sequence analysis and deletion/duplication analysis  other disorders such as Muenke syndrome, caused by the p.Pro250Arg mutation in FGFR3 have been excluded  →If no mutation is identified or if the phenotype and/or family history suggest a complex chromosome abnormality, consider cytogenetic/FISH analysis(3.6%)

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