Syndromes: skeletal & sex Flashcards
What kind of shortening is rhizomelic
Proximal
Spondyloepiphyseal dysplasia, early arthritis, retinal detachment, myopia, cataract, hearing loss, Robin sequence
Stickler syndrome: AD, COL2, COL9, COL11 (abnormal structural collagen)
Knee/hip pain in childhood, need large joint replacement in 30s. Short for family, ragged growth plates on XR.
Multiple epiphyseal dysplasia: AD, COL9, COMP, MATN3 (abnormal structural collagen)
Limb shortening, hitchhiker’s thumb, boxer/cauliflower ears, spinal deformity, early OA, joint contractures
Diastrophic dysplasia: AR, SLC26A2 (IEM of cartilage/sulfate metabolism)
Short fingers, nasomaxillary hypoplasia, stippled epiphyses; mild/minimal
Chondrodysplasia punctata: XL, ARSE (IEM of cartilage metabolism)
Rhizomelic short stature, macrocephaly, midface hypoplasia, frontal bossing, trident hands, genu varum (bow legs), joint hyperextensibility
Achondroplasia: AD GOF of FGFR3, limits cartilage formation/ossification
Complications of achondroplasia in infancy
Hydrocephalus, hypotonia, motor delay, poor drainage of Eustachian tubes, OSA from large adenoid/tonsils & midface hypoplasia + central apnea from foramen magnum narrowing –> 7.5% mortality of apnea
Complications of achondroplasia in childhood/adulthood
Craniocervical junction compression, obesity, back pain (exaggerated lumbar lordosis), spinal stenosis, dental crowding, cardiovascular disease (interestingly no T2DM or arthritis).
Cloverleaf skull, micromelia, short limbs, usually fatal from lung underdevelopment
Thanatophoric dysplasia: AD GOF in FGFR3 (p.Lys650Glu)
Bowed long bones, narrow iliac wings, Robin sequence, pulmonary hypoplasia, 2/3 of male w/ambiguous genitalia
Campomelic dysplasia: AD, SOX9
Variant for achondroplasia vs hypochondroplasia
m.1138G>A, p.Gly380Arg // m.1620C>A or G, p.Asn540Lys
Cataracts, coronal defects of vertebrae, rhizomelia, chondrodysplasia punctata
Rhizomelic chondrodysplasia punctata types 1-3: AR PEXY7, GNPAT, AGPS (peroxisomal)
Rhizomelia, coronal clefts of vertebral bodies, cataracts, male lethal
Chondrodysplasia punctata type 2 aka Conradi-Hunerman syndrome: XD, CDPX2 (peroxisomal/cholesterol synthesis)
Short forearm w/Madelung deformity (curved radius w/step-off at wrist), limited mobility, tibiofibular shortening, short stature. Usually female > male but only short stature w/Turner syndrome…
Leri Weill dysostosis: haploinsufficiency for SHOX or SHOXY, usually with X-chromosome deletion
Aplasia/severe hypoplasia of ulna and fibula, thickened/curved radius and tibia, hypoplasia of mandible
Langer Mesomelic Dysplasia: total KO of SHOX or SHOXY. Very rare.
Absent ossification of lateral parts of clavicles, wide fontanelles and sagittal suture, low bone density.
Cleidocranial dysplasia: Runx2/CBFA1 (osteoblast)
Benign cartilage-capped tumors (osteochondromas); stop forming once growth plate closed, malignant transformation ~1%/year
Hereditary multiple exostoses: AD, EXT1 or EXT2
Osteochondromas + enchondromas
Metachrondromatosis: AD, PTPN11
Fibrous dysplasia of bone (one or many bones), bone pain, pathologic fracture
Somatic mutations in GNAS1
Cafe-au-lait spots w/jagged coastal borders, hyperfunctional endocrine disorders (precocious puberty, hyperthyroidism, excess GH, Cushing syndrome), fibrous dysplasia of bone
McCune-Albright Syndrome: somatic mutations in GNAS1
Multiple fractures, blue sclerae
Osteogenesis imperfecta: AD COL1A1 and 1A2, many AR forms
Osteosclerosis of whole skeleton within months, macrocephaly, frontal bossing, craniosynostosis, hypodontia/malformed teeth +/- hydrocephalus, CN compression (blind/deaf).
Neuronopathic form with seizures, DD, degeneration of retinal/CNS.
Osteopetrosis, caused by defects in mechanisms for osteoclast acidification and digestion of bone.
Infantile malignant: AR TCIRG1, CLCN7 (Cl channel), OSTM1 (neuropathic form)
Short limbs, short stature, obtuse mandibular angle w/convex nasal ridge, osteosclerosis w/bone fragility, delayed closure of cranial sutures, clavicular dysplasia
Pycnodysostosis: AR, CTSK (cathepepsin K)
Later osteopetrosis presentations genes
Intermediate: CLCN7, PLECKHM1, TNFS11 (RANKL)
Late-onset: CLCN7, LRP5
With RTA: AR CA2 (carbonic anhydrase)
Tx of osteopetrosis
Bone marrow transplant to replace osteoclasts (not for neuronopathic form, often OSTM1)
Sertoli vs Leydig cells
Sertoli: spermatogenesis, secrete Mullerian inhibiting factor locally
Leydig: hCG receptors, secrete testosterone locally for Wolffian ducts, external genitalia
Needed for testicular development
SRY
Needed for male external genitalia development
5a reductase changing testosterone -> circulating DHT until puberty
Syndromes associated with ambiguous genitalia w/dysmorphic features
SLO, campomelic dysplasia, mixed gonadal dysgenesis
46,XY with ambiguous genitalia
Androgen insensitivity
5-alpha reductase deficiency
DAX1 duplication
SF1
Normal or dysgenic testis + streak gonad, external genitalia variable, may have short webbed neck, low-set ears, short stature, edematous hands/feet
Mixed gonadal dysgenesis: mosaic 45X/46XY
DD, ambiguous genitalia, 2-3 toe syndactyly
Smith-Lemli-Opitz: 7-dehydrocholesterol reductase deficiency (low testosterone)
Streak gonads, nephrotic syndrome, 46XY with female organs, no testosterone
Frasier syndrome: WT1 splice site mutations
Male w/ambiguous genitalia, Wilms tumor, congenital nephropathy
Denys-Drash syndrome: WT1 missense
Adrenal insufficiency and 46,XY with sex reversal
SF1 - transcription factor that affects MIF amongst other genes
Congenital adrenal hypoplasia, hypogonadotrophic hypogonadism, don’t go through puberty (due to decreased gonad, adrenal, and pituitary development)
DAX1 loss of function; can have Xp21 continuous gene deletion syndrome w/Duchenne muscular dystrophy, glycerol kinase deficiency with DD. (Note DAX1 duplication has ambiguous genitalia)
46XY with female external genitalia but no ovaries/uterus, +testicles w/high circulating androgens
Androgen insensitivity, XR
Complete - totally female in appearance
Partial - some masculinization/ambiguous genitalia
46XY with ambiguous external genitalia that virilize at puberty, normal internal male structures
5-alpha reductase deficiency, AR
46XX with virilized external genitalia, decreased cortisol +/- salt wasting (decreased aldosterone)
Congenital adrenal hyperplasia (blockade in steroid synthesis -> androgen excess): AR 21-hydroxylase deficiency; if LOF with deletion/nonsense/recombination with pseudogene –> salt wasting.
Presence of both mature ovarian and testicular tissue (45% w/ovotestis), usually ambiguous genitalia but may be normal
Ovotesticular DSD (true hermaphrodism): etiology unknown, some 46XX+SRY, 1/3 mosaic XX/XY
Anogenital ratio
Anus-posterior fourchette / anus-base of clitoris, if >0.5 likely virilized
Which percursor is elevated with 21-hydroxylase deficiency?
17-hydroxyprogesterone
Skin hyperextensibility + joint hypermobility; minor criteria w/bruising, soft skin, atrophic scars/delayed wound healing, hernias
Classical EDS: AD, COL5A1, COL5A2, rarely COL1A1; “Classical-like” AR TNXB, ACLP w/cardiac findings
Acrogeria (aged appearance), spontaneous rupture of arteries, intestines, uterus
Vascular EDS: AD (50% de novo), COL3A1.
Joint laxity, hypotonia, scleral fragility, marfanoid w/ progressive kyphoscoliosis
Kyphoscoliotic EDS: AR, PLOD1 (lysyl hydroxylase, modifies collagen), FKBP14 (+ hearing loss & vascular rupture)
Skeletal dysplasia, hypermobile joints, blue sclerae + some with progeroid appearance
Spondylodysplastic EDS: AR, B4GALT7, B3GALT6, SCL39A13 (Zn transporter). Very rare.
Extreme multiple joint laxity w/difficulty weight bearing, congenital hip dislocation, fractures, scoliosis, short, hyperextensible skin
Arthrochalasia EDS: AD, COL1A1, COL1A2 (usually loss of exon 6, loss of cleavage site)
Sagging skin, hernias, blue sclerae, short stature, short fingers, joints lax but don’t sublux, risk of organ rupture
Dermatosparaxis EDS: AR, ADAMTS2 (peptidase). Very rare
High trypase, EDS symptoms + systemic venom reaction, flushing/pruritis, urticaria, anaphylaxis, retained primary teeth
Hereditary Alpha Tryptasemia: duplication or triplication of TPSAB1. Treat with omulizumab.
Aortic aneurysms, arterial tortuosity, dissections, bifid uvula, cleft palate, hyperteloric, C-spine instability
Loeys-Dietz: AD, TGFBR 1/2, SMAD 2/3, TGFB 2/3
Marfan diagnostic criteria
1) Aortic aneurysm + ectopia lentis
2) Aortic aneurysm + FBN1 variant
3) Aortic aneurysm + systemic score ≥7
4) Family history + ectopic lentis OR systemic score
5) Family history + aortic aneurysm
Marfan systemic signs (≥7/20 points needed)
Wrist/thumb sign, pectus, hind foot deformity, pes planus, PTX, dural ectasia, protrusio acetabulum, decreased upper:lower segment, increased arm span, scoliosis, reduced elbow extension, facial features, skin striae, myopia, MVP
Contractures, joint laxity, arachnodactyly, pulmonary emphysema, aortic dilatation w/valvular dysplasia, early death
Neonatal Marfan, due to variants in axons 24-27, 31-32 of FBN1
Marfan appearance without ectopic lentis, congenital contractions, severe aortic dilatation w/o dissection, crumpled ears
Congenital contractural arachnodactyly: AD, FBN2
Craniosynostosis, hypotonia, marfanoid features incl aortic dilatation, no arterial tortuosity, LD/ID
Spritzen Goldberg Syndrome: AD, SKI
Dilatation of ascending aorta w/dissections, no other systemic findings of CTD.
TAAD: 20% genetic incl TGFBR 1/2, ACTA2, MYH11, SMAD3…rarely FBN1
What sutures prematurely fuse in trigonocephaly?
Metopic sutures
What sutures prematurely fuse in brachycephaly (short)?
Bilateral coronal sutures
What sutures prematurely fuse in scaphocephaly (narrow & long)?
Saggital sutures
What sutures prematurely fuse in turricephaly (tall & narrow)?
Coronal +/- lambdoid
Coronal synostosis or macrocephaly, high forehead, hypertelorism, midface hypoplasia, downturned PF, hearing loss, DD, carpal/tarsal fusions
Muenke syndrome: FGFR3 P250R
Rhizomelic shortening, midface hypoplasia, syndactyly, fused cerebral vertebrae, cleft palate, bifid uvula, abnormal corpus callosum and/or gyri, cognitive impairment
Apert syndrome: AD, FGFR2
Craniosynostosis (various sutures), proptosis w/shallow orbits, mandibular prognathism, C-spine abnormalities, normal intellect, risk of intracranial hypertension
Crouzon: AD, 50% sporadic. FGFR2, some overlap w/Pfeiffer
Variable: Mod midface hypoplasia –>cloverleaf skull or turribrachycephaly, broad thumbs/toes, syndactyly of hands.
Pfeiffer syndrome: FGFR1 (P252R), FGFR2 some overlap w/Crouzon
Craniosynostosis, ptosis, small ears, low frontal hairline, duplicated hallux, syndactyly; +/- ID
Saethre-Chotzen: AD, TWIST1 (TF)
Clover leaf skull, short stature, obesity, poly/syndactyly, low-set ears, down slanting PF, hypogonadism
Carpenter syndrome: AR, RAB23 (vesicle transport)
Craniosynostosis + radial defects
Baller Gerold syndrome: AR, RECQL (DNA helicase)
Craniosynostosis + urogenital anomalies, joint contractures, ambiguous genitalia
Antley-Bixler syndrome: CYP450 reductase
Trigonocephaly, microcephaly, up slanting eyes, macrostomia, short stature, CHD, polydactyly, transverse limb reductions, short limbs, hypotonia, seizures, DD, skin laxity
Optiz C syndrome: AD, CD96 (IG superfamily)
Craniosynostosis, developmental delay, marfanoid connective tissue, maxillary hypoplasia, ptosis
Shprintzen-Goldberg syndrome: AD, FBN1 or SKI
Craniosynostosis, hypertelorism, bifid nasal tip, grooved nails, wiry hair, thoracic abnormalities
Craniofrontonasal syndrome: XD, Ephrin B. Males just w/hypertelorism?