tetrasomy 12p

Pallister-Killian syndrome is a dysmorphic condition caused by mosaicism for tetrasomy of 12p.

Synopsis

 dysmorphism

• prominent forehead
• coarse facial features over time
• full cheeks
• long philtrum
• micrognathia

 auditory anomalies (deafness)

• large ears
• protruding lobules
• external auditory canal stenosis

 ocular anomalies

• sparse eyebrows
• sparse eyelashes
• upslanting palpebral fissures
• hypertelorism
• ptosis
• strabismus
• epicanthal folds
• cataracts
• exophthalmos

 nasal anomalies

• flat, broad nasal root
• short nose
• anteverted nostrils

 bucaal anomalies

• thin upper lip
• ’cupid-bow’ lip
• protruding lower lip
• macroglossia
• prominent lateral palatine ridges
• cleft palate
• bifid uvula

 dental anomalies

• delayed dental eruption

 Neck

• short neck
• webbed neck

 cardiac anomalies

• pericardial agenesis
• aortic stenosis
• patent ductus arteriosus
• septal defects
• hypertrophic cardiomyopathy

 pulmonary hypoplasia
 accessory nipples
 diaphragmatic hernia
 umbilical hernia
 omphalocele

 digestive anomalies

• intestinal malrotation
• imperforate anus
• anal atresia
• anal stenosis
• anteriorly placed anus

 genital anomalies

• persistence of urogenital sinus/cloaca
• inguinal hernia
• small scrotum
• hypospadias
• hypoplasia of labia majora
• cryptorchidism
• absent upper vagina
• absent uterus

 renal anomalies

• cystic kidneys
• renal dysplasia (dysplastic kidneys)

 skeletal anomalies and limb anomalies

• kyphoscoliosis
• sacral appendage
• congenital hip dislocation
• hypermobile joints
• mesomelic/rhizomelic limb shortening
• broad hands
• fifth finger clinodactyly
• short fingers
• distal digital hypoplasia
• postaxial polydactyly
• transverse palmar creases
• broad feet
• postaxial polydactyly
• short toes

 cutaneous anomalies

• hypopigmented streaks
• hyperpigmented streaks
• transverse palmar creases
• sparse anterior scalp hair
• sparse eyebrows
• sparse eyelashes

 cerebral anomalies

• profound mental retardation
• seizures
• hypotonia (newborn)
• hypertonia (older children and adolescents)
• contractures (older children and adolescents)

Etiology

 mosaic tetrasomy 12p in skin fibroblasts
 isochromosome often missing in lymphocyte

References