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Disease Profile

Pallister-Killian mosaic syndrome

Prevalence
Prevalence estimates on Rare Medical Network websites are calculated based on data available from numerous sources, including US and European government statistics, the NIH, Orphanet, and published epidemiologic studies. Rare disease population data is recognized to be highly variable, and based on a wide variety of source data and methodologies, so the prevalence data on this site should be assumed to be estimated and cannot be considered to be absolutely correct.

Unknown

Age of onset

Neonatal

ICD-10

Q99.8

Inheritance

Autosomal dominant A pathogenic variant in only one gene copy in each cell is sufficient to cause an autosomal dominant disease

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Autosomal recessive Pathogenic variants in both copies of each gene of the chromosome are needed to cause an autosomal recessive disease and observe the mutant phenotype

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X-linked
dominant X-linked dominant inheritance, sometimes referred to as X-linked dominance, is a mode of genetic inheritance by which a dominant gene is carried on the X chromosome.

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X-linked
recessive Pathogenic variants in both copies of a gene on the X chromosome cause an X-linked recessive disorder

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Mitochondrial or multigenic Mitochondrial genetic disorders can be caused by changes (mutations) in either the mitochondrial DNA or nuclear DNA that lead to dysfunction of the mitochondria and inadequate production of energy.

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Multigenic or multifactor Inheritance involving many factors, of which at least one is genetic but none is of overwhelming importance, as in the causation of a disease by multiple genetic and environmental factors.

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Not applicable

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Other names (AKA)

Chromosome 12, Isochromosome 12p syndrome; Killian syndrome; Killian Teschler-Nicola syndrome;

Categories

Chromosome Disorders; Congenital and Genetic Diseases; Digestive Diseases;

Summary

Pallister-Killian mosaic syndrome is a multi-system disorder that is characterized by extremely weak muscle tone (hypotonia) in infancy and early childhood, intellectual disability, distinctive facial features, sparse hair, areas of unusual skin coloring (pigmentation), and other birth defects. The signs and symptoms of Pallister-Killian mosaic syndrome can vary, although most documented cases of people with the syndrome have severe to profound intellectual disability and other serious health problems.[1]

Pallister-Killian mosaic syndrome is usually caused by the presence of an abnormal extra chromosome 12 called isochromosome 12p. An isochromosome is a chromosome with two identical arms. Normal chromosomes have one long (q) arm and one short (p) arm, but isochromosomes have either two q arms or two p arms. Isochromosome 12p is a version of chromosome 12 made up of two p arms. Cells normally have two copies of each chromosome, one inherited from each parent. In people with Pallister-Killian mosaic syndrome, cells have the two usual copies of chromosome 12, but some cells also have the isochromosome 12p. These cells have a total of four copies of all the genes on the p arm of chromosome 12. The extra genetic material from the isochromosome disrupts the normal course of development, causing the characteristic features of this disorder.[1]

Although Pallister-Killian mosaic syndrome is usually caused by an isochromosome 12p, other, more complex chromosomal changes involving chromosome 12 are responsible for the disorder in rare cases.[1]

Treatment depends upon the specific symptoms present in each individual. Treating medical and developmental problems early can help to optimize outcome.[2]

Symptoms

This table lists symptoms that people with this disease may have. For most diseases, symptoms will vary from person to person. People with the same disease may not have all the symptoms listed. This information comes from a database called the Human Phenotype Ontology (HPO) . The HPO collects information on symptoms that have been described in medical resources. The HPO is updated regularly. Use the HPO ID to access more in-depth information about a symptom.

Medical Terms Other Names
Learn More:
HPO ID
80%-99% of people have these symptoms
Cachexia
Wasting syndrome
0004326
Delayed eruption of teeth
Delayed eruption
Delayed teeth eruption
Delayed tooth eruption
Eruption, delayed
Late eruption of teeth
Late tooth eruption

[ more ]

0000684
Delayed skeletal maturation
Delayed bone maturation
Delayed skeletal development

[ more ]

0002750
Downturned corners of mouth
Downturned corners of the mouth
Downturned mouth

[ more ]

0002714
Everted lower lip vermilion
Drooping lower lip
Outward turned lower lip

[ more ]

0000232
Hypohidrosis
Decreased ability to sweat
Decreased sweating
Sweating, decreased

[ more ]

0000966
Intellectual disability, severe
Early and severe mental retardation
Mental retardation, severe
Severe mental retardation

[ more ]

0010864
Joint hyperflexibility
Joints move beyond expected range of motion
0005692
Long philtrum
0000343
Muscular hypotonia
Low or weak muscle tone
0001252
Ptosis
Drooping upper eyelid
0000508
Reduced tendon reflexes
0001315
Short neck
Decreased length of neck
0000470
Short stature
Decreased body height
Small stature

[ more ]

0004322
Sparse and thin eyebrow
Thin, sparse eyebrows
0000535
Sparse hair
0008070
Thick upper lip vermilion
Full upper lip
Increased volume of upper lip
Plump upper lip
Prominent upper lip
Thick upper lip

[ more ]

0000215
Thin upper lip vermilion
Thin upper lip
0000219
30%-79% of people have these symptoms
Anteverted nares
Nasal tip, upturned
Upturned nasal tip
Upturned nose
Upturned nostrils

[ more ]

0000463
Coarse facial features
Coarse facial appearance
0000280
Frontal bossing
0002007
Hypertelorism
Wide-set eyes
Widely spaced eyes

[ more ]

0000316
Prominent forehead
Pronounced forehead
Protruding forehead

[ more ]

0011220
Short nose
Decreased length of nose
Shortened nose

[ more ]

0003196
Telecanthus
Corners of eye widely separated
0000506
Upslanted palpebral fissure
Upward slanting of the opening between the eyelids
0000582
5%-29% of people have these symptoms
Abnormal soft palate morphology
0100736
Anal atresia
Absent anus
0002023
Strabismus
Cross-eyed
Squint
Squint eyes

[ more ]

0000486
Percent of people who have these symptoms is not available through HPO
Anal stenosis
Narrowing of anal opening
0002025
Anhidrosis
Lack of sweating
Sweating dysfunction

[ more ]

0000970
Anteriorly placed anus
0001545
Aortic valve stenosis
Narrowing of aortic valve
0001650
Aplasia of the upper vagina
Absent upper vagina
0012673
Aplasia of the uterus
Absent uterus
uterus absent

[ more ]

0000151
Atrial septal defect
An opening in the wall separating the top two chambers of the heart
Hole in heart wall separating two upper heart chambers

[ more ]

0001631
Bifid uvula
0000193
Broad foot
Broad feet
Wide foot

[ more ]

0001769
Broad palm
Broad hand
Broad hands
Wide palm

[ more ]

0001169
Cataract
Clouding of the lens of the eye
Cloudy lens

[ more ]

0000518
Clinodactyly of the 5th finger
Permanent curving of the pinkie finger
0004209
Coarctation of aorta
Narrowing of aorta
Narrowing of the aorta

[ more ]

0001680
Congenital diaphragmatic hernia
0000776
Congenital hip dislocation
Dislocated hip since birth
0001374
Cryptorchidism
Undescended testes
Undescended testis

[ more ]

0000028
Depressed nasal bridge
Depressed bridge of nose
Flat bridge of nose
Flat nasal bridge
Flat, nasal bridge
Flattened nasal bridge
Low nasal bridge
Low nasal root

[ more ]

0005280
Epicanthus
Eye folds
Prominent eye folds

[ more ]

0000286
Feeding difficulties
Feeding problems
Poor feeding

[ more ]

0011968
Flexion contracture
Flexed joint that cannot be straightened
0001371
Full cheeks
Apple cheeks
Big cheeks
Increased size of cheeks
Large cheeks

[ more ]

0000293
Generalized hypotonia
Decreased muscle tone
Low muscle tone

[ more ]

0001290
Hearing impairment
Deafness
Hearing defect

[ more ]

0000365
Hyperpigmented streaks
0007572
Hypertonia

Diagnosis

Making a diagnosis for a genetic or rare disease can often be challenging. Healthcare professionals typically look at a person’s medical history, symptoms, physical exam, and laboratory test results in order to make a diagnosis. The following resources provide information relating to diagnosis and testing for this condition. If you have questions about getting a diagnosis, you should contact a healthcare professional.

Testing Resources

  • Orphanet lists international laboratories offering diagnostic testing for this condition.

    Organizations

    Support and advocacy groups can help you connect with other patients and families, and they can provide valuable services. Many develop patient-centered information and are the driving force behind research for better treatments and possible cures. They can direct you to research, resources, and services. Many organizations also have experts who serve as medical advisors or provide lists of doctors/clinics. Visit the group’s website or contact them to learn about the services they offer. Inclusion on this list is not an endorsement by GARD.

    Organizations Supporting this Disease

      Learn more

      These resources provide more information about this condition or associated symptoms. The in-depth resources contain medical and scientific language that may be hard to understand. You may want to review these resources with a medical professional.

      Where to Start

      • Genetics Home Reference (GHR) contains information on Pallister-Killian mosaic syndrome. This website is maintained by the National Library of Medicine.
      • The National Organization for Rare Disorders (NORD) has a report for patients and families about this condition. NORD is a patient advocacy organization for individuals with rare diseases and the organizations that serve them.
      • Unique is a source of information and support for families and individuals affected by rare chromosome disorders. Click on the link to view information about Pallister-Killian mosaic syndrome.

        In-Depth Information

        • The Monarch Initiative brings together data about this condition from humans and other species to help physicians and biomedical researchers. Monarch’s tools are designed to make it easier to compare the signs and symptoms (phenotypes) of different diseases and discover common features. This initiative is a collaboration between several academic institutions across the world and is funded by the National Institutes of Health. Visit the website to explore the biology of this condition.
        • Online Mendelian Inheritance in Man (OMIM) is a catalog of human genes and genetic disorders. Each entry has a summary of related medical articles. It is meant for health care professionals and researchers. OMIM is maintained by Johns Hopkins University School of Medicine. 
        • Orphanet is a European reference portal for information on rare diseases and orphan drugs. Access to this database is free of charge.
        • PubMed is a searchable database of medical literature and lists journal articles that discuss Pallister-Killian mosaic syndrome. Click on the link to view a sample search on this topic.

          References

          1. Pallister-Killian mosaic syndrome. Genetics Home Reference. June 2016; https://ghr.nlm.nih.gov/condition/pallister-killian-mosaic-syndrome.
          2. Dr. Ian Krantz. Recommended Clinical Evaluations for the Child with PKS. PKS Kids. 2015; https://www.pkskids.net/PKSClinicalRecomendations2012-08.pdf.

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