Pallister Hall syndrome
What are the symptoms?
The condition is very variable - individuals with mild PHS may only have one extra digit; more severe PHS is manifest by severe birth defects that can be lethal. The main features of PHS include:
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Hypothalamic hamartoma
, previously called hamartoblastoma. This is a benign brain tumour that arises from the hypothalamus (a region of the brain). Its presence can sometimes cause hormonal disturbance (see below). It is usually picked up on an MRI scan (neither cranial CT nor ultrasound scanning is adequate in looking for this tumour). No treatment is usually necessary and the hamartoma should not in most circumstances be removed or biopsied because of the risk of surgical complications.
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Pituitary gland abnormalities. The pituitary gland sits below the hypothalamus (see above). It is sometimes called "the master gland" in that it produces a number of hormones that control different metabolic and growth functions in the body. In PHS there may be a spectrum of abnormalities: at the mildest end the pituitary gland is located in the wrong place but works normally; at the more severe end of the spectrum the pituitary gland does not produce any hormones. Any baby with PHS needs urgent assessment by a paediatric endocrinologist (a doctor who specialises in looking after children with hormone problems) as they may need hormone replacement. Long-term endocrinology follow-up is necessary to monitor for hormone deficiency and to look for signs of precocious puberty.
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Polydactyly (extra fingers and/or toes). In PHS the extra digits typically arise between the second to fifth digits or at the outside edge of the fifth digit (called central and post-axial polydactyly respectively). Occasionally there may be some webbing between the digits (called syndactyly). A referral to an appropriate surgical team may be necessary.
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Dysplastic nails (small or unusual growing nails).
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Bifid Epiglottis. The epiglottis is a leaflet of tissue at the back of the throat that helps prevent food going down the windpipe. In PHS there is a cleft (split or opening) in the epiglottis but in general it does not cause problems. If the affected person's history suggests aspiration of food or breathing problems then an ENT opinion should be sought. It is an important feature in making a diagnosis of PHS, as it appears to be rare in other conditions.
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Imperforate Anus. This means the back passage has not opened during development and results in a newborn baby being unable to pass stool. It requires surgery soon after birth.
Other features may include congenital heart defects, renal and genitourinary abnormalities and seizures. A small number of children will have learning difficulties. The long-term outcome for affected individuals depends on the presence or absence of life-threatening malformations (such as the presence of hormone deficiencies) but, if mildly affected, is good.
Background
| Inheritance patterns and prenatal diagnosis 
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