Autosomal dominant, PTEN gene (10q23). See OMIM.
Clinically –
In some cases intestinal polyps, papilloedema, immunodeficiency.
Lipid transfer protein. One of the allergen families. Cross reactions therefore seen with fruit (stoned fruit but also raspberry), nuts, seeds (eg linseed/flaxseed), pulses, even cereals, tomatoes, vegetables (lettuce! Cabbage!). You may also see reactions only to composite foods eg pizza, curry, due to multiple allergens being present, but only producing reaction due to co-factors.
A less common cause of Pollen food syndrome than PR10 allergy. Thought of as a Mediterranean thing but increasing reports from Northern and Western Europe. Plane tree and mugwort have LTP but not thought to be the usual cause for sensitisation (except maybe in China). In N/W Europe, often birch sensitised too but not to be confused with PR10 type PFS!
Important to identify because heat stable (so not affected by heat, processing, digestion etc in the way PR10 allergens are) and potential for severe reactions.
So do component testing if atypical (eg unusually severe) reactions to fruit.
LTP allergy also seems to be more likely to cause reactions of varying severity, compared with primary food allergy, with co-factors perhaps more important. Eating multiple different plant foods at the same time seems to be the most likely cause of co-factor associated severe reactions. Of course, co-factors can co-exist too (alcohol and dancing, for example). So some would advise:
Danger that with LTP allergy you show sensitisation to multiple foods, and then you end up on a restricted diet without knowing whether there is allergy or not.
Peach allergen Pru p 3 is a good surrogate for LTP allergy, even if peach hasn’t been a problem! If not available, you could test with SPT reagent for peach that is rich in pru p 3 (but might be false positive due to other components being present. London plane and mugwort allergy would also support.
Wheat is a bit tricky – the wheat LTP Tri a 14 is only 45% homologous with Pru p 3 so may get missed. Given the co-factor issue, probably good to do Tri a 19 (omega 5 gliadin, as in exercise induced anaphylaxis) as well.
Where hay fever and atypical reactions to nuts, do the LTPs Ara h 9 (peanut), Cor a 8 (hazelnut), Jug r 3 (walnut). You would do the other components to exclude primary food allergy which can co-exist with LTP sensitisation.
Food challenges have limited use in this situation – if positive, unclear whether LTP is the cause, and if negative, perhaps because of co-factor issue! Exercise challenge?? May just need a bigger dose!
Individualize, to balance risk of reaction against dietary restriction.
Safest fruit/veg appear to be potato, carrot/root vegetables, beans, peas, melon, cashew and pistachio. Avoid pips and skin. Banana is hit and miss.
Good results with Pru p 3 sublingual and oral peach juice immunotherapy in Spain and Portugal.
Julie McCabe died in 2011 as a result of anaphylaxis to Para-Phenylenediamine (PPD) in hair dye. Black henna is known to contain PPD, so may sensitise.
=mpox (considered less stigmatising?).
Emerging infection particularly in men who have sex with men. Reached the UK in 2022.
New variant (Clade I) has high mortality, started in Central Africa but first case now reported in Europe (Sweden, 2024).
Incubation period is 21 days.
Besides blistering rash, can cause fever, myalgia, lymphadenopathy.
Smallpox vaccine considered effective.
Firstly, is there a suicide risk?
Then, consider mental health needs. Is there an alcohol or drug issue?
Are they known to social work? Are there any child protection issues for the young person? Their siblings or other family members? If young person is over 16 then consider Adult Protection measures (Scotland Act 2007).
A proper mental health assessment requires that they are physically well enough (consider intoxication, sedation, pain etc). Consider competency (which can be impaired temporarily by physical illness).
Consider:
=CVID. Another terribly named condition.
Usually presents in adulthood but about 20% in childhood. Typically recurrent infections of ears, sinuses, lungs – usual bugs, not funny ones.
Bronchiectasis may develop. In some cases granulomas develop.
Lymphadenopathy +/- splenomegaly is sometimes a feature.
Autoimmunity is an important feature – low red cells or platelets, thyroid disease.
Enteropathy and arthritis can be seen.
Low IgG, usually IgA, sometimes IgM. Functional antibodies (to pneumococcus, tetanus, Hib) low.
Immunoglobulin replacement – IVIG or subcut immunoglobulin, regularly.
Prophylactic antibiotics in some cases. Screen for infections esp chronic GI.
Symptoms of light headedness, dizziness, tunnel vision (pre-syncopal), potentially followed by collapse, which can be remembered in most cases. Can be brief posturing or clonus due to hypoxia, but only for a few seconds.
Recovery is fast, within seconds or a minute, once circulation to brain improves – requires that person is left lying on ground and not propped up!
They look pale, feel hot, but once on ground go clammy/sweaty. Heart rate and blood pressure typically low.
Common in teenagers, with growth spurt.
Can be reflex, from pain/fright/emotion. So with blood tests or immunisations, for example – NOT anaphylaxis.
Other differentials are epilepsy and POTS.
Patient/family info at www.stars.org.uk.
POTS (Postural orthostatic tachycardia syndrome) – more common in females.
Orthostatic tachycardia (NOT hypotension, which suggests vasovagal syncope), dizziness, chest pain, palpitations, headaches, dyspnoea. Sometimes bluish red discolouration in lower limbs.
No known cause, can have sudden onset in previously fit individuals. Associated with Ehlers Danlos (venous return problem?).
Can be debilitating, associated with chronic pain, sleep problems, GI symptoms. Can improve over time. Diagnosis – heart rate increases by 30 beats per minute (bpm) or more (40bpm in those aged 12-19) within 10 minutes of standing, or if it increases to more than 120bpm. “Hyperadrenergic” POTS is where BP actually goes up, rather than down.
Monitor during valsalva manoeuvre to look for autonomic dysfunction.
Increase fluid intake to 2-3L daily. Increase salt intake?
Waist high compression stockings?
Consider treatment with beta blocker, fludrocortisone, desmopressin, clonidine, modafinil, SSRI.
Early onset primary immunodeficiency, characterised by eczema, viral skin infections, eosinophilia.
Later allergy, autoimmunity and malignancy.
Getting it right is important because otherwise people end up scared of foods, cut out different foods and risk nutritional/growth problems as well as aversion in the child. Having unproven food allergies also causes huge problems for schools and nurseries, and may lead to the public becoming sceptical of true allergy, with potentially disastrous consequences.
Getting it right can identify other potential allergies; it can help estimate risk of anaphylaxis; it can help with predicting whether the allergy is going to go away or not.
EATERS method –
Other issues are age (adolescents with hay fever more likely to develop secondary pollen food syndrome type allergies), alpha-gal allergy can be delayed up to 3 hours; raw vs cooked food sometimes makes a difference; usually you already have eczema and family history of atopy.
At the end of history taking, you should have be able to assess probability of type 1 allergy. If low, you may wish to proceed straight to challenge (unless reactions sound severe). Otherwise testing may help confirm or refute.
If negative/equivocal on initial skin prick or specific IgE testing, do another test! Skin prick if negative/equivocal IgE, and vice versa.
IgE Component testing may give added information, esp where potential pollen co-sensitisation – best evidence (mostly in US population, however) for Peanut, Hazelnut, Cashew (respectively Ara h 2, Cor a 14, Ana o 3 – other components may give extra information in some cases). Jug r 1 v specific (walnut) but not v sensitive.
Challenge will be useful where results still equivocal – viz