Lesch-Nyhan syndrome is a condition that occurs almost exclusively in males. This condition is inherited in an X-linked recessive pattern It is characterized by neurological and behavioural abnormalities and the overproduction of uric acid. Uric acid is a waste product of normal chemical processes and is found in blood and urine. Excess uric acid can be released from the blood and build up under the skin and cause gouty arthritis (arthritis caused by an accumulation of uric acid in the joints). Uric acid accumulation can also cause kidney and bladder stones.The nervous system and behavioural disturbances experienced by people with Lesch-Nyhan syndrome include abnormal involuntary muscle movements, such as tensing of various muscles (dystonia), jerking movements (chorea), and flailing of the limbs (ballismus). People with Lesch-Nyhan syndrome usually cannot walk, require assistance sitting, and generally use a wheelchair. Self-injury (including biting and head banging) is the most common and distinctive behavioural problem in individuals with Lesch-Nyhan syndrome.

The most likely causative organism for the symptoms of this child is Giardia lamblia.Giardiasis results in fat malabsorption thus giving rise to greasy stools. It is resistant to chlorination, hence has a risk of transfer in swimming pools.World Health Organisation definitions- Diarrhoea: > 3 loose or watery stool per day- Acute diarrhoea < 14 days- Chronic diarrhoea > 14 daysConditions that usually present as acute diarrhoea:- Gastroenteritis: It may be accompanied by abdominal pain or nausea/vomiting.- Antibiotic therapy: Can occur following antibiotic therapy, especially common with broad spectrum antibiotics.Conditions that usually present as chronic diarrhoea:- Irritable bowel syndrome: It is a very common disease.The most consistent features are abdominal pain, bloating and change in bowel habit. Patients may be divided into those with diarrhoea predominant IBS and those with constipation-predominant IBS.Features such as lethargy, nausea, backache and bladder symptoms may also be present in these patients.- Ulcerative colitis: It presents as bloody diarrhoea. Patients can also present with crampy abdominal pain and weight loss. Faecal urgency and tenesmus may be seen.- Crohn’s disease: It is also associated with crampy abdominal pains and diarrhoea. Bloody diarrhoea less common than in ulcerative colitis. Other features include malabsorption, mouth ulcers perianal disease and intestinal obstruction – Colorectal cancer: It is very rare in children. The symptoms depend on the site of the lesion but include diarrhoea, rectal bleeding, anaemia and constitutional symptoms like weight loss and anorexia.- Coeliac disease: In children, it may present with failure to thrive, diarrhoea and abdominal distension.Other conditions associated with diarrhoea include thyrotoxicosis, laxative abuse, appendicitis, and radiation enteritis.

The autosomal dominant pattern of inheritance involves the presence of at least one of the defected copies of the gene in an individual to develop a specific diseased condition. Examples of this mode of inheritance include myotonic dystrophy, neurofibromatosis, achondroplasia, etc. Still’s disease, also called juvenile idiopathic arthritis, is not a heritable disease. Tay-Sachs disease is an autosomal recessive disease., while spinocerebellar ataxia and Friedreich’s ataxia are caused by trinucleotide repeat expansion.

HLA-DR (3 and 4) have been associated with an increased risk for idiopathic diabetes mellitus.Type 1 diabetes has a high heritability compared to type 2Identical twins have a 30-50% risk if their twin has type 1 diabetes

Erythema nodosum is the most common type of inflammation of the subcutaneous fat tissue, referred to as panniculitis. Erythema nodosum appears as painful, erythematous round lumps, usually symmetrically on the anterior aspect of lower extremities. These lesions are self-limiting and tend to resolve within 2-8 weeks without undergoing necrosis or ulceration. There are various causes of erythema nodosum, but the most important among children is the streptococcal throat infection. Other causes include autoimmune conditions like sarcoidosis, inflammatory bowel disease, mycobacterial infection (TB), drugs like penicillin and sulphonamides, and malignancies like some leukemias and lymphomas.

DiGeorge syndrome usually presents at a young age with abnormal faces. Chest x-ray is characterised by an absent thymic shadow and recurrent infections due to an abnormal T-cell mediated immune response. Sometimes it presents by convulsions of the new-born due to hypocalcaemia as a result of a malfunctioning parathyroid gland and low levels of PTH.

Morphea, also known as localized scleroderma, is a disorder characterized by excessive collagen deposition leading to thickening of the dermis, subcutaneous tissues, or both. Morphea is classified into circumscribed, generalized, linear, and pansclerotic subtypes according to the clinical presentation and depth of tissue involvement. Unlike systemic sclerosis, morphea lacks features such as sclerodactyly, Raynaud phenomenon, nailfold capillary changes, telangiectasias, and progressive internal organ involvement. Morphea can present with extracutaneous manifestations, including fever, lymphadenopathy, arthralgias, fatigue, central nervous system involvement, as well as laboratory abnormalities, including eosinophilia, polyclonal hypergammaglobulinemia, and positive antinuclear antibodies.

Anorexia nervosa is an eating disorder which is characterized by distorted self-image leading to abnormally decreased calorie intake. This disorder affects multiple bodily systems, including the skin, GI, and endocrine system. Due to extreme weight loss, patients with anorexia nervosa develop cold intolerance along with bluish discoloration of their fingers, nose, and ears, which is known as acrocyanosis. This phenomenon may be due to the shunting of the blood from the peripheries to the central body systems as a reaction to hypothermia. Other notable changes in the integumentary system include extreme dryness (xerosis), lanugo hairs, decubitus ulcers, and easy bruisibility.

Von Hippel-Lindau syndrome is a genetic disorder inherited in autosomal dominant fashion. It is caused by the mutations of the VHL gene located on chromosome 3. The syndrome is characterized by the creation of multiple benign and malignant tumours involving various bodily systems along with the formation of numerous visceral cysts, including the renal and epididymal cysts. Down’s syndrome is associated with renal cysts, but it does not follow the autosomal dominant mode of inheritance, rather it is caused by non-disjunction of chromosome 21 during meiosis. Exomphalos is a defect of the medial abdominal wall leading to abnormal protrusion of abdominal viscera through it. It is not associated with renal cysts. Turner’s syndrome may be associated with renal cysts formation, but it is not transmitted in an autosomal dominant fashion. Polycystic kidney disease of childhood follows an autosomal recessive pattern of transmission.

All the given development milestones are compatible with the given age.

Based on the clinical scenario provided, this patient most probably has impacted gall stones. Gall stones in children can be caused by haematological diseases such as sickle cell anaemia and thalassemia. Cholesterol stones are also becoming more prevalent. A dilated common bile duct (> 10mm in adults) suggests gall stone impaction. The presence of pyrexia indicates cholecystitis.

The most appropriate next step in the management would be to refer the patient for an ENT opinion. Rationale:This child has clinical signs of adenotonsillar hypertrophy, symptoms of persistent snoring and features of obstructive sleep apnoea (OSA). Suspected OSA warrants referral to an ENT specialist. Other options:- Capillary blood gas: The investigation consists of overnight oxygen saturation monitoring or polysomnography.- Chest X-ray: A chest x-ray is not indicated.- Phenoxymethylpenicillin (Penicillin V) is the first-line treatment for tonsillitis. However, with a history of several months and no suggestion of fever or sore throat, acute tonsillitis is unlikely.- Weight loss advice: Obesity is a risk factor for obstructive sleep apnoea (OSA) amongst other health problems. The child’s weight should be highlighted and advice and support for weight loss provided however referral to ENT is warranted for further investigation.

The clinical presentation of the boy suggests the involvement of the right frontal lobe.Psychiatric or behavioural disturbances secondary to frontal lobe lesions exhibit lateralisation. The lesions of the left hemisphere are associated with depression, especially if the lesion involves the dorsolateral portion of the prefrontal cortex. Whereas, lesions of the right hemisphere are associated with impulsivity, disinhibition, and aggression, as it is the case with the child in question.Presenting symptoms of lobar dysfunctions:- Frontal lobe: Contralateral hemiplegia, impaired problem solving, disinhibition, and lack of initiative. Broca’s aphasia and agraphia suggest the involvement of the dominant hemisphere.- Temporal lobe: Wernicke’s aphasia (dominant hemisphere involvement), homonymous upper quadrantanopia and auditory agnosia (non-dominant hemisphere involvement).- Parietal lobe: Anosognosia, dressing apraxia, spatial neglect and constructional apraxia are observed when the non-dominant hemisphere is involved. Gerstmann’s syndrome is observed when the dominant hemisphere is involved.- Occipital lobe: Visual agnosia, visual illusions and contralateral homonymous hemianopia.

WHO states that diabetes can be diagnosed from a single fasting glucose of > 7.0 mmol/l with characteristic symptoms or a glucose level of > 11.1 mmol/l 2 hours after a glucose load. Two fasting glucose levels of > 7.0 mmol/l on separate occasions can also fit the diagnosis in the absence of characteristic symptoms.

Nephrogenic Diabetes Insipidus is an acquired or hereditary condition that affects the water balance. It presents with polyuria and polydipsia, leading commonly to dehydration.

Tetralogy of Fallot usually is diagnosed after a baby is born, often after the infant has an episode of turning blue during crying or feeding (a tet spell). A loud heart murmur is usually present.An atrial septal defect is present at birth, but many babies do not have any signs or symptoms.Coarctation of the aorta is usually diagnosed after the baby is born. How early in life the defect is diagnosed usually depends on how mild or severe the symptoms are. New-born screening using pulse oximetry during the first few days of life may or may not detect coarctation of the aorta.In babies with a more serious condition, early signs usually include:pale skinirritabilityheavy sweatingdifficulty breathingBabies born with pulmonary atresia will show symptoms at birth or very soon afterwards. They may be cyanotic. However, it is not uncommon for a heart murmur to be absent right at birth.

Atrial septal defects may also occur in association with a variety of other congenital heart defects, or in new-borns that are relatively small or premature. The following conditions are associated with an atrial septal defect:Ebstein’s anomalyFoetal alcohol syndromeHolt-Oram syndromeDown syndromeEllis van Creveld syndromeLutembacher’s syndrome Ostium primum defects occur frequently in individuals with Down syndrome or Ellis van-Creveld syndrome.Holt-Oram syndrome characterized by an autosomal dominant pattern of inheritance and deformities of the upper limbs (most often, absent or hypoplastic radii) has been attributed to a single gene defect in TBX5Fragile X syndrome is characterized by moderate intellectual disability in affected males and mild intellectual disability in affected females. The physical features in affected males are variable and may not be obvious until puberty. These symptoms can include a large head, long face, prominent forehead and chin, protruding ears, loose joints and large testes. Other symptoms can include flat feet, frequent ear infections, low muscle tone, a long narrow face, high arched palate, dental problems, crossed eyes (strabismus) and heart problems including mitral valve prolapse.

NICE guidelines suggest that when a child’s single risk factor is 2 vomits, the child should be observed for 4 hours from the time of the injury, instead of having a CT.

Classic Kallmann syndrome (KS) is due to isolated hypogonadotropic hypogonadism. Most patients have gonadotropin-releasing hormone (GnRH) deficiency, as suggested by their response to pulsatile GnRH therapy. The hypothalamic-pituitary function is otherwise normal in most patients, and hypothalamic-pituitary imaging reveals no space-occupying lesions. By definition, either anosmia or severe hyposmia is present in patients with Kallmann syndrome.

The signs and symptoms of vitamin D-dependent rickets begin within months after birth, and most are the same for all types of the condition. The weak bones often cause bone pain and delayed growth and have a tendency to fracture. When affected children begin to walk, they may develop abnormally curved (bowed) legs because the bones are too weak to bear weight. Impaired bone development also results in widening of the metaphysis, especially in the knees, wrists, and ribs. Some people with vitamin D-dependent rickets have dental abnormalities such as thin tooth enamel and frequent cavities. Poor muscle tone (hypotonia) and muscle weakness are also common in this condition, and some affected individuals develop seizures.

NICE guidelines suggest that at the premonitory stage (pre-hospital) the patient should receive Diazepam 10�20 mg given rectally, or midazolam 10 mg given buccally. If seizures continue, the patient should receive lorazepam IV.

The Kaplan-Meier estimator, also known as the product limit estimator, is a non-parametric statistic used to estimate the survival function from lifetime data. In medical research, it is often used to measure the fraction of patients living for a certain amount of time after treatment.

The most common organism responsible for tinea capitis is Trichophyton tonsurans.Tinea is a term given to dermatophyte fungal infections. There are three types of tinea, depending on what part of the body is infected:- Tinea capitis – scalp- Tinea corporis – trunk, legs or arms- Tinea pedis – feet-Tinea capitis (scalp ringworm): It is a cause for scarring alopecia mainly seen in children. If untreated, it can form a raised pustular, spongy/boggy mass called a kerion. The most common cause of tinea capitis in the UK and the USA is Trichophyton tonsurans. Tinea can also be caused by Microsporum canis acquired from cats or dogs.The diagnosis of tinea capitis and identification of the organism is possible from the skin lesions: – Scalp scrapings and Potassium hydroxide (KOH) mounts.- Wood’s lamp: Microsporum canis produces a green fluorescence under Wood’s lamp examination.Treatment: – Oral antifungals: terbinafine for Trichophyton tonsurans infections.- Griseofulvin for Microsporum infections. – Topical ketoconazole shampoo is recommended for the first two weeks to limit the transmission of the infection.

The diagnosis of scabies can often be made clinically in patients with a pruritic rash and characteristic linear burrows. Definitive testing relies on the identification of mites or their eggs, eggshell fragments, or scybala. This is best undertaken by placing a drop of mineral oil directly over the burrow on the skin and then superficially scraping longitudinally and laterally across the skin with a scalpel blade. (Avoid causing bleeding.) Scraping 15 or more burrows often produces only 1 or 2 eggs or mites, except in a case of crusted scabies, in which many mites will be present. The sample is placed on a microscope slide and examined under low and high power. Potassium hydroxide should not be used, since it can dissolve mite pellets. Failure to find mites is common and does not rule out the diagnosis of scabies.

Ectoderm derivatives include the adrenal medulla, posterior pituitary, the epidermis of the skin, nails, hair, sweat glands, mammary glands, sebaceous glands, the central nervous system, the peripheral nervous system, the retina and lens of eye, the pupillary muscle of the iris, melanocytes, Schwann cells and odontoblasts.

The clinical scenario provided is highly suggestive of third-degree burns (or full-thickness burns) that may have invaded the deeper levels up to dermis, evident from the insensate nature of the lesion.Degrees of Burns:- First degree burns are superficial second-degree burns.- Second-degree burns are just deeper than that of first-degree burns but vary enormously in other properties.- Third-degree burns are full-thickness burns which are leathery in consistency, and insensate. These burns do not heal on their own. The sensory neurons present in the skin at the deeper levels are destroyed completely and hence provide a paradoxical lack of pain.- Fourth-degree burns involving the subcutaneous tissues, tendons, and bones are very difficult to manage.Assessment of the extent of the burns for the treatment employs specialized charts, such as Lund and Browder charts and Wallace rule of nines.The Lund and Browder chart is, however, considered the most accurate.Wallace’s Rule of Nines can be used for children >16 years: – Head + neck = 9%- Each arm = 9%- Each anterior part of leg = 9%- Each posterior part of leg = 9%- Anterior chest = 9%- Posterior chest = 9%- Anterior abdomen = 9%- Posterior abdomen = 9%

The structure in question is the rectus sheath. This sheath encloses the rectus abdominis muscle and thus, will be encountered by the surgeon.Note:- Midline incision: It is the most common approach to the abdomen. The structures divided during this incision are linea alba, transversalis fascia, extraperitoneal fat, and peritoneum ( with care taken to avoid the falciform ligament above the umbilicus).The bladder can be accessed via an extraperitoneal approach through the space of Retzius.- Paramedian incision: It is an incision that is made parallel to the midline. The structures divided or retracted are anterior rectus sheath, rectus (retracted), posterior rectus sheath, transversalis fascia, extraperitoneal fat, and peritoneum.- Battle incision: It is similar to a paramedian but the rectus is displaced medially (and thus denervated).- Kocher’s incision: It is an incision made under the right subcostal margin, e.g. cholecystectomy (open).- Lanz incision: It is an incision in the right iliac fossa, e.g. appendicectomy.Gridiron incision: It is an oblique incision centred over the McBurney’s point – usually used for appendicectomy (less cosmetically acceptable than LanzPfannenstiel’s incision: It is a transverse suprapubic incision, primarily used to access pelvic organs.McEvedy’s incision: It is a groin incision used for emergency repair strangulated femoral hernia.Rutherford Morrison incision: It provides an extraperitoneal approach to left or right lower quadrants. It provides excellent access to iliac vessels and is the approach of choice for first-time renal transplantation.

This patient might have viral meningitis as he recently suffered viral parotitis(Mumps). Microscopy and culture of the CSF would show a CSF lymphocytosis.

Unprotected anal or vaginal sexual intercourse with an infected individual is by far the most common (95%) route by which HIV is transmitted. Other options:- Blood transfusion is an extremely rare cause of HIV transmission in the UK. – While HIV can be transmitted from mother to baby either during birth or via breastfeeding, the transmission rate is only 5 -20%.- Sharing contaminated needles does put individuals at risk of getting HIV, although public health measures are in place to reduce this risk. – Although HIV can be transmitted via this route, it is around ten times less likely to result in transmission than unprotected anal or vaginal intercourse with an infected individual.

Aplastic anaemia causes a deficiency of all blood cell types: red blood cells, white blood cells, and platelets. It is more frequent in people in their teens and twenties, but is also common among the elderly. It can be caused by heredity, immune disease, or exposure to chemicals, drugs, or radiation. However, in about one-half of cases, the cause is unknown.The definitive diagnosis is by bone marrow biopsy; normal bone marrow has 30-70% blood stem cells, but in aplastic anaemia, these cells are mostly gone and replaced by fat.First-line treatment for aplastic anaemia consists of immunosuppressive drugs, typically either anti-lymphocyte globulin or anti-thymocyte globulin, combined with corticosteroids, chemotherapy and ciclosporin. Hematopoietic stem cell transplantation is also used, especially for patients under 30 years of age with a related matched marrow donor.