The most probable diagnosis for this patient’s symptoms is psoriasis.

Psoriasis:
Chronic plaque psoriasis is characterised by pinkish-red hyperkeratotic plaques, which occur mainly on extensor surfaces such as knees and elbows. The lower back, ears and scalp can also be involved.

Koebner phenomenon: Psoriasis typically exhibits this phenomenon where new plaques of psoriasis occur particularly at sites of skin trauma.

Diagnosis:
Skin biopsy of psoriatic plaques reveals acanthosis and parakeratosis, reflecting increased skin turnover. Capillary dilatation within the dermis also occurs, surrounded by a mixed neutrophilic and lymphohistiocytic perivascular infiltrate.

In the prenatal heart, right-to-left atrial shunting of blood through the foramen ovale is essential for proper circulation. After birth, as the pulmonary circulation is established, the foramen ovale functionally closes as a result of changes in the relative pressure of the two atrial chambers, ensuring the separation of oxygen-depleted venous blood in the right atrium from the oxygenated blood entering the left atrium.

Among the options provided, bradycardia is a feature of raised intracranial pressure.

The features of raised intracranial pressure include relative bradycardia and hypertension, altered consciousness, focal neurology and seizures.

All other options are signs of shock but not raised intracranial pressure.

Pulmonary surfactant is a lipoprotein complex that is responsible for preventing the collapse of alveoli and increasing lung compliance.
It is produced in the endoplasmic reticulum and secreted from the lamellar bodies of type 2 pneumocytes.

Surfactant is essential for reducing surface tension at the air-water interface in the alveoli, thus preventing the collapse of alveoli during expiration. It is composed of dipalmitoyl phosphatidylcholine (DPPC), which is a phospholipid.

In fetal development, production of surfactant begins around 26 weeks of gestation and reaches mature levels by 35 weeks.
The deficiency of surfactant can result in neonatal respiratory distress syndrome or hyaline membrane disease, particularly in premature new-born babies.

In the pattern of mendelian inheritance, X- linked dominant inheritance means that all who inherit the X chromosome will present with the condition. In the case of maternal x-linked inheritance sons and daughters have an equal chance of inheriting the condition as there is a 50% chance of inheriting the defective X chromosome from their mother as opposed to a non affected X chromosome from their father. However in paternal X-linked dominant inheritance, sons will be unaffected as they inherit a Y chromosome from their father while daughters are sure to inherit the defective X-chromosome.

The baby most likely has umbilical granuloma – granulation tissue may persist at the base of the umbilicus after cord separation; the tissue is composed of fibroblasts and capillaries and can grow to more than 1 cm.
Medical therapy is indicated only when an infection is present.
Silver nitrate application to umbilical granulomas is usually successful. One or more applications may be needed. Care must be taken to avoid contact with the skin. Silver nitrate can cause painful burns. Small umbilical granulomas with a narrow base may be safely excised in the office setting. Large granulomas and those growing in response to an umbilical fistula or sinus do not resolve with silver nitrate and must be surgically excised in the operating room setting.

Intussusception is one of the common causes of intestinal obstruction in children, resulting from the invagination or telescoping of one segment of the bowel into the other distal segment. It may induce bowel ischemia and necrosis, as well. It can occur as a complication of Meckel’s diverticulum. It usually occurs proximal to the ileocecal valve, and the most common presentation is ileocecal. Early signs and symptoms include cramping abdominal pain, nausea, vomiting, and pulling legs up to chest area. First line treatment includes resuscitation with IV fluids and nasogastric tube. It responds well to air-enema, which is also diagnostic.

Standard deviation is defined as the measure of dispersion of a set of data from its mean. It measures the absolute variability of a distribution; the higher the dispersion or variability, the greater is the standard deviation and greater will be the magnitude of the deviation of the value from their mean.

Tuner’s syndrome is not associated with arachnodactyly.

Arachnodactyly is seen in the following conditions:
– Marfan syndrome
– Homocystinuria
– Ehlers-Danlos syndrome
– Congenital contractural arachnodactyly

Other rare syndromes include:
– Loeys-Dietz syndrome
– Antley-Bixler syndrome
– Marden-Walker syndrome
– Lujan-Frinz syndrome
– Haim-Munk syndrome
– Marden-Walker syndrome
– Spondylocostal dysostosis

Findings described are suggestive of Waterhouse-Friderichsen syndrome which develops secondary to meningococcaemia. The reported incidence of Addison’s disease is 4 in 100,000. It affects both sexes equally and is seen in all age groups. It tends to show clinical symptoms at the time of metabolic stress or trauma. The symptoms are precipitated by acute infections, trauma, surgery or sodium loss due to excessive perspiration.

Erythema Migrans is associated with Lyme disease, a tic transmitted infection caused by the spirochete Borrelia Burgdorferi. The rash usually appears at the bite site after 7 to 10 days. It is flat or slightly raised and migrates as the name suggests.

Streptococcal throat infection and Crohn’s disease are both associated with erythema nodosum.

Herpes simplex and Rheumatic fever may present with Erythema Multiforme and Erythema Marginatum respectively.

Cot death also know as SIDS or Sudden Infant Death syndrome. Putting a baby to sleep on his back has been shown to reduce the risk of SIDS.

Cafe-au-lait spots is hyperpigmented lesions that vary in colour from light brown to dark brown, with borders that may be smooth or irregular. Causes include:

Neurofibromatosis type I

McCune-Albright syndrome

Legius syndrome

Tuberous sclerosis

Fanconi anaemia

Idiopathic

Ataxia-telangiectasia

Basal cell nevus syndrome

Benign congenital skin lesion

Bloom syndrome

Chediak-Higashi syndrome

Congenital nevus

Gaucher disease

Hunter syndrome

Maffucci syndrome

Multiple mucosal neuroma syndrome

Noonan syndrome

Pulmonary Stenosis

Silver-Russell syndrome

Watson syndrome

Wiskott-Aldrich syndrome

Mild deficiencies of 21-hydroxylase or 3-beta-hydroxysteroid dehydrogenase activity may present in adolescence or adulthood with oligomenorrhea, hirsutism, and/or infertility. This is termed nonclassical adrenal hyperplasia.
Late-onset or nonclassical congenital adrenal hyperplasia (NCAH) due to 21-hydroxylase deficiency is one of the most common autosomal recessive disorders. Reported prevalence ranges from 1 in 30 to 1 in 1000. Affected individuals typically present due to signs and symptoms of androgen excess.
Treatment needs to be directed toward the symptoms. Goals of treatment include normal linear growth velocity, a normal rate of skeletal maturation, ‘on-time’ puberty, regular menstrual cycles, prevention of or limited progression of hirsutism and acne, and fertility. Treatment needs to be individualized and should not be initiated merely to decrease abnormally elevated hormone concentrations.
Normal Ultrasound rules out Turner’s syndrome.

Fragile X syndrome is a genetic condition that causes a range of developmental problems including learning disabilities and cognitive impairment. Usually, males are more severely affected by this disorder than females.
Affected individuals usually have delayed development of speech and language by age 2. Most males with fragile X syndrome have mild to moderate intellectual disability, while about one-third of affected females are intellectually disabled. Children with fragile X syndrome may also have anxiety and hyperactive behaviour such as fidgeting or impulsive actions. They may have attention deficit disorder (ADD), which includes an impaired ability to maintain attention and difficulty focusing on specific tasks. About one-third of individuals with fragile X syndrome have features of autism spectrum disorder that affect communication and social interaction. Seizures occur in about 15 percent of males and about 5 percent of females with fragile X syndrome.
Most males and about half of females with fragile X syndrome have characteristic physical features that become more apparent with age. These features include a long and narrow face, large ears, a prominent jaw and forehead, unusually flexible fingers, flat feet, and in males, enlarged testicles (macroorchidism) after puberty.

Using a Doppler device, you can estimate systolic BP even when the pulse is inaudible. Handheld and portable, the device uses ultrasound waves to detect the velocity of arterial blood flow. Helpful for patients with traumatic injuries or shock, the Doppler technique is also useful for children and patients whose BP is hard to hear because of oedema, obesity, vasoconstriction, or low cardiac output.

Non-Hodgkin Lymphoma: The history is of enlarged reticuloendothelial system with abnormalities in all 3 cell lines of the bone marrow (pallor, fever and petechiae). The most likely diagnosis is therefore acute (lymphoblastic) leukaemia. Lymphadenopathy may be prominent: mediastinal nodes are characteristic of T-cell leukaemia. In lymphoma the marrow involvement tends to be much less.

At 7 months, children are expected to sit briefly leaning forward on their hands, reach and grasp objects, transfer objects from hand to hand, and babble. Children are usually expected to wave goodbye or grasp objects with their fingers or thumb at around 10 months and older.

People with Systemic Juvenile Idiopathic Arthritis (also known as Stills disease) can have recurrent fevers, a macular rash, joint pain, joint deformities, an enlarged liver and/or spleen, and can occasionally have polyserositis, lung involvement or pericardial effusions. Rheumatoid factor and antinuclear antibodies are usually negative. Treatment is with non-steroidal anti-inflammatory drugs (NSAIDs) and the prognosis is better than for adult rheumatoid arthritis.
In pauciarticular Still’s disease, antinuclear antibodies are present. Large joints are affected and most patients develop classic features of seronegative spondylarthritis.

The boy presented with mild hypoglycaemia and should be managed at home with fast-acting carbs. He should not sleep immediately. His parents should monitor his blood glucose every hour without letting him sleep in between.

Case control studies are used to determine the relationship between exposure to a risk factor and the resultant outcomes. It finds patients in the general population who have a certain condition and retrospectively searches for past exposure to possible risk factors for the disease. Controls are people who do not have the disease found in the general population. This type of study is useful for rare diseases, and is less time consuming to conduct.

While cohort studies can be used to study rare diseases they measure the relative risk of developing the disease over time based on exposure.

Ecological or cross-sectional studies attempt take a snapshot of a whole population, and thus are inappropriate for rare diseases as larger sample numbers are needed. A randomised control trial is better suited to determine the effect of an intervention.

The initial symptoms of spasmodic abdominal pain, rectal bleeding and vomiting might point towards intussusception, but the peak incidence is in children aged 6-9 months. Considering that this child has additional symptoms of haematuria, proteinuria and a purpuric rash, it is more likely that the child has Henoch-Schonlein purpura (HSP). HSP is an identifiable cause of intussusception.
It is an IgA-mediated, autoimmune hypersensitivity vasculitis that targets the small vessels of the skin, GI tract, kidneys, and joints. It is most commonly seen in children aged 3 – 6years and is twice as common in boys than girls. Preceding viral URTI with low-grade pyrexia is common. The most common organism associated with HSP is, however, Group A streptococcal infection. A purpuric rash is seen on the back of the legs and buttocks and can less frequently, affect the arms. Arthralgia is common (usually knees/ankles) in these patients. Abdominal pain and bloody diarrhoea may occur. And half of the children with HSP have renal involvement. Rarely, it can lead to end-stage renal failure.
Treatment includes adequate hydration, occasionally steroids, and other immunosuppressants. The disease can recur in 1 in 3 children.

The anti-B antibodies in a patient with blood group A belong to the IgM class of immunoglobulins.

Note:
IgM is the largest antibody formed of 5 antibodies attached together. This functions to agglutinate or clump antigens.
The associated anti-A and anti-B antibodies are usually IgM produced in the first years of life by sensitisation to environmental substances such as food, bacteria, and viruses.

Other options:
– IgG is the most common antibody. It is a single antibody complex.
– IgD is found on the surface of B-lymphocytes.
– IgE is bound to tissue cells, especially mast cells and eosinophils.

Erythema multiforme is a skin rash characterized by the eruption of macules, papules, and target-like lesions. The target or iris lesions appear rounded with a red centre surrounded by a pale ring, which in turn is surrounded by a dark red outer ring. These are acute and self-limiting, mostly appearing on the distal extremities along with palmoplantar involvement. The disease affects the mucous membrane and orbits as well. The most common infectious cause is herpes simplex virus 1 and 2 to a lesser extent. Inflammation of the adipocytes underlying the skin is referred to as erythema nodosum, and it is not a feature of EM.

Primitive reflexes are central nervous system responses, many of which disappear as a child matures. Retention of these reflexes may point to atypical neurology such as in cerebral palsy or stroke. However, some persist into adulthood. The stepping reflex is present from birth and normally disappears by 6 weeks, while the moro reflex is present from birth to about 4 months. The asymmetrical tonic neck reflex disappears by about 6 months. Reflexes that persist include the head righting reflex which develops at 6 months, and the parachute reflex which develops at 9 months.

Certain CHDs may present with a differential cyanosis, in which the preductal part of the body (upper part of the body) is pinkish but the post ductal part of the body (lower part of the body) is cyanotic, or vice versa (reverse differential cyanosis). The prerequisite for this unique situation is the presence of a right-to-left shunt through the PDA and severe coarctation of the aorta or aortic arch interruption or severe pulmonary hypertension. In patients with severe coarctation of the aorta or interruption of the aortic arch with normally related great arteries, the preductal part of the body is supplied by highly oxygenated pulmonary venous blood via the LA and LV, whereas the post ductal part is supplied by deoxygenated systemic venous blood via the RA, RV, main pulmonary artery (MPA) and the PDA. In the new-born with structurally normal heart, a differential cyanosis may be associated with persistent pulmonary hypertension of the new-born. In the cases of TGA with coarctation of the aorta or aortic arch interruption, the upper body is mostly supplied by systemic venous blood via the RA, RV, and ascending aorta, whereas the lower body is supplied by highly oxygenated pulmonary venous blood via the LA, LV, MPA, and then the PDA. For accurate detection of differential cyanosis, oxygen saturation should be measured in both preductal (right finger) and post ductal (feet) parts of the body.

Stevens-Johnson syndrome (SJS) is a type of severe skin reaction. The most common cause is certain medications such as lamotrigine, carbamazepine, allopurinol, sulphonamide antibiotics, and nevirapine.

The patient’s sugar levels typically show the Dawn phenomenon.

Dawn phenomenon:
This is an early morning rise in blood glucose levels secondary to a rise in hormones that increase blood glucose levels. The question suggests that he is undergoing a pubertal growth spurt, suggesting that an increase in these hormones is what has led to the higher morning glucose levels.

Other options:
– Inactivity at night-time: It is expected, and insulin dose should be adequate despite inactivity during the night.
– Inadequate bedtime insulin: It is possible that this is a contributing factor. However, inadequate background insulin is also likely to result in high blood glucose in the day, which the question does not suggest.
– Somogyi effect: There are no features suggestive of nocturnal hypoglycaemia that can cause the Somogyi effect.
– Nocturnal glycogenesis: Glycogenesis would result in hypoglycaemia, not hyperglycaemia.

Alpha-fetoprotein (AFP) is a plasma protein produced by the embryonic yolk sac and the fetal liver. AFP levels in serum, amniotic fluid, and urine functions as a screening test for congenital disabilities, chromosomal abnormalities, as well as some other adult occurring tumours and pathologies.
Pregnant maternal serum AFP levels are elevated in:
– Neural tube defects (e.g., spina bifida, anencephaly)
– Omphalocele
– Gastroschisis
– posterior urethral valves
– nephrosis
– GI obstruction
– teratomas

Histology of psoriasis is characterised by parakeratosis (cell nuclei within stratum corneum) and thickened projections of the prickle cell layer of keratinocytes (psoriasiform hyperplasia or acanthosis).

Orthokeratosis refers to the formation of a pathological anuclear keratin layer in the skin.

The stratum granulosum is actually thinned or absent in patients with psoriasis.