An odds ratio (OR) is a measure of the association between an exposure and an outcome. The OR represents the odds that an outcome will occur given a particular exposure, compared to the odds of the outcome occurring in the absence of that exposure. Odds ratios are most commonly used in case-control studies, however they can also be used in cross-sectional and cohort study designs as well (with some modifications and/or assumptions). Wherea = Number of exposed casesb = Number of exposed non-casesc = Number of unexposed casesd = Number of unexposed non-casesOR=(a/c) / (b/d) = ad/bc

The most probable diagnosis in this patient would be Friedreich’s ataxia.Friedreich’s ataxia is also called spinocerebellar degeneration. It is an autosomal recessive condition. The onset of ataxia is around ten years of age. Intelligence is preserved. Cerebellar impairment, distal muscle weakness, pes cavus, hammer-toes and progressive kyphoscoliosis are present. Deep tendon reflexes are absent, particularly the ankle jerk. Loss of vibration and position sense occurs because of degeneration of the posterior columns. Hypertrophic cardiomyopathy can occur with progression to congestive cardiac failure.Other options:- Ataxia Telangiectasia: ataxia develops earlier, around two years of age, with loss of ambulation by adolescence. Nystagmus is present. Telangiectasia becomes evident by mid-childhood and is found on bulbar conjunctiva, over the bridge of the nose and on the ears. These children have an increased risk of developing lymphoreticular malignancies.- Abetalipoproteinemia: begins in childhood with steatorrhea and failure to thrive. Neurological symptoms appear in late childhood. These include ataxia, retinitis pigmentosa, peripheral neuritis, abnormalities in position and vibration sense, muscle weakness and mental retardation. Vitamin E is undetectable in serum in these patients.- Acute cerebellar ataxia: occurs in children of 1-3 years of age and is a diagnosis of exclusion. It often follows acute viral infections like varicella, coxsackievirus or echovirus by 2-3 weeks. It is an autoimmune response to a viral agent affecting the cerebellum. Prognosis is excellent with complete recovery present. Very small numbers have long term sequelae like ataxia, incoordination, speech disorder and behavioural problems.- Acute labyrinthitis: It is difficult to differentiate acute labyrinthitis from acute cerebellar ataxia in a toddler. It is associated with middle ear infections, vertigo and vomiting.

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.

A micturating cystourethrogram (MCUG) is one type of imaging test also called a voiding cystourethrogram (VCUG). The MCUG can check whether the flow of urine from the child’s bladder is being blocked, or whether it goes up the wrong way. It can help diagnose certain conditions, including vesicoureteral reflux and posterior urethral valves.

Answer: Acute Epstein Barr virus infectionThe Epstein–Barr virus is one of eight known human herpesvirus types in the herpes family, and is one of the most common viruses in humans. Infection with Epstein-Barr virus (EBV) is common and usually occurs in childhood or early adulthood.EBV is the cause of infectious mononucleosis, an illness associated with symptoms and signs like:fever,fatigue,swollen tonsils,headache, andsweats,sore throat,swollen lymph nodes in the neck, andsometimes an enlarged spleen.Although EBV can cause mononucleosis, not everyone infected with the virus will get mononucleosis. White blood cells called B cells are the primary targets of EBV infection.

Mumps presents with a prodromal phase of general malaise and fever. On examination there is usually painful parotid swelling which has high chances of becoming bilateral. In OM with effusion there are no signs of infection and the only symptom is usually hearing loss. Acute otitis externa produces otalgia as well as ear discharge and itching. Acute OM produces otalgia and specific findings upon otoscopy. In acute mastoiditis the patient experiences ear discharge, otalgia, headache, hearing loss and other general signs of inflammation.

Duchenne muscular dystrophy has an X-linked recessive pattern of inheritance. Since the first son is affected by the disease, it means that the mother is a carrier. The male children will inherit the Y chromosome from their father and the X chromosome from their mother, having 50% chances of inheriting the X chromosome with the affected gene.

Pale, bulky, malodorous stools are evidence of fat malabsorption syndrome. The diagnostic test is jejunal biopsy to rule out other differential diagnoses such as celiac disease, giardiasis or Crohn’s disease etc.

Answer: Transposition of the great arteriesTransposition of the great arteries (TGA) is the most common cyanotic congenital heart lesion that presents in neonates. The hallmark of transposition of the great arteries is ventriculoarterial discordance, in which the aorta arises from the morphologic right ventricle and the pulmonary artery arises from the morphologic left ventricle.Infants with transposition of the great arteries (TGA) are usually born at term, with cyanosis apparent within hours of birth.The clinical course and manifestations depend on the extent of intercirculatory mixing and the presence of associated anatomic lesions. Note the following:Transposition of the great arteries with intact ventricular septum: Prominent and progressive cyanosis within the first 24 hours of life is the usual finding in infants if no significant mixing at the atrial level is evident.Transposition of the great arteries with large ventricular septal defect: Infants may not initially manifest symptoms of heart disease, although mild cyanosis (particularly when crying) is often noted. Signs of congestive heart failure (tachypnoea, tachycardia, diaphoresis, and failure to gain weight) may become evident over the first 3-6 weeks as pulmonary blood flow increases.Transposition of the great arteries with ventricular septal defect and left ventricular outflow tract obstruction: Infants often present with extreme cyanosis at birth, proportional to the degree of left ventricular (pulmonary) outflow tract obstruction. The clinical history may be similar to that of an infant with tetralogy of Fallot.Transposition of the great arteries with ventricular septal defect and pulmonary vascular obstructive disease: Progressively advancing pulmonary vascular obstructive disease can prevent this rare subgroup of patients from developing symptoms of congestive heart failure, despite a large ventricular septal defect. Most often, patients present with progressive cyanosis, despite an early successful palliative procedure.

The general target of weight gain in the neonatal intensive care unit is to replicate the intrauterine growth in the third trimester, which equates to the daily weight gain of nearly 15 g/kg/day with infants receiving 120 kcal/kg/day

Haemolytic uremic syndrome belongs to a heterogeneous group of disorders characterized by a triad of thrombocytopenia, microangiopathic haemolytic anaemia, and acute kidney injury. It is one of the most common causes of renal injury in children. The clinical findings are due to thrombotic microangiopathy, which leads to arterioles and capillary wall thickening along with endothelial swelling and detachment. The significant laboratory findings include increased white cell count, raised serum urea and creatinine, increased serum LDH, decreased platelet count, haematuria, and proteinuria.

Key observations in the results:

1. Oxygen Saturation Step-Up:
   • There is a significant step-up in oxygen saturation from the right ventricle (72%) to the pulmonary artery (86%). This suggests the presence of left-to-right shunting of blood.
2. Pressure Differences:
   • The pressure in the pulmonary artery is elevated (53/13 mmHg), indicating pulmonary hypertension.

Differential Diagnosis:

1. Patent Ductus Arteriosus (PDA):
   • PDA can cause increased pulmonary blood flow, leading to a step-up in oxygen saturation in the pulmonary artery. The pulmonary artery pressures can also be elevated due to increased blood flow.
2. Primary Pulmonary Hypertension:
   • Typically presents with elevated pulmonary pressures but does not usually show a step-up in oxygen saturation.
3. Pulmonary Stenosis:
   • Would result in elevated right ventricular pressure but would not explain the step-up in oxygen saturation.
4. Septum Primum Atrial Septal Defect (ASD):
   • Would result in a step-up in oxygen saturation from the right atrium to the right ventricle, not between the right ventricle and pulmonary artery.
5. Tetralogy of Fallot:
   • Characterized by right ventricular outflow tract obstruction, VSD, right ventricular hypertrophy, and an overriding aorta. Oxygen saturation levels would typically be lower in the systemic circulation.

The most possible diagnosis is SVT. The boy is suffering from hemodynamic instability, as indicated by his cold extremities. DC cardioversion is the treatment of choice.

Tuberous sclerosis is an autosomal dominant neurocutaneous condition associated with increased psychiatric co-morbidity. It results from the mutation of TSC1 or TSC2 tumour suppressor genes. Multiple benign tumours of the brain and other vital organs are characteristic of this disease. Important findings include subependymal nodules, bone cysts, cardiac rhabdomyoma, and learning difficulties. Lisch nodules of the iris occur in neurofibromatosis.

Children are able to use a palmar grasp by the age of 6 months and use a pincer grasp by the age of 9 to 10 months. They can sit with support by 6 months and sit without support by 7 to 9 months. They can vocalize by 3 months. Stranger fear appears from 7 to 10 months. So this baby’s development is normal.

Perthes’ disease is a disease of the hip in children. It presents with pain that is typically located in the groin area. The pain is often present only during physical activity. Most children seek medical attention because of limping.

Osgood–Schlatter disease is pain caused by inflammation of the patella tendon at the tibial insertion.

Slipped upper femoral epiphysis occurs classically in adolescence (M:F = 3:2)

Eczema is an immune-mediated inflammatory condition of the skin characterized by intense pruritis and scaly rashes over the body. The impact of the disease can be measured by using certain scales, which include the Dermatitis Family Impact (DFI) Questionnaire, infant’s Dermatitis Quality of Life Index, Patient-oriented Eczema Measure, and Children’s Dermatology Life Quality Index among many others. Eczema severity questionnaire is not a recognized scale to determine eczema impact.

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.

Kawasaki disease is an acute febrile illness of early childhood characterized by vasculitis of the medium-sized arteries. Diagnostic criteria include fever of at least 5 days duration along with 4 or 5 of the principal clinical features – extremity changes, polymorphous rash, oropharyngeal changes, conjunctival injection and unilateral nonpurulent cervical lymphadenopathy.

Maternal and fetal toxoplasma infection may be avoided by advising pregnant women to wear gloves when gardening or handling cat litter and to cook meat thoroughly. Affected babies are treated with pyrimethamine, sulfadiazine, and folic acid.

Osteoid osteoma is a bone forming tumour which affects individuals in the second decade of life. The patient presents with a history of pain in the lower limbs which is mostly at night and responds to NSAIDS. If the pain doesn’t respond to NSAIDS, then other differentials should be considered.

As there is lymphadenopathy already present in this patient, doing a biopsy of the lymph nodes will rule out metastasis of any underlying tumour.

Any 2-month-old child presenting with any of the above signs, should be assessed and have a history taken and physical examination made before discharge. As these may all be signs and symptoms for a condition requiring hospitalisation.

Wolff-Parkinson-White (WPW) syndrome is a pre-excitation syndrome characterised by re-entry tachycardia that most commonly presents as a recurrent supraventricular tachycardia. ECG will show a short PR interval and a prolonged QRS complex.

Familial/inherited short stature is the most likely and commonest factor resulting in short stature among the children. Klinefelter syndrome is characterised by tall stature, widely spaces nipples and infertility. Other factors include congenital heart disease, maternal deprivation and diabetes mellitus but these are the rare causes.

Although WPW syndrome is a type of supraventricular re-entrant tachycardia, CCBs are contraindicated in its management. This is because CCBs depress AVN conduction| the current then passes through the accessory pathway (bundle of Kent) instead, causing ventricular tachycardia.

The clinical picture suggests that the child is severely dehydrated. IV fluid bolus then IV maintenance fluids is the correct option.

Patent ductus arteriosus is a heart defect that occurs in around 50% of the preterm or low birth weight infants. It is characterized by the failure of the fetal ductus arteriosus to close after birth. There are certain risk factors which predispose an infant to a patent ductus arteriosus. The most important risk factor is trisomy 21 or Down’s syndrome, which is associated with multiple cardiac defects. Other factors are congenital rubella syndrome, birth at high altitudes, and female gender.

Munchausen syndrome by proxy is a mental illness and a form of child abuse. The caretaker of a child, most often a mother or a father, either makes up fake symptoms or causes real symptoms to make it look like the child is sick. The person with MSP gains attention by seeking medical help for exaggerated or made-up symptoms of a child in his or her care. As health care providers strive to identify what’s causing the child’s symptoms, the deliberate actions of the mother or caretaker can often make the symptoms worse.The person with MSP does not seem to be motivated by a desire for any type of material gain. People with MSP may create or exaggerate a child’s symptoms in several ways. They may simply lie about symptoms, alter tests (such as contaminating a urine sample), falsify medical records, or they may actually induce symptoms through various means, such as poisoning, suffocating, starving, and causing infection.

Hereditary diseases follow specific inheritance patterns according to the type of gene involved. Mutations in the genes which are on the sex chromosome, chromosome X are called X-linked diseases. X-linked recessive conditions result when both the copies of X-chromosomes are defective, which happens in the case of females since males have only one X- chromosome. Thus, these conditions are more common among males, and examples include colour blindness, haemophilia, Lesch-Nyhan syndrome, and hunter’s syndrome, etc. Hunter’s syndrome is a type of lysosomal storage disease which is also known as mucopolysaccharidosis II. Vitamin D resistant rickets is a X-linked dominant disease. Neurofibromatosis type 1 and 2 are autosomal dominant conditions while Wilson’s disease is autosomal recessive.