This page is dedicated to organizing various examples of standardized exam questions whose answer is DiGeorge syndrome. While this may seem a odd practice, it is useful to see multiple examples of how DiGeorge syndrome will be characterized on standardized exams (namely the boards and the shelf exams). This page is not meant to be used as a tradition question bank (as all of the answers will be the same), however seeing the classic “test” characterization for a disease is quite valuable.
KEY CHARACTERISTICS OF THIS CONDITION (ON EXAMS)
When it comes to standardized exams, each condition has its own “code” marked by key buzzwords, lab findings, clues, etc. If you are well versed in this code you will be able to more quickly identify the condition that is being discussed, and get the right answer on the exam you are taking. Below is the “code” for DiGeorge syndrome.
- Symptoms from infection: this can take on many forms
- Recurrent infections: can be thrush or respiratory infections (however other are possible)
- Cardiac abnormalities: defects (truncous arteriousus common), murmurs, right sided aortic arch, shunts in heart, septal defects
- Abnormal facies: cleft palate, low set ears, hypoplastic/small jaw
- Hypocalcemia: caused by absent parathyroid glands. Can have signs on physical exam (Trousseau sign, Chvostek sign)
- Thymic hypoplasia: deficiency of T-cells, no thymic shadow on chest X-ray
Question # 1
A 9 month old girl is brought to the clinic because she has been having persistent diarrhea for the past 4 week.s She has lost 2.3 lb in this time period. She was born at term, and her mother’s pregnancy was uncomplicated. Since being born she has had multiple episodes of thrush and was hospitalized 3 months ago for the treatment of a parainfluenza virus infection. She is currently at the 40th percentile for length, and the 5th percentile for weight. Her temperature is currently 98.9°F. An examination shows a thick white plaque over her buccal mucousa. Her lymph nodes are not palpable. A grade 3/6 systolic murmur is heard best at the left sternal border. A clinical workup reveals that this patient has a deficiency of T lymphocytes. What could be the underlying diagnosis?
Explanation # 1
Chronic infections + T lymphocyte deficiency + heart murmur = DiGeorge syndrome
Question # 2
Seven days after the repair for a truncus arteriosus defect, a 9 day old newborn appears to be unwell. His temperature is 98.6°F, push is 135/min, respirations are 40/min, and blood pressure is 75/60 mm Hg. A physical exam reveals a small jaw as well as widely spaced eyes. The patient’s serum calcium concentration is 6.8 mg/dL. An X-ray of the chest shows cardiomegaly and there is no thymic shadow seen. What is the most likely diagnosis?
Explanation # 2
Cardiac defect + abnormal facies + thymic hypoplasia + hypocalcemia (due to absence of parathyroid glands) = DiGeorge syndrome
Question # 3
A newborn girl is put int he NICU because she becomes cyanotic. She was born at 37 weeks gestation by a repeat cesarean section in the mother. The newborn remains hypoxic even though she is given supplemental oxygen. A physical exam reveals a cyanotic and tremulous infant. She has low set ears, a small jaw, low set ears, and a cleft palate. A chest X-ray is done and shows an absent thymus. An echo is performed and confirms a truncus arteriosus. What condition might this patient have?
Explanation # 3
Abnormal facies + absent thymus + cardiac defect = DiGeorge syndrome
Question # 4
A newborn is noted to have facial dysmorphia and a cleft palate. During her clinical workup it is noted that this patient has a heart condition with a right to left shunt, and also does not have a thymic shadow that is visible on a chest X-ray. Over the course of her childhood, the patient experiences recurrent sinus and pulmonary infections. What is a possible diagnosis int his patient?
Abnormal facies + cardiac defect + absent thymus + history of recurrent infections = DiGeorge syndrome
Question # 5
A newborn male is admitted to the NICU shortly after being born. His temperature is 99.1°F, blood pressure is 75/35 mm Hg, pulse is 135 bpm, and respiration rate is 38/min. A physical exam reveals that the patient has a cleft palate. An echo is performed and demonstrates the presence of right ventricular hypertrophy, a ventral spatial defect, an overriding aorta, and also signs of pulmonary hypertension. The patients diagnosis is confirmed using fluorescence in situ hybridization (FISH). What is the diagnosis in this patient?
Abnormal facies + cardiac defect + diagnosis with FISH (chromosomal abnormality) = DiGeorge syndrome
Question # 6
A 10 day old newborn male is brought to the clinic because he is having odd movements of his right hand. His mother comments that he is also lethargic, and has not been feeding well this past week. The patient’s pas medical history is other wise normal. His vital signs are all within normal limits, but a physical exam reveals abnormal flexion of the right wrist and thumb, and extension of his fingers that occurred when his blood pressure was taken. A head and neck exam is notable for low set ears, a cleft palate. and a small jaw. A chest X-ray is notable for an absent thymic shadow. What is the likely diagnosis in this patient?
Trousseau sign (signifies hypocalcemia) + abnormal facies + absent thymic shadow = DiGeorge syndrome
Question # 7
A newborn male infant is found to have a right sided aortic arch. A physical exam reveals the presence of low-set ears, and a hypoplastic jaw. Labs are collected that reveal that the patient has hypocalcemia. What is the likely diagnosis in this patient?
Explanation # 7
Cardiac abnormalities + abnormal facies + hypocalcemia = DiGeorge syndrome
Question # 8
A 5 month old male has a history of recurrent respiratory infections. He is brought to the clinic because he currently has a runny nose and his parents are concerned. His past medical history is notable for hypocalcemia that is currently being treated with a supplement, and coarctation of the aorta that was surgically addressed when he was a newborn. A physical exam is notable for dysplastic facial features, and a broad nasal bridge. What condition does this patient most likely have?
Explanation # 8
History of recurrent respiratory infections + hypocalcemia + cardiac abnormalities + abnormal facial features = DiGeorge syndrome
Question # 9
A 4 month old female is brought to the clinic because she has a 2 day history of visible difficulty with breathing. Her parents explain that she appears ill, and that she grunts while breathing. Her vital signs are within normal limits, except for her respiration rate that is 60/min. A physical exam is notable for grunting and nasal flaring. Auscultation of the lungs reveals bronchial breath sounds and bilateral crackles. Serum studies reveal a calcium concentration of 5.5 mg/dL. A chest X-ray is ordered and it is notable for an absent thymic shadow, and diffuse, bilateral, interstitial infiltrates. A bronchoalveolar lavage is performed and makes the diagnosis of PCP pneumonia. What underlying condition does this patient likely have?
Explanation # 9
Hypocalcemia + absent thymic shadow + immunocompromised infection (PCP pneumonia) = DiGeorge syndrome
TESTABLE FACTS ABOUT THIS CONDITION (BEYOND ITS IDENTIFICATION)
Many questions on standardized exams go beyond simply recognizing the underlying condition. Often there are specific testable facts regarding some aspect of the disease’s pathophysiology/management/clincial implications that are commonly asked. Some of these are listed below:
Genetic cause of this condition:
- Chromosome deletion: Chromosome 22q11.2 microdeletion
Developmental cause of this condition: the 3rd and 4th pharyngeal pouches do not develop properly (leading to loss of parathyroids and thymus)
- The 3rd pharyngeal pouch forms the parathyroids (the inferior portion)
- The 4th pharyngeal pouch forms the thymus
Page Updated: 11.08.2016