Question 1

A young mother brings her 5-year-old girl who is still in diapers to the pediatrician's office.The mother complains that the infant is constantly wetting her diapers even though the girl is potty-trained.Upon examination,you notice what appears to be urine coming from the vagina through a small orifice located in the upper vaginal wall.What is your initial diagnosis?

Accepted Answer

The symptoms described are consistent with an ectopic ureter, which is a congenital anomaly where the ureter inserts into the bladder in an abnormal location. This can result in urine leaking from the vagina and bypassing the sphincter control. A rectovaginal fistula would result in fecal matter passing through the vagina. Rectovesicular and rectourethral fistulas would result in urine and fecal matter passing through the vagina. A unicornate uterus is a congenital anomaly of the uterus and would not result in the symptoms described.

Question 2

Mutations in particular genes can cause or increase the risk of specific congenital anomalies of the urogenital system.Which gene when mutated is most likely to be responsible for autosomal dominant polycystic kidney disease?

Accepted Answer

Mutations in the PDK1 gene (also known as PKD1) are most commonly associated with autosomal dominant polycystic kidney disease (ADPKD).

Question 3

The collecting tubules of the definitive kidney are derived from what tissue (cells)?

Accepted Answer

The collecting tubules of the definitive kidney are derived from the ureteric buds. The ureteric bud grows into the metanephric mesenchyme and undergoes branching morphogenesis to form the collecting duct system, including the collecting tubules.

Question 4

Which developing kidney system ultimately becomes the definite kidney in humans?

Accepted Answer

In the development of the human kidney, three systems are present sequentially – pronephric kidney, mesonephric kidney, and metanephric kidney. However, in humans, the pronephric and mesonephric kidney are non-functional and eventually degenerates. The metanephric kidney is the definitive, functional kidney that develops and replaces the non-functional kidneys. Therefore, the correct choice is C, the metanephric kidney.

Question 5

Mutations in particular genes can cause or increase the risk of specific congenital anomalies of the urogenital system.Which gene when mutated is most likely to be responsible for male pseudohermaphrodism?

Accepted Answer

Mutations in the 5α F.-reductase gene are known to cause male pseudohermaphroditism. This gene encodes an enzyme that converts testosterone to dihydrotestosterone (DHT), which is necessary for the development of male external genitalia. Mutations in this gene can lead to reduced levels of DHT and incomplete masculinization of the external genitalia.

Question 6

An ultrasound of a 7-month-pregnant woman reveals the presence of oligohydramnios.Closer examination suggests that the fetus has bilateral renal agenesis.What could have led to the development of this congenital anomaly?

Accepted Answer

Bilateral renal agenesis is caused by the absence of both kidneys due to the failure of the ureteric bud to interact with the metanephric blastema during renal development. This leads to the absence of amniotic fluid (oligohydramnios) as well, since fetal urine is the main source of amniotic fluid.

Question 7

Mutations in particular genes can cause or increase the risk of specific congenital anomalies of the urogenital system.Which gene when mutated is most likely to be responsible for persistent müllerian syndrome?

Accepted Answer

Mutations in the AMH receptor gene can lead to persistent müllerian syndrome, also known as persistent müllerian duct syndrome, where the müllerian ducts do not regress properly in males during embryonic development, resulting in the presence of a uterus, fallopian tubes, and cervix in individuals with XY chromosomes.

Question 8

Mutations in particular genes can cause or increase the risk of specific congenital anomalies of the urogenital system.Which gene when mutated is most likely to be responsible for congenital bilateral aplasia of the vas deferens?

Accepted Answer

Congenital bilateral aplasia of the vas deferens (CBAVD) is most commonly caused by mutations in the cystic fibrosis transmembrane conductance regulator gene (CFTR). Mutations in this gene can also cause cystic fibrosis, a disease that affects multiple organ systems including the lungs, pancreas, and reproductive organs. Mutations in the other genes listed (AMH receptor, WT1, 5α F.-reductase, PDK1) are associated with different urogenital anomalies, but not CBAVD.

Question 9

What gene is thought to be a direct downstream target of SRY expression?

Accepted Answer

SOX9 is a transcription factor that is known to be directly regulated by SRY expression. It plays a critical role in male sex determination and development.

Question 10

What renal structure arises via a mesenchymal-to-epithelial transition?

Accepted Answer

The nephron, which is the functional unit of the kidney, arises via a mesenchymal-to-epithelial transition during fetal development. This process involves the transformation of mesenchymal cells into epithelial cells, which differentiate into the various cell types of the nephron, including the glomerulus, tubules, and collecting ducts.

Question 11

Mutations in particular genes can cause or increase the risk of specific congenital anomalies of the urogenital system.Which gene when mutated is most likely to be responsible for glomerulopathy associated with Denys-Drash syndrome?

Accepted Answer

WT1 (Wilms tumor 1) gene mutations are associated with Denys-Drash syndrome, a rare genetic disorder characterized by genitourinary abnormalities, including glomerulopathy. Mutations in the CFTR gene are involved in cystic fibrosis, while mutations in the AMH receptor gene are associated with male pseudohermaphroditism. Mutations in the 5αF-reductase gene are associated with ambiguous genitalia, and mutations in the PDK1 gene are associated with polycystic kidney disease.

Question 12

A 4-year-old child was diagnosed with nephroblastoma,a kidney tumor.Subsequent genetic analysis of the child showed the presence of a mutation in a gene known to be associated with the development of this tumor but having a required role in renal development.What gene is it?

Accepted Answer

The gene associated with the development of nephroblastoma (Wilms' tumor) is the WT1 (Wilms' tumor suppressor) gene. Mutations in this gene are a common cause of the disease. The WT1 gene plays a critical role in normal kidney development, and mutations in this gene can lead to the development of tumors. RET is associated with multiple endocrine neoplasia type 2 (MEN2) syndrome, AMH is associated with male sexual differentiation, SOX9 is involved in the development of the testes, and SHH is involved in the development of the nervous system.

Question 13

What effect would a loss of Shh expression within the urethral plate have on genital development?

Accepted Answer

Loss of Shh expression in the urethral plate would lead to hypospadia, a condition where the urethral opening is not at the tip of the penis or clitoris, but further down the shaft. This is because Shh is essential for proper urethral tube formation, and its loss can disrupt urethral plate development. The other choices are not directly related to Shh expression in the urethral plate.

Quiz 16: Development of the Urogenital System