Hy Embryology 13 Part 2

Front 1

Describe Neurofibromatosis type I (NF1; von Recklinghausen disease)

Back 1

1. NF1 is a relatively common autosomal dominant disorder caused by a mutation in the NF1 gene on chromosome 17q11.2 for the protein neurofibronin

2. Clinical findings include multiple neural tumors (called neurfibromas), which are widely dispersed over the body and reveal proliferation of all elements of a peripheral nerve, including neurites, fibroblasts, and Schwann cells of neural crest origin, numerous pigmented skin lesions (called cafe au lait spots), probably associated with melanocytes of neural crest origin, and pigmented iris hamartomas (called Lisch nodes)

Front 2

Describe neurofibromin

Back 2

Neurofibromin downregulates p21 ras oncoprotein so that the NF1 gene belongs to the family of tumor-suppressor genes

Front 3

Describe Cafe au Lait spots

Back 3

Pigmented skin lesions associated with melanocytes of neural crest origin. These are associated with Neurofibromatosis type I

Front 4

Describe Lisch nodules

Back 4

Pigmented iris hamartomas associated with Neurofibromatosis type I

Front 5

Describe CHARGE association

Back 5

1. A genetic disorder of unknown cause but seems to involve an insult during the second month of gestation probably involving neural crest cells

2. Clinical findings include coloboma of the retina, lens, or choroid; heart defects (eg, tetralogy of Fallot, VSD, patent ductus arteriosus); atresia choanae; retardation of growth; genital abnormalities in male infants (eg, cryptorchidism, microphallus); and ear abnormalities or deafness

Front 6

Describe medullary carcinoma of thyroid

Back 6

1. Medullary carcinoid of the thyroid is an endocrine neoplasm of the parafollicular (C) cells of neural crest origin that secrete calcitonin

2. The carcinoma cells are usually arranged in cell nests surrounded by bands of stroma containing amyloid

Front 7

Describe Schwannomas

Back 7

1. A schwannoma is a benign tumor of Schwann cells of neural crest origin

2. These tumors are well circumscribed, encapsulated masses that may or not be attached to the nerve

3. The most common location within the cranial vault is at the cerebellopontine angle near the vestibular branch of CN VIII (often referred to as an acoustic neuroma)

4. Clinical findings include tinnitus and hearing loss

5. CN V (trigeminal nerve) is also commonly affected

Front 8

Describe the tumors of Schwannomas

Back 8

These tumors are well circumscribed, encapsulated masses that may or not be attached to the nerve

Front 9

Describe the most common location of Schwannomas

Back 9

The most common location within the cranial vault is at the cerebellopontine angle near the vestibular branch of CN VIII (often referred to as an acoustic neuroma)

Front 10

What are the clinical findings associated with Schwannomas?

Back 10

Clinical findings include tinnitus and hearing loss

Front 11

Describe Neurofibromatosis type I (NF1; von Recklinghausen disease)

Back 11

1. NF1 is a relatively common autosomal dominant disorder caused by a mutation in the NF1 gene on chromosome 17q11.2 for the protein neurofibronin

2. Clinical findings include multiple neural tumors (called neurfibromas), which are widely dispersed over the body and reveal proliferation of all elements of a peripheral nerve, including neurites, fibroblasts, and Schwann cells of neural crest origin, numerous pigmented skin lesions (called cafe au lait spots), probably associated with melanocytes of neural crest origin, and pigmented iris hamartomas (called Lisch nodes)

Front 12

Describe neurofibromin

Back 12

Neurofibromin downregulates p21 ras oncoprotein so that the NF1 gene belongs to the family of tumor-suppressor genes

Front 13

Describe Cafe au Lait spots

Back 13

Pigmented skin lesions associated with melanocytes of neural crest origin. These are associated with Neurofibromatosis type I

Front 14

Describe Lisch nodules

Back 14

Pigmented iris hamartomas associated with Neurofibromatosis type I

Front 15

Describe CHARGE association

Back 15

1. A genetic disorder of unknown cause but seems to involve an insult during the second month of gestation probably involving neural crest cells

2. Clinical findings include coloboma of the retina, lens, or choroid; heart defects (eg, tetralogy of Fallot, VSD, patent ductus arteriosus); atresia choanae; retardation of growth; genital abnormalities in male infants (eg, cryptorchidism, microphallus); and ear abnormalities or deafness

Front 16

Describe the cause of CHARGE association

Back 16

A genetic disorder of unknown cause but seems to involve an insult during the second month of gestation probably involving neural crest cells

Front 17

Describe the clinical findings of CHARGE association

Back 17

Clinical findings include:
1. Coloboma of the retina, lens, or choroid
2. Heart defects (eg, tetralogy of Fallot, VSD, patent ductus arteriosus)
3. Atresia choanae
4. Retardation of growth
4. Genital abnormalities in male infants (eg, cryptorchidism, microphallus)
5. Ear abnormalities or deafness

Front 18

Describe Waardenburg syndrome

Back 18

1. Waardenburg syndrome (WS) is an autosomal dominant disorder

2. It is caused by a mutation in either the PAX3 gene on chromosome 2q35 (type I WS) for a paired box PAX3 transcription factor or the MITF gene on chromosome 3p12.3-p12.3 (type II WS) for microphthalmia-associated transcription factor

3. Clinical findings include malposition of the eyelid, lateral displacement of lacrimal puncta, a broad nasal root, heterochromia of the iris, congenital deafness, and piebaldism, including a white forelock and a triagular area of hypopigmentation

Front 19

Describe the clinical findings of Waardenburg syndrome

Back 19

Clinical findings include:
1. Malposition of the eyelid
2. Lateral displacement of lacrimal puncta
3. A broad nasal root
4. Heterochromia of the iris
5. Congenital deafness
6. Piebaldism, including a white forelock and a triangular area of hypopigmentation

Front 20

Describe the cause of Waardenburg syndrome

Back 20

A mutation in either of the PAX3 gene on chromosome 2q35 (Type I WS) for a paired box PAX3 transcription factor

The MITF gene on chromosome 3p12.3-p12.3 (Type II WS) for the microphthalmia-associated transcription factor

Front 21

Describe Type I Waardenburg syndrome

Back 21

Waardenburg syndrome caused by a mutation in either the PAX3 gene on chromosome 2q35 for a paired box PAX3 transcription factor

Front 22

Describe Type II Waardenburg syndrome

Back 22

Waardenburg syndrome caused by a mutation in the MITF gene on chromosome 3p12.3-p12.3 for the microphthalmia-associated transcription factor

Front 23

When do the primary brain vesicles develop?

Back 23

Week 4

Front 24

Describe the development of primary brain vesicles

Back 24

The three primary brain vesicles and two associated flexures develop during week 4

Front 25

What are the primary brain vesicles and associated flexures?

Back 25

1. Prosencephalon (forebrain)
2. Mesencephalon (midbrain)
3. Rhombencephalon (hindbrain)
4. Cephalic flexure (midbrain flexure)
5. Cervical flexure

Front 26

Describe the prosencephalos

Back 26

1. The forebrain
2. Gives rise to the telencephalon and diencephalon

Front 27

Describe the mesencephalon

Back 27

1. The midbrain
2. Remains as the mesencephalon

Front 28

Describe the Rhombencephalon

Back 28

1. The hindbrain
2. Gives rise to the metencephalon and the myelencephalon

Front 29

Describe the Cephalic flexure

Back 29

1. The midbrain flexure
2. Located between the prosencephalon and the rhombencephalon

Front 30

Describe the cervical flexure

Back 30

Located between the rhombencephalon