Cytogenetics report for g banded karyotype

Running Head: KARYOTYPE

2

KARYOTYPE

Belinda Mensah

Oluwatobi Omobo

Bowie State University

Dr. Burks

General Genetics

Karyotypes (Lab)

Examining Human Chromosome Disorder

The role of a Cytogenetist is to study chromosomes by the aid of a microscope (Brooker 2019). A Cytogenetist collects blood samples from different members of a particular species/family, then examines each chromosome to detect the origin of an abnormal finding or disease. This process of blood sampling and chromosome examination may be referred to as karyotyping. Robert Brooker of Concepts of Genetics defines a karyotype as a “micrograph in which all of the chromosomes within a single cell have been arranged in a standard fashion” (2019).

Listing the steps of karyotyping may seem easy yet requires the complex skills and knowledge of a trained Cytogenetist to perform the task. According to Brooker (2019), the steps of constructing a karyotype are:

· Collecting blood samples that are treated with colchicine and subjected to a centrifuge. The purpose of adding colchicine is to prevent the formation of spindles and the process of mitosis. The centrifuge is used to separate blood cells.

· The separated blood cells are kept in a hypotonic solution, allowing them to swell and expand.

· A second centrifuge is applied to the blood cells suspended in the hypotonic solution, allowing them to concentrate.

· The concentrated white blood cells are fixated, stained and transferred to a slide to be viewed and analyzed under a microscope by a Cytogenetist.

Cytogenetics Reports for G-Banded Karyotype-I

Patient Name: Sherry

Case ID: K

Age: 23

Why is the patient being referred for karyotyping?

To determine the source of heart defect and cleft palate in the fetus.

Source of Cells for Karyotyping

____ Blood

__YES__ Amniocytes

____ Chorionic Villi

____ Other (specify) __________________

Total Number of Chromosomes Observed: 23 pairs

Gender: Male

Chromosomal Findings

____ no observable chromosomal abnormalities

____ monosomy (chromosome #____)

____ trisomy (chromosome #____)

____ deletion (chromosome #____, arm _____)

____ insertion (chromosome #____, arm _____)

____ translocation (chromosome #s____ and ____)

____ inversion (chromosome #____, arm(s) _____)

__YES__ other (explain): Microdeletion Syndrome

Diagnosis:

22q11.2 Microdeletion Syndrome

Source: Dr. Tyesha Burks

Cytogenetics Reports for G-Banded Karyotype-I

Patient Name: Jocelyn

Case ID: C

Age: 41

Why is the patient being referred for karyotyping?

Diagnostic testing by amniocentesis

Source of Cells for Karyotyping

____ Blood

__YES__ Amniocytes

____ Chorionic Villi

____ Other (specify) __________________

Total Number of Chromosomes Observed: 23 pairs

Gender: PLEASE INSERT

Chromosomal Findings

____ no observable chromosomal abnormalities

____ monosomy (chromosome #____)

____ trisomy (chromosome #____)

____ deletion (chromosome #____, arm _____)

____ insertion (chromosome #____, arm _____)

__YES__ translocation (chromosome #s_14___ and __21__)

____ inversion (chromosome #____, arm(s) _____)

____other (explain)___________________________

Diagnosis

Robertsonian translocation

Source: Hasanzadeh-NazarAbadi, Baghbani, Namazi, and Mirzaee, 2014

Cytogenetics Reports for G-Banded Karyotype-I

Patient Name: Marie

Case ID: B

Age: 37

Why is the patient being referred for karyotyping?

To detect if fetus has a defect due to maternal age

Source of Cells for Karyotyping

____ Blood

__YES__ Amniocytes

____ Chorionic Villi

____ Other (specify) __________________

Total Number of Chromosomes Observed: 47

Gender: Female

Chromosomal Findings

____ no observable chromosomal abnormalities

____ monosomy (chromosome #____)

__YES__ trisomy (chromosome #_21___)

____ deletion (chromosome #____, arm _____)

____ insertion (chromosome #____, arm _____)

____ translocation (chromosome #s____ and ____)

____ inversion (chromosome #____, arm(s) _____)

____other (explain)___________________________

Diagnosis

Down Syndrome

Source: Stanford Children’s Health: Down Syndrome (Trisomy 21)

Case Study Analysis

For case study K, Ms. Sherry is a 23-year-old female whose ultrasound detected a heart defect and cleft palate of a male fetus. She was referred for karyotyping to determine the source of these defects.

Since this is a fetus, the source of cells for karyotyping were amniocytes through a process called amniocentesis. The total number of chromosomes observed were 23 pairs. Chromosomal findings show a microdeletion syndrome, which aided the Cytogenetist to conclude that the male fetus has a 22q11.2 microdeletion syndrome.

According to the U.S National Library of Medicine (2013), 22q11.2 microdeletion syndrome, “is a disorder caused by the deletion of a small piece of chromosome 22 [which] occurs near the middle of the chromosome at a location designated q11.2., affecting almost any part of the body”. The presence of a heart defect and a cleft palate in Sherry’s fetus are one of the few hallmarks of 22q11.2 deletion syndrome. Other signs are autoimmune disorders, seizures, recurrent infections, hearing loss and feeding difficulties (U.S National Library of Medicine 2013).

Sherry must be advised that the “life expectancy may be affected, particularly if a severe heart defect exists” (Kerr & Rope 2014). Since Sherry’s fetus is not fully developed, it may be difficult to determine the degree of the heart the defect currently present. Children with 22q11.2 deletion syndrome usually have developmental delays in speech, growths and learning, as such “the degree of intellectual disability will determine the [fetus] ability to function independently as an adult” (Kerr & Rope 2014), making it difficult for Sherry to decide if she wants to keep the pregnancy or not.

22q11.2 deletion syndrome is an autosomal dominant trait (U.S National Library of Medicine 2013). Meaning that only one trait is needed to show the signs and symptoms of the syndrome. The U.S National Library of Medicine (2013) assert that even though the syndrome is an autosomal dominant trait, most cases are not inherited, but its occurrence randomly happens.

Sherry should be aware that there is no cure to 22q11.2 deletion syndrome, but her fetus symptoms can be managed, if she decides to keep the pregnancy to full term. To prevent future complications, managing symptoms and frequent medical care will be needed through screenings, immunizations, frequent doctor visits and possibly one on one home health care for those with severe disabilities (Kerr & Rope 2014). Immunization is key because most children with 22q11.2 deletion syndrome have compromised immune systems which makes it difficult for them to fight simple infections that may not even require medical interventions. Ongoing clinical trials are also available across the United States.

Lynne Ker and Alan Rope (2014) assert that frequent anticipatory guidance and advocating for the child are various ways to boost the child’s morale since they are going to face challenges among their peers. Frequent genetic counseling will be a lifetime screening process for Sherry and her fetus. Sherry and her partner will need further testing to determine if they have the autosomal dominant trait of 22q11.2 deletion syndrome, and if so, they may want to possibly explore other options of reproduction. If Sherry’s fetus’s syndrome is not genetically linked, then the possibility of the deletion randomly occurring should be considered. As such, if the child is born, ongoing genetic counseling will be needed. Unfortunately, the reality of managing this syndrome is costly, and most children with the disorder are at risk for being neglected. A few support groups are the National Organization for Rare Diseases (NORD), The International 22q11.2 Foundation Inc. and The 22q Family Foundation.

References

Brooker, R. J. (2019). Concepts of genetics (3rd ed.). New York, NY: McGraw-Hill Education.

Hasanzadeh-NazarAbadi, M., Baghbani, F., Namazi, I., & Mirzaee, S. (2014). Robertsonian translocation between chromosomes (no.21/14) in relation to the history of spontaneous abortion in a family. Iranian journal of reproductive medicine, 12(8), 581-5.

Rope, A., & Kerr, L. (2014, July). 22q11.2 Deletion Syndrome. Retrieved March 04, 2019, from https://www.medicalhomeportal.org/diagnoses-and-conditions/22q11.2-deletion-syndrome#Authorstagless

Stanford Children's Health. (n.d.). Retrieved from https://www.stanfordchildrens.org/en/topic/default?id=down-syndrome-trisomy-21-90-P02356

U.S National Library of Medicine. (2013, July). 22q11.2 deletion syndrome - Genetics Home Reference - NIH. Retrieved from https://ghr.nlm.nih.gov/condition/22q112-deletion-syndrome