Instrumentation For Fish

Metaphase Spreads

Although FISH (see Chapter 17) represents one of the most exciting and clinically significant developments of the last decade, most of the steps involved in preparing samples for analysis are unremarkable and often repetitive and, therefore, lend themselves to automation. When one considers the enormous increase in FISH sample volume most cytogenetics laboratories are experiencing, any device that can reduce the labor component of the process becomes indispensable. Fig. 5. VP 2000 processor....

Structural Chromosome Abnormalities

This category of abnormalities includes several subclasses that will be discussed under separate headings. Again, as previously stated, all chromosomes involved in abnormalities are designated in numerical order, except for the X and Y, which are listed first. When designating an abnormality that is limited to a single chromosome, the abbreviation for that abnormality is used, followed by the chromosome number in parentheses e.g., r(X), del(2), ins(4), dup(5) . If two or more chromosomes are...

Culture Failure

All culture failures must be investigated. The circumstances of the failure should be recorded as a part of an on-going quality assurance program (see Chapter 6). A record of failure rates for each specimen type in the laboratory must be kept as a baseline so that deviations from the norm can be detected. It is important to isolate the reason(s) for a culture failure so that steps can be taken to prevent future similar failures. Some culture failure is unavoidable, but adherence to strict...

Autosomal Monosomies

Triploid Karyotype

As noted in the Introduction, autosomal monosomies are extremely rare in either liveborns or abortuses, reflecting the severity of the genetic imbalance resulting from the loss of an entire chromosome. The only monosomies that have been reported are monosomy 21, mosaic monosomy 22, and a single case reported in an abstract of a possible mosaic monosomy 20 in a 31 2 year old boy with atypical speech language delay, behavior problems, microcephaly, and patchy hypopigmentation of the skin (161)....

Mainline Stemline Sideline and Clonal Evolution

These terms can be confusing and are often misunderstood. The mainline (ml) is the term used to describe the most common clone (i.e., the one represented by the most cells). This is a quantitative issue only. It does not necessarily indicate the most basic clone in tumor progression, which is referred to as the stemline (sl). Clones that evolve from the stemline are referred to as sidelines (sdl) When more than one clone is present but no clear clonal progression is evident, the mainline is...

Preanalytical Testing Components

Before a test specimen arrives in the laboratory, there are a number of steps that must be done correctly to ensure that an accurate and useful test result is provided. Laboratories often develop and provide to their clients materials to guide them in understanding when to test, what to test, and how to order tests. Often considered outside of the day-to-day functioning of the laboratory, these are important to ensuring safe and effective testing. Prior to initiating testing, there should be...

Interpreting A Karyotype Description

Receiving a cytogenetic report that contains the description of a patient's karyotype can create confusion, particularly if complex rearrangements or multiple clones are present. Interpretation of the description of a karyotype can be facilitated by breaking this description into its component parts. First, determine whether more than one cell line is present. This will happen if constitutionally the patient is a mosaic or a chimera as is often the case with acquired cytogenetic abnormalities,...

United States

Accreditation, Inspections and External Proficiency Testing Under the Clinical Laboratory Improvement Amendment of 1988 (CLIA '88), every laboratory performing moderate- to high-complexity testing (i.e., every cytogenetics laboratory) must enroll in Health and Human Services approved external inspection and testing programs. In fact, virtually all clinical laboratories in the United States do so under the auspices of the CLIA-deemed program of the College of American Pathologists (CAP). This...

Trisomy

Big Lips Genetics

Trisomy 8 47,XX or XY,+8 was first reported by Grouchy et al. in 1971 (93). It is rare, with an unknown incidence. More than 100 cases have been reported in the literature (94-97), most of them mosaics 47,+8 46 . The male-to-female ratio is 2-3 1. Growth and the degree of mental deficiency are variable. Mild to severe retardation is seen, and a proportion of patients have normal IQs. Craniofacial dysmorphism (see Fig. 8) includes prominent forehead, deep-set eyes, strabismus, broad nasal...

Partial Autosomal Aneuploidies

Pallister Killian Syndrome

Partial duplication deletion as a result of structural rearrangement is discussed in Chapter 9. Only those partial autosomal aneuploidies that result from the presence of a supernumerary chromosome will be presented in this chapter. Tetrasomy 5p 47,XX or XY, i 5 p10 resulting from the presence of a supernumerary isochromosome for the entire short arm of chromosome 5 is rare and has been reported in only three liveborns, all of whom are mosaics with both normal and abnormal cell lines 205 . The...