Hello, I'm Dr. Simon Holden.
I'm a consultant in clinical genetics in
the Department of Clinical Genetics at Addenbrooke's Hospital, in Cambridge.
I am also an associate lecturer at the University of Cambridge.
This presentation is on Chromosome Disorders.
Chromosome disorders are common,
and it's important that students learn about them.
With this talk, we'll be looking at the science of
chromosome analysis and how this relates to clinical practice,
then some of the more important clinical features of
these conditions that we can encounter in the clinic.
At the end of this lecture,
students should be familiar with the different types of chromosome disorders and
understand how they relate to other genomic disorders,
which we'll cover in other lectures;
be familiar with the nomenclature used to
describe the more common chromosome rearrangements;
understand how the behaviour of
chromosome rearrangements at meiosis dictate their inheritance,
and, therefore, their recurrence risks;
and be able to describe a chromosome rearrangement,
and its clinical implications to a patient.
So, chromosome disorders are common;
numerical anomalies are by far the most frequent.
These include autosomal trisomies, sex chromosome anomalies,
unbalanced structural rearrangements,
triploidy, and also structurally balanced rearrangements.
Overall, in unselected newborns,
approximately 0.9 percent of infants will have some form of chromosome anomaly.
Up to 20 percent of oocytes and 10 percent of sperm
have chromosome number anomalies known as aneuploidy.
This means that up to one to three conceptuses- so that's
recognized pregnancies- are trisomic or monosomic.