Klinefelter (XXY) & Turner Syndrome (Gonadal Dysgenesis) – Pediatric Genetics | Lecturio


[Music] in this lecture we will discuss Klinefelter syndrome and Turner syndrome these are genetic problems with the sex chromosomes so let’s start with Klinefelter syndrome these patients usually have male hypogonadism they have two or more X chromosomes and one or more Y chromosomes most commonly two x’s and one Y like you can see in this patient’s karyotype this occurs in 1 out of 650 live births so it’s not that uncommon this is generally due to maternal or paternal nondisjunction during meiosis as they’re making either the sperm or the egg this is there’s a slightly increased risk of this happening in mothers who have are of advanced maternal age sometimes Klinefelter syndrome patients are fertile and can go on to have their own children fertile Klinefelter syndrome patients have a low recurrence of Klinefelter syndrome in their offspring but the offspring do carry a very small increased risk of chromosomal abnormalities so let’s review the clinical features of Klinefelter syndrome they often suffer infertility they may have hypogonadism with small testes they often have gynecomastia in adolescence as a result of an imbalance between testosterone and estrogens you’ll notice they have reduced body hair they will be tall and have a pear-shaped stature to them and they occasionally have educational and psychological problems so how do we diagnose Klinefelter syndrome if we suspect a patient might have it well first we will send a karyotype or an array comparative genomic hybridization this will make our definitive diagnosis we will also screen these patients when they are adult males for infertility that’s useful then for them to know about for often they have a decreased sperm count it’s important to check that testosterone levels they will often have a decreased testosterone in the face of hyper no trap tropism in other words they have hyper gonadotropic hypogonadism their testes are non-responsive to LH and FSH so they have high LH and FSH hormone levels so how do we improve these patients lives the first thing that’s very important is they should receive testosterone therapy this will help a number of things especially their facial and body hair issues it will improve their strength and muscle size it will improve their energy level it will help them with libido issues it will help them with confidence and it will help them with concentration so we often will refer these patients to reproductive specialists or infertility specialists as well to help them with various reproductive options if they should decide to have a child so let’s focus now on Turner syndrome Turner syndrome is a pulse partial or complete monotony of the X chromosome this results in hypogonadism in the phenotypic female the instance is about one in two thousand live births so how does this happen well more than 60 percent are due to a de novo mitotic nondisjunction in the paternal sex chromosomes so the dad has an X and a Y and instead of splitting into one X and one Y sperm there’s basically an X Y sperm and an empty sperm and the empty sperm now then goes and fertilizes the egg creating a single X chromosome Turner sinem occurs essentially only in females males can be mosaic for Turner syndrome this is rare but it can happen where a male has some cells that are 45 X and other cells that are 46 X Y so what are the symptoms and females of Turner syndrome these are important to remember these patients will have a delayed puberty they will often have amenorrhea this is from go nate’ll dysfunction they may have premature ovarian failure this results in infertility and some patients may have some learning disabilities especially in math but generally these patients are cognitively normal patients with Turner syndrome may have short stature in fact they almost always do they have low set ears a low hairline and you may notice a webbed neck or a broadened neck root additionally you can see small jaw a shield chest which is a broadened or widened chest often with widened space nipples you may see cubed Asahi’s or outward turned elbows they may have a horseshoe kidney internally which they may not even know about and they can develop congenital heart disease so how do we test and when do we test for Turner syndrome you should consider attempting prenatal diagnosis if the fetal ultrasound shows intrauterine growth restriction fetal edema a coarctation of the aorta or cystic hygroma in this case if a parent wishes to do prenatal testing we generally do chorionic villus sampling or amniocentesis with karyotype postnatally the diagnosis is made by karyotype or AC GH just like in Klinefelter syndrome so what therapy do we provide these patients after initial leave died making the diagnosis we will screen them generally with an echocardiogram or a renal ultrasound especially paying attention to any abnormalities of the heart such as a or tech problems or if there’s an abnormal kidney additionally we will typically check them for their thyroid function we’ll do an eye exam and we’ll assess for scoliosis which is a little bit more common in these patients it’s important to refer these patients to a pediatric endocrinologist for hormonal replacement these patients will receive estrogen progestin and growth hormone if you look at this picture here are two patients with Turner syndrome the one on the Left received no growth hormone and the one on the right received growth hormone growth hormone is indicated in this patients and can really help them in terms of achieving an important stature the reason why we give it is because for patients who don’t achieve 5 feet of height this can result in significant impairments and their ability to function in the world it may be simply hard for them to drive a car we want these patients to live the most fulfilled lives they can it’s also important to refer these patients to fertility specialists for consideration of their reproductive options when they enter into adulthood so that’s my review of Turner syndrome and Klinefelter syndrome thanks for your time [Music]

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