It is well known that healthy males typically have one X chromosome and one Y chromosome and healthy females normally have two X chromosomes. Syndrome de la Chapelle called also “XX male syndrome” is a pretty rare sex chromosomal disorder (sex inversion) – congenital condition in which male phenotype is combined with female karyotype 46XX. XX males have two X chromosomes with one of them containing genetic material from their Y chromosome, making them phenotypically male but genetically female. XX males have two X chromosomes but otherwise appear to be male. Actually person looks like man but genetically it is a woman with female karyotype (46XX). It could be a great problem during Olympic games when person should be identified for female or male world records.
Dr Albert de la Chapelle
This syndrome was described in 1972 by famous Finish scientist Dr Albert de la Chapelle – characterized as a state of complete or partial masculinization with presence of testicular tissue in the absence of typical male Y-chromosome in the karyotype.Usually this syndrome caused by unequal crossing over between X and Y chromosomes during meiosis in the father which results in the X chromosome containing the normally-male SRY gene. When this X combines with a normal X from the mother during fertilization, the baby becomes XX male. Most typical symptoms are small testes, gynecomastia (noncancerous increase in the size of male breast tissue) and infertility.
In general population de la Chapelle syndrome occurs in approximately 4-5 in 100 000 individuals.
Syndrome de la Chapelle – causes
According to scientists, the 46 XX gender inversion happens because of translocation of a small segment of the short arm of Y-chromosome carrying the SRY gene to X-chromosome or the autosome. The presence of SRY-gene in the genome of men with 46XX causes phenotypic development of the body in the male type (condition called de la Chapelle syndrome). Scientists noted presence of a small Y-chromosome fragment including SRYin a karyotypic XX genome.
Syndrome de la Chapelle – risks of inheritance
Any man could have incorrect recombination of chromosomal material (appearance of 46XX men containing the SRY gene). Parents of the child with syndrome de la Chapelle usually have low risk of repeating sex inversion in future children. But since certain mutations of the SRY-gene have incomplete penetrance, healthy fertile fathers can carry SRY-gene mutations that can cause sex inversion in their children with the XY genotype (so called “Svayer Syndrome”).
Syndrome de la Chapelle – symptoms
Syndrome de la Chapelle
Typical symptoms of XX male syndrome include the following:
Hypogonadism (diminished functional activity of testes) – hypergonadotropic type;
Puberty in boys with de la Chapelle syndrome begins on their own but deficit of testosterone could create problems in full normal virilization. Boys with syndrome de la Chapelle have normal growth, normal skeletal proportions, normal intellect and some psychological problems.
Syndrome de la Chapelle – diagnosis
Final diagnosis can be confirmed only after clinical, hormonal and genetic tests.
Clinically patient looks like male with small testes, limited secondary sexual characteristics (poor face hair growth and limited hair on pubic area), increased breasts (female type), decreased libido, erectile dysfunctions and fertility problems. Client mention episodes of depression and low mood.
Hormonal tests confirm hypogonadism (hypergonadotropic type) and decreased levels of testosterone.
Sperm analysis demonstrate azoospermia (absence of spermatozoids in semen).
Genetic test identify 46XX and fluorescence in situ hybridization (FISH) or polymerase chain reaction (PCR) techniques may detect the SRY gene.
Diagnosis during pregnancy (so called “antenatal diagnosis”) is possible. Prenatal testing in pregnancies at risk for SRY-positive 46,XX testicular DSD can be done in qualified clinics.
Syndrome de la Chapelle – treatment
Male hormones (mainly testosterone) can be recommended during de la Chapelle syndrome – it will contribute to adequate virilization (secondary sexual characteristics). Testosterone replacement therapy is able to correct hormonal imbalance, prevent gynecomastia and to induce development of male secondary sex characteristics
Modern medicine is not able to treat azoospermia during syndrome de la Chapelle but assisted reproductive technologies (ART) can provide several solution for future reproductive plans including IUI – Artificial Intrauterine Insemination and sperm donation.
For gynecomastia surgical treatment can be recommended (mammoplasty).
Psycho-social counseling is recommended starting from puberty.
Syndrome de la Chapelle – prognosis
Prognosis depends on clinical symptoms and psychological status of client. Hormonal treatment, assisted reproductive technologies and psychological counseling can fully adapt person with de la Chapelle syndrome to society. They can have ordinary life with family and children. But people with syndrome de la Chapelle need care, full understanding and support.
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Disclaimer: It is strongly recommended to consult your doctor for professional advice. Above mentioned information and recommendations are just general and should be adapted to each person according to personal health indicators and status.