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Leydig cell hypoplasia

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Leydig cell hypoplasia

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Leydig cell hypoplasia
Other names	46,XY DSD due to luteinizing hormone resistance or luteinizing hormone beta subunit deficiency

This condition is inherited in an autosomal recessive manner

Leydig cell hypoplasia (or aplasia) (LCH), also known as Leydig cell agenesis, is a rare autosomal recessive genetic and endocrine syndrome affecting an estimated 1 in 1,000,000 genetic males. It is characterized by an inability of the body to respond to luteinizing hormone (LH), a gonadotropin which is normally responsible for signaling Leydig cells of the testicles to produce testosterone and other androgen sex hormones. The condition manifests itself as pseudohermaphroditism (partially or fully underdeveloped genitalia), hypergonadotropic hypogonadism (decreased or lack of production of sex steroids by the gonads despite high circulating levels of gonadotropins), reduced or absent puberty (lack of development of secondary sexual characteristics, resulting in sexual infantilism if left untreated), and infertility.

Leydig cell hypoplasia does not occur in biological females as they do not have either Leydig cells or testicles. However, the cause of the condition in males, luteinizing hormone insensitivity, does affect females, and because LH plays a role in the female reproductive system, it can result in primary amenorrhea or oligomenorrhea (absent or reduced menstruation), infertility due to anovulation, and ovarian cysts.

A related condition is follicle-stimulating hormone (FSH) insensitivity, which presents with similar symptoms to those of Leydig cell hypoplasia but with the symptoms in the respective sexes reversed (i.e., hypogonadism and sexual infantilism in females and merely problems with fertility in males). Despite their similar causes, FSH insensitivity is considerably less common in comparison to LH insensitivity.

Symptoms and signs

The symptoms of Leydig cell hypoplasia include pseudohermaphroditism, i.e., feminized, ambiguous, or relatively mildly underdeveloped (e.g., micropenis, severe hypospadias, and/or cryptorchidism [undescended testes]) external genitalia, a female gender identity or gender variance, hypergonadotropic hypogonadism (hypogonadism despite high levels of gonadotropins), delayed, impaired, or fully absent puberty with an associated reduction in or complete lack of development of secondary sexual characteristics (sexual infantilism), impaired fertility or complete sterility, tall stature (due to delayed epiphyseal closure), eunuchoid skeletal proportions, delayed or absent bone maturation, and osteoporosis.

Cause

A 46,XY (genetically "male") woman with complete insensitivity to LH, resulting in fully feminized genitalia at birth. Puberty appears to have commenced, likely due to estrogen replacement therapy.

Leydig cell hypoplasia is caused by genetic mutations in LHCGR, a gene which encodes the LH/hCG receptor. LH normally acts through the LH/hCG receptor to stimulate the growth of Leydig cells in the testicles and the production of androgens such as testosterone and dihydrotestosterone (DHT) by these cells. In Leydig cell hypoplasia however, there is a reduced capacity for the LH/hCG receptor to respond to LH. This results in hypoplasia or absence of Leydig cells, testicular atrophy, and lower than normal androgen levels. In the most severe form of the condition in which there is a complete lack of response of the Leydig cells to LH, androgen production by the testicles is virtually negligible and secondary sexual characteristics entirely fail to develop at puberty.

Diagnosis

Since the Sertoli cells are not affected by Leydig cell hypoplasia, anti-Müllerian hormone is secreted normally and so there are no Müllerian structures. Wolffian structures, such as the prostate, vasa deferentia, and epidydimides are present. In type I, abdominal testes are revealed on ultrasound; in type II testes may be descended or undescended.

People with Leydig cell hypoplasia type I display no response to the hCG stimulation test; there is no increase in serum levels of testosterone and dihydrotestosterone. Leydig cell hypoplasia type II can display either a pronounced rise of testosterone levels or no rise.

In any case, the diagnosis is confirmed on biopsy of the testes, revealing either absent or hypoplastic Leydig cells. The inside of the testis will be grayish and mucous, displaying arrested spermatogenesis and the presence of Sertoli cells. The diagnosis can also be confirmed by looking for mutations in the gene for the LH receptor.

A diagnosis of Leydig cell hypoplasia is usually made in the neonatal period, following the discovery of ambiguous genitalia, or at puberty, when secondary sex characteristics fail to develop. Puberty is the most common time for Leydig cell hypoplasia to be diagnosed.

Treatment

Patients with Leydig cell hypoplasia may be treated with hormone replacement therapy (i.e., with androgens), which will result in normal sexual development and the resolution of most symptoms. In the case of 46,XY (genetically "male") individuals who are phenotypically female and/or identify as the female gender, estrogens should be given instead. Surgical correction of the genitals in 46,XY males may be required, and, if necessary, an orchidopexy (relocation of the undescended testes to the scrotum) may be performed as well.

External links

Classification	D ICD-10: Q56.1 OMIM: 238320 MeSH: C562567 DiseasesDB: 30830
External resources	MedlinePlus: http://ghr.nlm.nih.gov/condition/leydig-cell-hypoplasia Orphanet: 755

Pituitary disease

Hyperpituitarism

Anterior	Acromegaly Hyperprolactinaemia Pituitary ACTH hypersecretion
Posterior	SIADH
General	Nelson's syndrome Hypophysitis

Hypopituitarism

Anterior	Kallmann syndrome Growth hormone deficiency Hypoprolactinemia ACTH deficiency/Secondary adrenal insufficiency GnRH insensitivity FSH insensitivity LH/hCG insensitivity
Posterior	Neurogenic diabetes insipidus
General	Empty sella syndrome Pituitary apoplexy Sheehan's syndrome Lymphocytic hypophysitis Pituitary adenoma

Genetic disorders relating to deficiencies of transcription factor or coregulators

(1) Basic domains

1.2	Feingold syndrome Saethre–Chotzen syndrome
1.3	Tietz syndrome

(2) Zinc finger
DNA-binding domains

2.1	(Intracellular receptor): Thyroid hormone resistance Androgen insensitivity syndrome PAIS MAIS CAIS Kennedy's disease PHA1AD pseudohypoaldosteronism Estrogen insensitivity syndrome X-linked adrenal hypoplasia congenita MODY 1 Familial partial lipodystrophy 3 SF1 XY gonadal dysgenesis
2.2	Barakat syndrome Tricho–rhino–phalangeal syndrome
2.3	Greig cephalopolysyndactyly syndrome/Pallister–Hall syndrome Denys–Drash syndrome Duane-radial ray syndrome MODY 7 MRX 89 Townes–Brocks syndrome Acrocallosal syndrome Myotonic dystrophy 2
2.5	Autoimmune polyendocrine syndrome type 1

(3) Helix-turn-helix domains

3.1	ARX Ohtahara syndrome Lissencephaly X2 MNX1 Currarino syndrome HOXD13 SPD1 synpolydactyly PDX1 MODY 4 LMX1B Nail–patella syndrome MSX1 Tooth and nail syndrome OFC5 PITX2 Axenfeld syndrome 1 POU4F3 DFNA15 POU3F4 DFNX2 ZEB1 Posterior polymorphous corneal dystrophy Fuchs' dystrophy 3 ZEB2 Mowat–Wilson syndrome
3.2	PAX2 Papillorenal syndrome PAX3 Waardenburg syndrome 1&3 PAX4 MODY 9 PAX6 Gillespie syndrome Coloboma of optic nerve PAX8 Congenital hypothyroidism 2 PAX9 STHAG3
3.3	FOXC1 Axenfeld syndrome 3 Iridogoniodysgenesis, dominant type FOXC2 Lymphedema–distichiasis syndrome FOXE1 Bamforth–Lazarus syndrome FOXE3 Anterior segment mesenchymal dysgenesis FOXF1 ACD/MPV FOXI1 Enlarged vestibular aqueduct FOXL2 Premature ovarian failure 3 FOXP3 IPEX
3.5	IRF6 Van der Woude syndrome Popliteal pterygium syndrome

(4) β-Scaffold factors
with minor groove contacts

4.2	Hyperimmunoglobulin E syndrome
4.3	Holt–Oram syndrome Li–Fraumeni syndrome Ulnar–mammary syndrome
4.7	Campomelic dysplasia MODY 3 MODY 5 SF1 SRY XY gonadal dysgenesis Premature ovarian failure 7 SOX10 Waardenburg syndrome 4c Yemenite deaf-blind hypopigmentation syndrome
4.11	Cleidocranial dysostosis

(0) Other transcription factors

0.6	Kabuki syndrome

Ungrouped

Transcription coregulators

Coactivator:	CREBBP Rubinstein–Taybi syndrome
Corepressor:	HR (Atrichia with papular lesions)

Inborn errors of steroid metabolism

Mevalonate
pathway

HMG-CoA lyase deficiency

Hyper-IgD syndrome
Mevalonate kinase deficiency

To cholesterol

desmosterol path: Desmosterolosis

Steroids

Corticosteroid
(including CAH)

aldosterone: Glucocorticoid remediable aldosteronism

Sex steroid

To androgens	17α-Hydroxylase deficiency 17,20-Lyase deficiency Cytochrome b₅ deficiency 3β-Hydroxysteroid dehydrogenase deficiency 17β-Hydroxysteroid dehydrogenase deficiency 5α-Reductase 2 deficiency Pseudovaginal perineoscrotal hypospadias
To estrogens	Aromatase deficiency Aromatase excess syndrome

Other

Cell surface receptor deficiencies

G protein-coupled receptor
(including hormone)

Class A	TSHR (Congenital hypothyroidism 1) LHCGR (Luteinizing hormone insensitivity, Leydig cell hypoplasia, Male-limited precocious puberty) FSHR (Follicle-stimulating hormone insensitivity, XX gonadal dysgenesis) GnRHR (Gonadotropin-releasing hormone insensitivity) EDNRB (ABCD syndrome, Waardenburg syndrome 4a, Hirschsprung's disease 2) AVPR2 (Nephrogenic diabetes insipidus 1) PTGER2 (Aspirin-exacerbated respiratory disease)
Class B	PTH1R (Jansen's metaphyseal chondrodysplasia)
Class C	CASR (Familial hypocalciuric hypercalcemia)
Class F	FZD4 (Familial exudative vitreoretinopathy 1)

Enzyme-linked receptor
(including
growth factor)

RTK	ROR2 (Robinow syndrome) FGFR1 (Pfeiffer syndrome, KAL2 Kallmann syndrome) FGFR2 (Apert syndrome, Antley–Bixler syndrome, Pfeiffer syndrome, Crouzon syndrome, Jackson–Weiss syndrome) FGFR3 (Achondroplasia, Hypochondroplasia, Thanatophoric dysplasia, Muenke syndrome) INSR (Donohue syndrome Rabson–Mendenhall syndrome) NTRK1 (Congenital insensitivity to pain with anhidrosis) KIT (KIT Piebaldism, Gastrointestinal stromal tumor)
STPK	AMHR2 (Persistent Müllerian duct syndrome II) TGF beta receptors: Endoglin/Alk-1/SMAD4 (Hereditary hemorrhagic telangiectasia) TGFBR1/TGFBR2 (Loeys–Dietz syndrome)
GC	GUCY2D (Leber's congenital amaurosis 1)