Trichorrhexis nodosa is a defect in the hair shaft characterized by thickening or weak points (nodes) that cause the hair to break off easily. : 766 : 636  This group of conditions contributes to the appearance of hair loss, lack of growth, and damaged-looking hair. Symptoms
Among the symptoms (and signs) for this condition are the following:

lack of apparent hair growth
hair appears patchy
hair breaks easily close to scalp
hair may have thickenings or nodes in the shaft
ends of hair thinned or split
whitish discoloration of hair tips
hair breaks easily at tips

Complications
This condition is not dangerous but may affect self-esteem. Causes
Trichorrhexis may have a genetic basis but appears to be precipitated by environmental factors. Among Caucasians the defect often appears at the ends of the hair shaft with splitting of the ends, thinning and whitish discoloration. These conditions are directly related to environmental causes such as "perming", blow drying, aggressive hair brushing, and excessive chemical exposure. In some cases, trichorrhexis nodosa may be caused by an underlying disorder such as argininosuccinic aciduria, Menkes kinky hair syndrome, Nethertons syndrome, hypothyroidism,  or trichothiodystrophy. Diagnosis
Examination of the hair shafts with a microscope may reveal changes of trichorrhexis nodosa. Prevention
Avoid aggressive brushing and grooming, strong chemicals, permanents, straightening, and similar hair-damaging habits. Treatment
Improving environmental factors will reduce damage to the hair. Gentle brushing with a soft brush should replace more aggressive brushing, ratting, or other procedures. Harsh chemicals such as hair straightening compounds and permanents should be avoided. The hair should not be ironed. Excessively harsh shampoo should be avoided. Hair conditioners should be used.
Isolated hypogonadotropic hypogonadism (IHH), also called idiopathic or congenital hypogonadotropic hypogonadism (CHH), as well as isolated or congenital gonadotropin-releasing hormone deficiency (IGD), is a condition which results in a small subset of cases of hypogonadotropic hypogonadism (HH) due to deficiency in or insensitivity to gonadotropin-releasing hormone (GnRH) where the function and anatomy of the anterior pituitary is otherwise normal and secondary causes of HH are not present. Presentation
Congenital hypogonadotropic hypogonadism presents as hypogonadism, e.g., reduced or absent puberty, low libido, infertility, etc. due to an impaired release of the gonadotropins, follicle-stimulating hormone (FSH) and luteinizing hormone (LH), and a resultant lack of sex steroid and peptides production by the gonads.In Kallmann syndrome, a variable non-reproductive phenotype occurs with anosmia (loss of the sense of smell) including sensorineural deafness, coloboma, bimanual synkinesis, craniofacial abnormalities, and/or renal agenesis. Causes
IHH is divided into two syndromes: IHH with olfactory alterations or anosmia, Kallmann syndrome  and IHH with normal smell (normosmic IHH).Kallmann syndrome is responsible for approximately 50% of all cases of the condition. It is associated with mutations in KAL1, FGFR1/FGF8, FGF17, IL17RD, PROKR2, NELF, CHD7(which positively regulates GnRH secretion), HS6ST1, FLRT3, SPRY4, DUSP6, SEMA3A, and WDR11 (gene), genes which are related to defects in neuronal migration.Gene defects associated with IHH and normal smell include PROKR2, FGFR1, FGF8, CHD7, DUSP6, and WDR11, as in KS, but in addition
also mutations in KISS1R, TACR3, GNRH1/GNRHR, LEP/LEPR, HESX1, FSHB, and LHB.