Relatives of patients

Studies conducted in twins show a threefold increased risk of psoriasis in monozygotic twins versus fraternal twins.7 In addition, based on a study in 3,095 families with psoriasis, the calculated lifetime risk of developing psoriasis if no parent, one parent, or both parents have psoriasis was found to be 0.04, 0.28, and 0.65, respectively. If there was already one affected child in the family, the risks were increased to 0.24, 0.51, and 0.83, respectively.7,9 As many as 71% of patients with psoriasis during childhood have some positive family history.1 Similarly, psoriatic arthritis is heritable, with a prevalence 19 times higher in first-degree relatives of patients with psoriatic arthritis than in the general population.7... 

Up to 25% of patients who develop colorectal cancer will have a family history of colorectal cancer unrelated to one of the mutations just described. First-degree relatives of patients diagnosed with colorectal cancer have an increased risk of the disease that is at least two to four times that of persons in the general population without a family history.15... 

Mayeux, R., Sano, M., Chen, J., Tatemichi, T. and Stern, Y. Risk of dementia in first-degree relatives of patients with Alzheimer s disease and related disorders. Arch. Neurol. 48 269-273, 1991. 

Ventilatory abnormalities have been identified in first-degree relatives of patients with panic disorder (Perna et ah, 1995 Coryell, 1997), as well as in patients with possible precursors for panic disorders, such as separation anxiety disorder (Pine et ah, 2000) or isolated panic attacks (Perna et ah, 1995). Additionally, studies have found family loading for panic disorder in the relatives of panic patients with respiratory abnormalities (Perna et al., 1996), suggesting that hypersensitivity to CO2 inhalation may be a trait marker for panic disorder rather than a state marker. These data suggest that parents with panic disorder may transmit a diathesis for certain forms of anxiety (e.g., separation anxiety disorder) that is observable in the respiratory... 

Nicoison, R., Hommer, D., Thaker, G., Brown, M., Bedwell, M., Lenane, M., Fernandez, T, and Rapoport, J.L. (1999b) Smooth pursuit eye movements in the relatives of patients with childhood-onset schizophrenia. Schizophr Res 36 93. 

Rieder RO, Mann LS, Weinberger DR, et al. Computed tomographic scans in patients with schizophrenia, schizoaffective, and bipolar affective disorder. Arch Gen Psychiatry 1983 40 735-739. Tsuang MT, Winokur G, Crowe RR. Morbidity risks of schizophrenia and affective disorders among first degree relatives of patients with schizophrenia, mania, depression, and surgical conditions. Br J Psychiatry 1980 137 497-504. 

Several large studies have investigated the prevalence of both Tourette s disorder and OCD in index cases having Tourette s disease ( 161, 162). In the cases of Tourette s disorder with OCD symptoms, the age-corrected ratio is 18%, with relatives having Tourette s disorder, chronic tics, or OCD (10%). in relatives of patients that have Tourette s symptoms only, 17% have either Tourette s disorder or chronic tic disorder and 14% have OCD. Thus, the incidence of OCD in relatives is identical in index cases of those with Tourette s disorder with OCD and index cases of Tourette s disorder only. Finally, follow-up studies find that Tourette s disorder develops in a significant percentage of children with OCD (163). 

Comings DE, Comings BG. Hereditary agoraphobia and obsessive-compulsive behavior in relatives of patients with Giles de la Tourette s syndrome. Br J Psychiatry 1987 15 195-199. 

Lenane M, Swedo SE, Rapoport JL. Rates of obsessive compulsive disorder for first-degree relatives of patients with trichotillomania. J Child Psychol Psychiatry 1992 33 925-933. 

Life Events and the Two-Hit Hypothesis of Psychiatric Disorders. One theory that tries to explain this combination of genetic vulnerabilities and environmental factors as the basis of many psychiatric disorders is the two-hit hypothesis. That is, in order to manifest an overt psychiatric disorder, one must not only sustain the first hit, namely all the critical genetic vulnerabilities, but one must also sustain a second hit of some type from the environment (Figs. 4-2 through 4-5). Thus, psychiatric disorders are increased in incidence in first-degree relatives of patients with a wide variety of psychiatric disorders but not to an extent that allows one to predict which specific individuals will or will not eventually develop a specific psychiatric disorder. 

Panic disorder affects up to 2% of the population, but less than one-third receive treatment. Panic disorder typically begins in late adolescence or early adulthood but can present in childhood. Onset is rare after age 45. Panic disorder is more prevalent in women, who have perhaps twice the rate in men. Genetic studies demonstrate a 15 to 20% rate of panic disorder in relatives of patients with panic disorder, including a 40% concordance rate for panic disorder in monozygotic twins. 

The administration of 131I requires safety measurements to reduce to a minimum the irradiation of medical personnel and to avoid contamination of rooms and relatives of patients. Capsules containing 131I are therefore to be preferred to liquid iodine. At doses above 25 mCi (555 MBq), usually intended only for treatment of patients with thyroid cancer, isolation in a specially constructed room of a service for nuclear medicine is necessary. Waste disposal should also be carefully managed so as to avoid overall contamination (5,6). 

Boos HB, Aleman A, Cahn W, Pol HH, Kahn RS. 2007. Brain volumes in relatives of patients with schizophrenia A meta-analysis. Arch Gen Psychiatry 64 297-304. 

Seidman LJ, Faraone SV, Goldstein JM, Goodman JM, Kremen WS, et al. 1999. Thalamic and amygdala-hippocampal volume reductions in first-degree relatives of patients with schizophrenia An MRI-based morphometric analysis. Biol Psychiatry 46 941-954. 

A growing number of studies have begun to examine whether early visual processing deficits are endophenotypes of schizophrenia (See DeLisi this volume). Endophenotypes are biological markers of the disease are familial (e.g., are seen in first degree relatives of patients with schizophrenia) and can be used as phenotypes in genetic analyses. 

Cerebral phosphate metabolism in first-degree relatives of patients with schizophrenia. Am J Psychiatry 158 958-960. 

Jessen F, Fries T, Kucharski C, Nishimura T, Hoenig K, Maier W, Falkai P, Heun R. 2001. Amplitude reduction of the mismatch negativity in first-degree relatives of patients with schizophrenia. Neurosci Lett. 309 185-188. 

Raaymakers TW (1999). Aneurysms in relatives of patients with subarachnoid hemorrhage frequency and risk factors. MARS Study Group. Magnetic Resonance Angiography in Relatives of patients with subarachnoid hemorrhage. Neurology 53 982-988... 

A number of studies have reported low semm concentrations of retinol and high concentrations of /3-carotene in patients with insulin-dependent diabetes mellitus. Krill and coworkers (1997) showed that up to one-third of nondiabetic first-degree relatives of patients with diabetes also showed a low serum retinokcarotene ratio, implying a genetic predisposition to low activity of carotene dioxygenase, possibly associated with insulin-dependent diabetes. 

Cross S, Kim SJ, Weiss LA, Delahanty RJ, Sutcliffe JS, Leventhal BL, Cook EH Jr, Veenstia-Vanderweele J (2008) Molecular genetics of the platelet serotonin system in first-degree relatives of patients with autism. Neuropsychopharmacology 33 353—360... 

Klaasen T, Riedal WJ, van Someren A, Deutz NE, Honig A, van Praag HM. Mood effects of 24-hour tryptophan depletion in healthy first-degree relatives of patients with affective disorders. Biol. Psychiatry 1999 46 489-497. 

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