MedGen

Familial partial lipodystrophy is a metabolic disorder characterized by abnormal subcutaneous adipose tissue distribution beginning in late childhood or early adult life. Affected individuals gradually lose fat from the upper and lower extremities and the gluteal and truncal regions, resulting in a muscular appearance with prominent superficial veins. In some patients, adipose tissue accumulates on the face and neck, causing a double chin, fat neck, or cushingoid appearance. Metabolic abnormalities include insulin-resistant diabetes mellitus with acanthosis nigricans and hypertriglyceridemia; hirsutism and menstrual abnormalities occur infrequently. Familial partial lipodystrophy may also be referred to as lipoatrophic diabetes mellitus, but the essential feature is loss of subcutaneous fat (review by Garg, 2004). The disorder may be misdiagnosed as Cushing disease (see 219080) (Kobberling and Dunnigan, 1986; Garg, 2004). Genetic Heterogeneity of Familial Partial Lipodystrophy Familial partial lipodystrophy is a clinically and genetically heterogeneous disorder. Types 1 and 2 were originally described as clinical subtypes: type 1 (FPLD1; 608600), characterized by loss of subcutaneous fat confined to the limbs (Kobberling et al., 1975), and FPLD2, characterized by loss of subcutaneous fat from the limbs and trunk (Dunnigan et al., 1974; Kobberling and Dunnigan, 1986). No genetic basis for FPLD1 has yet been delineated. FPLD3 (604367) is caused by mutation in the PPARG gene (601487) on chromosome 3p25; FPLD4 (613877) is caused by mutation in the PLIN1 gene (170290) on chromosome 15q26; FPLD5 (615238) is caused by mutation in the CIDEC gene (612120) on chromosome 3p25; FPLD6 (615980) is caused by mutation in the LIPE gene (151750) on chromosome 19q13; FPLD7 (606721) is caused by mutation in the CAV1 gene (601047) on chromosome 7q31; FPLD8 (620679), caused by mutation in the ADRA2A gene (104210) on chromosome 10q25; and FPLD9 (620683), caused by mutation in the PLAAT3 gene (613867) on chromosome 11q12. [from OMIM]

Abacavir is a nucleoside reverse transcriptase inhibitor indicated for the treatment of HIV infection, in combination with other medications, as part of highly active antiretroviral therapy. Although abacavir is generally well tolerated, ~5–8% of patients experience a hypersensitivity reaction (HSR) during the first 6 weeks of treatment. Suspicion of an HSR requires immediate discontinuation of abacavir. Drug re-challenge is contraindicated because immediate life-threatening reactions can occur. HLA-B is a member of the major histocompatibility complex gene family and patients with at least one HLA-B*57:01 allele may develop HSR when treated with abacavir. HLA-B allele status has no effect on abacavir pharmacodynamics or pharmacokinetics; it only influences the likelihood that an HSR will occur. Guidelines regarding the use of pharmacogenomic tests in dosing for abacavir have been published in Clinical Pharmacology and Therapeutics by the Clinical Pharmacogenetics Implementation Consortium (CPIC) and are available on the PharmGKB website. [from PharmGKB]

Efavirenz is a non-nucleoside reverse transcriptase inhibitor widely used worldwide to treat HIV-1 infection. It is predominantly metabolized into inactive metabolites by cytochrome P450-2B6 (CYP2B6). Genetic variants in CYP2B6 (e.g. CYP2B6*6 and *18), along with other genetic and non-genetic factors, are known to influence variability in efavirenz response. Patients with certain CYP2B6 genetic polymorphisms may be at increased risk for adverse effects, particularly central nervous system toxicity and treatment discontinuation. [from PharmGKB]

NCFTD is an autosomal recessive disorder resulting from brain-specific folate deficiency early in life. Onset is apparent in late infancy with severe developmental regression, movement disturbances, epilepsy, and leukodystrophy. Recognition and diagnosis of this disorder is critical because folinic acid therapy can reverse the clinical symptoms and improve brain abnormalities and function (Steinfeld et al., 2009). [from OMIM]

SADDAN dysplasia (severe achondroplasia with developmental delay and acanthosis nigricans) is a very rare skeletal dysplasia characterized by the constellation of these features. Radiology reveals 'ram's horn' shaped clavicles and reverse bowing of lower limbs. Approximately half of patients die before the fourth week of life secondary to respiratory failure (summary by Zankl et al., 2008). [from OMIM]

Abnormal thyroid hormone metabolism-2 (THMA2) is characterized by elevated serum reverse triiodothyronine (rT3) levels and rT3/T3 ratios. Some patients exhibit resistance to thyroid-stimulating hormone (TSH; see 188540) with mildly elevated TSH levels, and elevated cholesterol levels have been observed (Franca et al., 2021). For a discussion of genetic heterogeneity of abnormal thyroid hormone metabolism, see THMA1 (609698). [from OMIM]

A rare developmental anomaly, affecting primarily the anterior part of the maxilla and nasal complex. Affected individuals typically have an unusually flat, underdeveloped midface, with an abnormally short nose and flat nasal bridge, underdeveloped upper jaw, relatively protruding lower jaw and/or a ''reverse overbite'' (or class III malocclusion). Hypoplasia of distal phalanges of fingers was reported in some cases. The pathogenesis remains uncertain, most reported cases were sporadic. [from SNOMEDCT_US]

Breathing movements in which the chest wall moves in on inspiration and out on expiration, in reverse of the normal movements. It may be seen in children with respiratory distress of any cause, which leads to indrawing of the intercostal spaces during inspiration. Patients with chronic airways obstruction also show indrawing of the lower ribs during inspiration, due to the distorted action of a depressed and flattened diaphragm. Crush injuries of the chest, with fractured ribs and sternum, can lead to a severe degree of paradoxical breathing. [from HPO]

Abnormal thyroid hormone metabolism-3 (THMA3) is characterized by euthyroid hyperthyroxinemia, with elevated free T4 and reverse T3 levels, and normal TSH (see 188540) and free T3 levels. Patients also show low plasma selenium levels and reduced levels of stress-related selenoproteins (Schoenmakers et al., 2016; Geslot et al., 2021). For a discussion of genetic heterogeneity of abnormal thyroid hormone metabolism, see THMA1 (609698). [from OMIM]

Abnormal thyroid function tests, low triiodothyronine with elevated reverse triiodothyronine, in the setting of non-thyroidal illness. [from NCI]

A rare, congenital anomaly of the great arteries characterized by cranially situated aortic arch ascending into the neck above the clavicles. Most patients remain asymptomatic, some present with a murmur and a pulsatile neck mass, stridor, dyspnea, recurrent bronchitis, dysphagia or signs and symptoms of a stenosis/aneurism of the aortic arch. Other congenital heart anomalies are frequently associated, including abnormalities of arch laterality and branching, aortic coarctation or aneurysm. [from ORDO]