Alström syndrome is characterized by cone-rod dystrophy, obesity, progressive bilateral sensorineural hearing impairment, acute infantile-onset cardiomyopathy and/or adolescent- or adult-onset restrictive cardiomyopathy, insulin resistance / type 2 diabetes mellitus (T2DM), nonalcoholic fatty liver disease (NAFLD), and chronic progressive kidney disease. Cone-rod dystrophy presents as progressive visual impairment, photophobia, and nystagmus usually starting between birth and age 15 months. Many individuals lose all perception of light by the end of the second decade, but a minority retain the ability to read large print into the third decade. Children usually have normal birth weight but develop truncal obesity during their first year. Sensorineural hearing loss presents in the first decade in as many as 70% of individuals and may progress to the severe or moderately severe range (40-70 db) by the end of the first to second decade. Insulin resistance is typically accompanied by the skin changes of acanthosis nigricans, and proceeds to T2DM in the majority by the third decade. Nearly all demonstrate hypertriglyceridemia. Other findings can include endocrine abnormalities (hypothyroidism, hypogonadotropic hypogonadism in males, and hyperandrogenism in females), urologic dysfunction / detrusor instability, progressive decrease in renal function, and hepatic disease (ranging from elevated transaminases to steatohepatitis/NAFLD). Approximately 20% of affected individuals have delay in early developmental milestones, most commonly in gross and fine motor skills. About 30% have a learning disability. Cognitive impairment (IQ <70) is very rare. Wide clinical variability is observed among affected individuals, even within the same family.

INSR-related severe syndromic insulin resistance comprises a phenotypic spectrum that is a continuum from the severe phenotype Donohue syndrome (DS) (also known as leprechaunism) to the milder phenotype Rabson-Mendenhall syndrome (RMS). DS at the severe end of the spectrum is characterized by severe insulin resistance (hyperinsulinemia with associated fasting hypoglycemia and postprandial hyperglycemia), severe prenatal growth restriction and postnatal growth failure, hypotonia and developmental delay, characteristic facies, and organomegaly involving heart, kidneys, liver, spleen, and ovaries. Death usually occurs before age one year. RMS at the milder end of the spectrum is characterized by severe insulin resistance that, although not as severe as that of DS, is nonetheless accompanied by fluctuations in blood glucose levels, diabetic ketoacidosis, and – in the second decade – microvascular complications. Findings can range from severe growth delay and intellectual disability to normal growth and development. Facial features can be milder than those of DS. Complications of longstanding hyperglycemia are the most common cause of death. While death usually occurs in the second decade, some affected individuals live longer.

Bangstad syndrome is a rare endocrine disease characterized by the association of primordial birdheaded nanism, progressive ataxia, goiter, primary gonadal insufficiency and insulin resistant diabetes mellitus. Plasma concentrations of TSH, PTH, LH, FSH, ACTH, glucagon, and insulin are usually elevated. A generalized cell membrane defect was suggested to be the pathophysiological abnormality in these patients. The mode of inheritance was thought to be autosomal recessive. There have been no further descriptions in the literature since 1989.

Wolcott-Rallison syndrome is a rare autosomal recessive disorder characterized by permanent neonatal or early infancy insulin-dependent diabetes. Epiphyseal dysplasia, osteoporosis, and growth retardation develop at a later age. Other frequent multisystem manifestations include hepatic and renal dysfunction, mental retardation, and cardiovascular abnormalities (summary by Delepine et al., 2000).

SHORT syndrome is a mnemonic for short stature, hyperextensibility, ocular depression (deeply set eyes), Rieger anomaly, and teething delay. It is now recognized that the features most consistently observed in SHORT syndrome are mild intrauterine growth restriction (IUGR); mild to moderate short stature; partial lipodystrophy (evident in the face, and later in the chest and upper extremities, often sparing the buttocks and legs); and a characteristic facial gestalt. Insulin resistance may be evident in mid-childhood or adolescence, although diabetes mellitus typically does not develop until early adulthood. Other frequent features include Axenfeld-Rieger anomaly or related ocular anterior chamber dysgenesis, delayed dentition and other dental issues, and sensorineural hearing loss.

Familial partial lipodystrophy type 1 (FPLD1), or Kobberling-type lipodystrophy, is characterized by loss of adipose tissue confined to the extremities, with normal or increased distribution of fat on the face, neck, and trunk (Kobberling and Dunnigan, 1986). For a general description and a discussion of genetic heterogeneity of familial partial lipodystrophy (FPLD), see 151660.

Familial partial lipodystrophy (FPLD) 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.

A rare familial partial lipodystrophy with characteristics of adult onset of distal lipoatrophy with gluteofemoral fat loss, as well as increased fat accumulation in the face and trunk and visceral adiposity. Additional manifestations include diabetes mellitus, atherogenic dyslipidemia, eyelid xanthelasma, arterial hypertension, cardiovascular disease, hepatic steatosis, acanthosis nigricans on axilla and neck, hirsutism, and muscular hypertrophy of the lower limbs. Caused by heterozygous mutation in the PPARG gene on chromosome 3p25.

Mandibuloacral dysplasia with type B lipodystrophy (MADB) is a rare autosomal recessive disorder characterized by postnatal growth retardation, craniofacial anomalies such as mandibular hypoplasia, skeletal anomalies such as progressive osteolysis of the terminal phalanges and clavicles, and skin changes such as mottled hyperpigmentation and atrophy. The lipodystrophy is characterized by generalized loss of subcutaneous fat involving the face, trunk, and extremities. Some patients have a progeroid appearance. Metabolic complications associated with insulin resistance have been reported (Schrander-Stumpel et al., 1992; summary by Simha et al., 2003). For a general phenotypic description of lipodystrophy associated with mandibuloacral dysplasia, see MADA (248370).

A rare syndromic retinitis pigmentosa characterized by pigmentary retinopathy, diabetes mellitus with hyperinsulinism, acanthosis nigricans, secondary cataracts, neurogenic deafness, short stature mild hypogonadism in males and polycystic ovaries with oligomenorrhea in females. Inheritance is thought to be autosomal recessive. It can be distinguished from Alstrom syndrome (see this term) by the presence of intellectual disability and the absence of renal insufficiency. There have been no further descriptions in the literature since 1993.

Familial partial lipodystrophy type 4 is an autosomal dominant metabolic disorder characterized by childhood or young adult onset of loss of subcutaneous adipose tissue primarily affecting the lower limbs, insulin-resistant diabetes mellitus, hypertriglyceridemia, and hypertension (summary by Gandotra et al., 2011). Other features may include hepatic steatosis, acanthosis nigricans, polycystic ovary syndrome, and renal disease (summary by Chen et al., 2018). For a general phenotypic description and a discussion of genetic heterogeneity of familial partial lipodystrophy (FPLD), see 151660.

Mandibuloacral dysplasia with type A lipodystrophy (MADA) is an autosomal recessive disorder characterized by growth retardation, craniofacial anomalies with mandibular hypoplasia, skeletal abnormalities with progressive osteolysis of the distal phalanges and clavicles, and pigmentary skin changes. The lipodystrophy is characterized by a marked acral loss of fatty tissue with normal or increased fatty tissue in the neck and trunk. Some patients may show progeroid features. Metabolic complications can arise due to insulin resistance and diabetes (Young et al., 1971; Simha and Garg, 2002; summary by Garavelli et al., 2009). See also MAD type B (MADB; 608612), which is caused by mutation in the ZMPSTE24 gene (606480).

Familial partial lipodystrophy type 9 (FPLD9) is an autosomal recessive metabolic disorder characterized by the loss of adipose tissue resulting in a lean appearance with muscular hypertrophy, usually most apparent in the limbs and trunk. Some patients have more generalized lipoatrophy, whereas others have abnormal fat accumulation in the face and neck regions and show cushingoid or acromegalic facial features. The disorder is associated with insulin-resistant diabetes mellitus, dyslipidemia, low HDL, and hepatic steatosis. Symptom onset is usually in the first decade. Females tend to have hirsutism and polycystic ovary syndrome, whereas males have gynecomastia. Most patients also have neurologic involvement, including demyelinating polyneuropathy (in most) and delayed development with intellectual disability (in about half) (Schuermans et al., 2023). For a discussion of genetic heterogeneity of familial partial lipodystrophy (FPLD), see 151660.