Clinical Profile and Molecular Genetic Analysis of Prader - Willi Syndrome: A Single Center Experience

The prevalence of childhood and adolescent obesity is increasing worldwide as well as in India. Prader--Willi syndrome (PWS) is one of the most common causes of syndromic obesity with varied clinical manifestations across different lifespan. Herewith, we describe clinical and molecular characteristics of eight PWS who were diagnosed in an obesity clinic of tertiary care hospital.

Clinically suspected cases of PWS were screened between January 2014 and January 2022. Detailed history and clinical examination were done to look for typical features of PWS like characteristic facial appearance, short stature, obesity, hyperphagia, delayed puberty or hypogonadism, diabetes mellitus, developmental delay, cognitive dysfunction, learning disabilities or abnormal behavior. All were evaluated, with 75 g oral glucose tolerance tests (GTT), HbA1c, Free T4, TSH, LH, FSH, testosterone, and growth hormone level. Intelligent quotient (IQ) of each patient was assessed by a psychiatrist using Binet-Kamat test. Molecular confirmation of clinically suspected PWS was done by either Methylation-specific polymerase chain reaction (MS-PCR) or Fluorescence in situ Hybridization (FISH) methods.

Based on clinical and molecular characteristics, eight were diagnosed as PWS. Except one, all were male with characteristic facies, mean age of study cohort was 12 years and mean BMI of 44.58. Obesity, short stature, hyperphagia, hypotonia, and mild to moderate mental retardation were noted in entire (100%) PWS study population. All male PWS patients had cryptorchidism, which was bilateral in six patients and unilateral (right undescended testes) in one. Apart from obesity, short stature, other endocrine associations noted were diabetes mellitus in 50% and subclinical hypothyroidism in 37% of PWS. Molecular characteristics of PWS were confirmed by Methylation-specific PCR in seven and by FISH method in one.

Prader-Willi syndrome should be kept in mind in case of childhood or adolescent obesity with short stature, hypotonia, cryptorchidism, and developmental delay or cognitive dysfunction. Judicious use of molecular diagnostic testing should be made in all clinically suspected cases. Early diagnosis and appropriate management of this complex disorder by a multidisciplinary team will improve the quality of life and treatment outcome.